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Welcome to the Electric Car Weblog. In addition to links, news, and tips about electric cars and other forms of alternative transportation we are publishing an on-line diary of our current EV project. Started in August 2005 the chronicle follows the conversion of a gas powered Ford Probe into an Electric Car.

You will find articles organized by categories, along with recent comments, along the right hand column of the website. If you are just getting started with the idea of converting a gas car to electric be sure to check out Your First Electric Car

Welcome and enjoy!

The Battery Dilemma · 10 April 06

Optima Yellowtop

Now that the weather has started warming up and my other projects are winding down I’ve cracked open the garage door and started measuring Eve for her spring wardrobe.

I know, I’ve been putting it off: stalling, dawdling, jerrymeandering, going to the thesaurus to look up alternatives to procrastination just so I don’t have to actually think about them.


Batteries. Love ‘em or hate ‘em, ya gotta have batteries in an electric car.

At some point you have to make a decision so that metal can be cut, frames welded, boxes built, and wiring run in preparation for the big day when you heft a dozen batteries into the EV.

I made a vow that I’d try something besides the basic lead-acid for this conversion. AGM, NiCAD, Gel, NiMh, Lithium…something. I’d like something that, a) doesn’t need to be watered, and b) lasts longer. Things like high surge power, ability to mount on its side are bonus points.

The main problem is sticker shock. That and finding out if the damn things can even be purchased. Seriously. Company A comes out with a series of press releases for their newer, better, cheaper, safer, more powerful battery. Nobody has them for sale. Inquiries to the company either go unanswered or are met with a meaningless form letter, “Thank you for your interest. You don’t seem to be a big company…good bye.

So we work with what we have, it takes enough time to figure out existing products, no reason to waste days trying to chase down ghosts of future tech.

What do we need from a battery? Here’s what I know:

  • Voltage – well, duh! Seriously, the higher the voltage your overall system (higher volts typically mean better performance) the more batteries you will need. If you also want range then you’ll want big batteries, i.e. 6 volt deep cycle, which means even MORE batteries. Eve will run at 144vdc: either twelve 12v, eighteen 8v, or twenty-four 6v batteries.
  • Current – even if you’ve never bought a battery for your car you’ve probably seen the ads on TV: MORE COLD CRANKING AMPS! Meaningless. The battery in your car has to turn a small electric motor (starter) a few times a day, sometimes when things are cold and creaky but there’s no way the battery can pull those kinds of amps for more than a minute or two. Our electric car batteries need to pull 300 to 500 amps from time to time and around a hundred amps most of the time. Doc
  • Amp Hours – think of this as a measure of work a battery can do. Like gallons of gas, amp hours gives an approximation of how long you can run at a specific current draw before dropping to 10.5 volts (considered “empty” for a 12v battery). Amp hours, like anti-depressants, come with all kinds of fine print and caveats: actual amp hours can be negatively effected by temperature, rate of discharge, jostling, bad thoughts, past charging or lack thereof, sudden elevation swings, and unfair atmospheric pressure. Do not taunt the amp hours, keep away from children and adults, do not expose to sunlight, keep out of darkness, store in a cool dry place, your mileage may vary…
  • Cycle Life – while amp hours try to quantify how much work you can squeeze out of a battery the cycle life is how long you should expect them to put up with this abuse. Typically with lead acid deep cycle batteries it is stated as the number of times you can drain 80% out of the battery. I’ve noticed that most of the AGMs express this as 50% cycles and really don’t suggest going down to 80%, so buyer beware. What may not be obvious is that you can get more cycles by not draining as deeply but far fewer if you regularly over-drain and/or abuse the batteries. Which says to me: get more than you need.
  • Cost – it’s more complicated than finding the cheapest. There’s typically a reason why one battery is cheaper than another. Yes, you can buy a starter battery pretty cheap at *Mart but it’s not even close to the performance of a deep cycle battery. All deep cycle batteries are not created equal either.

That’s a bunch of things to evaluate and it’s only the tip of the iceberg. Do you drive in cold weather? Knock 30% off the expected capacity. Do you drive like a grandma?1 Bump up the life cycles. Do you live in steep, hilly country? You’ll want more current and capacity. Are you a racer? Get out the checkbook…
1 an unfair generalization: Grandma Halstead drove faster and crazier than most folks I know

The best tools in your search for an electric car battery is a spreadsheet and lots of information to dump into it.

Math stuff

Years ago I created reports from databases that a VP would use at company meetings. I noticed a particular trend, which I’ve seen at other companies, with other VPs and Presidents: creative rounding.

Whenever things were dire and they were trying to boost moral they’d creatively round UP the numbers. Instead of saying that sales were $170,000 they might say “nearly a quarter million.” The same number in a sales meeting, meant to get them off their butts and selling, might round DOWN to become “barely cracked a hundred thousand, what’s up with you people?”

We do the same thing. I tell my wife that something’s only ninety bucks, while she points out that $99.99 is really a hundred bucks hiding under a penny.

You don’t want to to too much creative rounding when choosing batteries. This isn’t horse shoes or hand grenades, if you short change your EV with cheap batteries it will catch up with you eventually. Remember, there isn’t any free energy. On the other hand the consensus of the EVList is that most folks kill their first battery pack; maybe buying a cheaper first pack has some merit? Math is easy Barbie

Enough yacking, let’s do some battery math.

I’ve gathered formulas from a number of places and added a few of my own to build up my what-if spreadsheet. Feel free to correct me if you think I’ve strayed too far.

range = energy in pack / energy used per mile
energy in pack = 20 ah rating * .57 * voltage
energy used per mile = 160 W-hr

It’s not perfect, but it’s a formula that we can use with all of the batteries. Ideally we would love to have the 1hr rate for all batteries, but battery specs are frustratingly inconsistent and typically the best we can get for all of them is the 20hr rate. The 0.57 is a number that folks use to approximate the 1hr rate given a 20hr rate.

Also you need to draw a line in the sand and decide on a rate of consumption for the formulas. In this case the 160 watt hours per mile is what the EV Calculator shows for driving 35mph with my setup and a 1% incline. Note, the range calculation is based on power only and doesn’t take into account the weight of the battery packs, incline, or other outside factors.

cost per mile = battery cost / miles in pack
miles in pack = range * cycle life
battery cost = # batteries * price

miles per lb = range / battery pack weight
battery pack weight = # batteries * battery weight

Cycle Life Chart

Toughest thing in this bunch, and vital to some of the more interesting calculations is the cycle life. There’s a few battery charts with this information, some anecdotal evidence from EV’ers, but this is an elusive number to find. 6volt deep cycle batteries are in the neighborhood of 700 cycles. 12volt batteries from the same companies are typically half of that, mostly because there’s less plate material and lighter construction. AGMs are generally in the 300 cycle range, some less, some more, and some claiming numbers that nobody has had a chance to prove yet.

Remember that AGMs (and some other advanced batts) report the cycles for 50% DOD (depth of discharge) while the heavy old lead acids are 80% DOD ratings. One rule of thumb is that only discharging 50% for those 80% rated batteries increases their cycle life 50%. So a 300 cycle lead acid Trojan could clock in at 450 cycles if you treat them well…but that also means less range.

In order to compare apple to apples we probably should use the same DOD and bump up the cycles for the 80% DOD batteries by 50%. I’ve done this as best as I can in the spreadsheet below.

A few more numbers that I think are interesting.

cost per year = battery cost / years
years = miles in pack / estimated yearly miles
ten year cost = cost per year * 10 + ($300 * (10/years - 1))

The last one is something I just made up. Let’s figure that most of us will try to keep the EV running for ten years. If we had a battery pack that lasted ten years then it’s just a matter of popping them in and enjoying the next ten years. On the other hand if we bought the cheapest batteries imaginable and they only lasted a year we’d be replacing them ten times over that period (assuming we didn’t smarten up). Since time is money, even for zealots, I’m factoring in a $300 time and trouble tax for each time the pack gets changed. Seems reasonable.

Ready? Here’s the pile-o-numbers!

Battery comparison spreadsheet

Click to see a more readable version, you can download the spreadsheet here. Lot’s of caveats here…LOTS, and I suspect that I’ll have to redo this a number of times so check back from time to time. Also, I’ll try to make the base spreadsheet available to anyone who is interested, drop me an email.

The main caveat is the dang cycle numbers. Jeesh, those are as hard to find as unicorns or decent politicians (which one is imaginary is left as an exercise to the reader) and a chart like this doesn’t help. The next near-fable is the price. You’ll find a battery for, say, $100 on one website and then the same battery for almost $300 on another! Which one is the scam? Be sure to contact me if you have updated numbers for any of these.

I didn’t shop around much when I bought batteries for the first EV. After a couple of days poking around this time I’ve found that the prices are highly variable. Mention that you are going to buy a dozen batteries and the special pricing comes out. I hope that this holds true with all of the battery sellers.

Now that we’ve run some numbers, what have we learned? Well, no surprise that the cheapest approach in the long run is still with the stalwart lead-acid deep cycle batteries from Trojan and US Battery. The chart is showing estimate life expectancies of over ten years for the six volt packs…that’s assuming I don’t do something stupid like forget to water them, have a charger go bad and cook them (it’s happened), or get a bad batch. All of which could happen to the other batteries.

If you glance over at total weight column you’ll see the downside: fifteen to eighteen hundred pounds of batteries! Mon dieu, celui est beaucoup de pile! (I’m taking a french class with my wife)

Yeah, forget that. Maybe if I was converting a small pickup.

Trojan J150

If I were to stick with basic lead-acid I think the Trojan J150 is the way to go. It has the same internal design (plate size, etc..) as the T-105 but in a 12v package. A thousand pounds for a twelve pack of them, that’s a couple hundred pounds heavier than the SCS225’s I used to use, but over four hundred pounds lighter than the T-105s. They are taller by a little over an inch but my old battery boxes were constructed to handle taller batteries

The main feature of the J150 is the longer cycle life, always the achilles heal of most 12v deep cycle batteries. With an 80% DOD cycle life around 700 vs 300 the initial extra expense pays off over the long run with J150’s costing $1,200 less over ten years.

Still, I’d rather not go with flooded lead-acid if I don’t have to. I don’t need much range: daily driving around 10 miles, 20 on long range days. Also, except for climbing the hills to our house, I don’t need high performance, although it would be nice to have a little pep when showing the car off.

Horizon Picher

An interesting battery is the EaglePicher Horizon 12D2000. It’s an AGM with a unique form factor, as you can see: 30” x 4” x 5”. No need for watering, which means they can be put in inaccessible locations like the groove down the middle of the car where the muffler pipe used to run and the indent formerly occupied by the gas tank. They can’t lay on their side, but upside down is OK.

You pay extra for all of that convenience. The manufacturer suggested price of $329 (I haven’t looked for a dealer or quantity pricing yet) makes the initial cost more than double that for the J150’s. Yet it has a high cycle life of 1200 @ 50% DOD and a good ah rating (I converted the C/3 rate to C/20). Another thing going for it is a pack weight 100lbs lighter than my last pack and if you use the “jerry-factor” it comes to the same relative cost over a period of ten years (less if I get a quantity discount).

Dynasty DCS-100L

Next candidate is the Dynasty DCS-100L. The DCS-100L is also an AGM and has a more traditional battery form factor. When I first started researching batteries I ran across a cycle life for this battery of 600 cycles, but I can’t seem to find that spelled out in any of the company’s current literature.

There’s an EVList post from 2002 that lists the 50% rating as 1200, which is the kind of thing we like to hear. Form factor-wise they are close to the SCS225 size, an inch less in length, with about the same weight. Not much else to say, maybe I can find some EV’ers with first hand experience?

Deka MK Gel

I’m not as familiar with the Deka MK 8G31 Gel cell batteries (PDF here). Gels claim a higher cycle life than AGMs. From what I’ve read they aren’t able to supply as high of an on-demand current, like what an EV racer would want.

I’ve downloaded their PDF on VRLA Gel and AGM batteries, for some late night reading.

Thundersky Lithium

Which brings us to Lithium (forget NiMH, I think Chevron has pretty much killed/monopolized this choice). Thundersky out of China is the lithium of choice for EVs it seems, at least that’s the one I’ve heard the most about. I exchanged email with them last fall and got the prices shown in the spreadsheet (600+ bulk purchase, add $5/ea to the smaller batts for smaller orders).

The most attractive thing with Lithium is the energy density and cycles. In a 210lb package of batteries I can get all the range I need and they’ll last for well over ten years. Heck, Eve would weight in at under 3,000lbs. They’re the only batteries that cost less to run for ten years than it does to purchase them (which speaks more to my spreadsheet skills than reality!)/ ’:^)

The downside is that it’s going to cost big bucks for that luxury. Not as much as Valence or Kokam, but almost $6,000 just to outfit the car with a lithium battery pack. I’d be in good company though.

That’s where I’m at with batteries: a spreadsheet full of numbers, browser full of bookmarks, and a folder packed full of brochures and specs.

The easiest thing to do would be to go with lead-acid: cheap, I’m familiar with them, and no need for a battery management system. I’m really resisting the urge to take the path of least resistance. My inclination is to see what kind of quantity price I can get and go with the Horizon AGMs. There’s a certain attraction to being able to put the batteries wherever I want, optimize the center of gravity, and hopefully get ten years or so out of the pack.

Of course I’m always open to the possibility of a battery manufacturer or distributor sending a pack this way in exchange for site advertising! Oh, and, a, technical evaluation…

Update: As Ryan notes, I’d forgotten to mention the additional cost of a BMS. You HAVE to have one for lithiums and it’s probably a really good idea to have one for the AGM/Gel batteries as well. From reading Lee’s posts about his BMS it sounds like everyone, lead-acid included, could benefit from a decent BMS.

Update 4/10/06: thanks to everyone for sending email, leaving comments, or for feedback on the EVDL. I’ve updated the chart with a few numbers passed on by folks, added a battery recommended by Dave Brandt. I’ve also put the spreadsheet online for anyone wanting to download it and check my math (promise not to laugh!).

Update 4/21/06: A few folks have written (thanks!) to let me know that most Lithiums these days have a life expectancy. In other words even if you have enough cycle life to theoretically run your EV off of lithiums for 14 years the batteries themselves may only last four or five years. They have also cautioned against believing cycle life claims, this is especially true considering the newness of the tech and limited real-world experience.

Comments 74
  1. jcwinnie    Apr 01, 2006 18:14 PM    #

    Personally, I would go with the Deka, but since these are for Eve, you may want what her Majesty (Quicktime) drives, Jer.

  2. Jerry Halstead    Apr 01, 2006 18:49 PM    #

    Nice video. She still has that spark!

    What do you like about the Deka batteries?

  3. Jack Knopf    Apr 02, 2006 09:15 AM    #

    On a quantity of 4, I can get the 12D2000’s for $275 each shipped.
    In the next few days I will be throwing some serious amps and cycles at them and will get back with you. Later, Jack.

  4. jcwinnie    Apr 02, 2006 10:03 AM    #

    Why Deka? The company, no maintenance, decent life cycles, better equalization, safer (lower cost) shipping, low temp performance. I recently saw on one of the lists where someone, perhaps who could afford risking the investment, was stating a positive experience with Chinese AGMs

  5. — Ryan    Apr 02, 2006 16:30 PM    #

    No mention of the required BMS for the Lithium pack?

  6. — Cor van de Water    Apr 03, 2006 02:18 AM    #

    I use the Chinese AGMs, actually they are a company in Texas, but their manufacturing partner is in China. 12 of the batteries I run would cost you just over $1000 (UB121100) so the risk of a wrong investment is limited.
    Weight would be under 900lbs. I have 26 of these puppies in my truck. Range is 60 miles.

  7. Jerry Halstead    Apr 03, 2006 08:21 AM    #

    Ryan, You are right! I could have sworn I wrote that as part of the article’s conclusion yet it’s not there. I’ll add it.

    Thanks Cor. Do you have a manufacturer name on those or a preferred reseller?

    Also thanks to everyone who has emailed battery info directly (keep ‘em coming!). I plan to update the table information in a day or two.

  8. Dave Brandt    Apr 03, 2006 13:03 PM    #

    Hi, Jerry. The option I’m going with for AGM’s is the 100 Ah PS-12100’s from www.power-sonic.com. They have given me excellent support so far (both sales and technical), and they list the 1-hour rates (100 Ah C20, 55.1 Ah C1, for example). These aren’t high current batteries, but they are available in a wide selection of sizes, and with a 500 amp curtis, you won’t be harming them. I’ve been quoted $123-133 each for the 100 Ah versions, which seems decent. And they have handles! Throwing around a pack of GC batteries without handles, like with my last EV, makes you appreciate those little conveniences! I do plan on adding charge regulators to maintain balance.

  9. — Dan    Apr 03, 2006 13:51 PM    #

    Once you find those batteries sent to you in exchange for advertising, here is how you can display those high-impact ads

  10. jcwinnie    Apr 03, 2006 20:08 PM    #

    “Electric vehicles are still around, but they are for a niche market with a few aficionados and backyard mechanics taking up the fight.” CBC News

  11. Jerry Halstead    Apr 04, 2006 10:57 AM    #

    I think they meant to say:

    ”...but they are for a niche market of intelligent and handsome aficionados and backyard mechanics.”

  12. — Kendall    Apr 04, 2006 11:50 AM    #

    I guess my question about the Deka’s would be what is your definition of an EV racer? I tend to be a bit of a leadfoot and enjoy acceleration but am only looking for normal ICE acceleration. Would these be able to get me to 60mph in 10-15 seconds? (I realize that that is primarily a factor of weight/motor selection so I’ll ask what you project your vehicle will be able to achieve.)

  13. — Woody Becher    Apr 06, 2006 07:28 AM    #

    Does it help to grab opportunity charges inbetween main recharges, or does this reduce battery life more than it’s worth? Since I built my EV lots of people and businesses (mostly bars)have offered to allow me to plug in while I’m there (maybe an hour or so) Does this help or will it count as a cycle and reduce battery life.

  14. Jerry Halstead    Apr 07, 2006 09:00 AM    #

    Hi Woody,

    I don’t think it hurts. Considering that the more you drain (50 vs 80%) the shorter the overall life cycle it stands to reason that by draining less you can cycle more (i.e. more opportunity charges).

    It’s also much better to grab extra charge when you can instead of running the risk of draining the pack too low, which can be quite hard on it.

  15. — Jim    Apr 11, 2006 22:50 PM    #

    Have you looked at Odyssey batteries? I use them in my bike (and lots of other folks I know do as well). They claim a 400 cycle life if fully discharged or 500 at 80%. They can be mounted in odd orientations – most of the BMW riders actually put them in on their side due to the cable lengths of the stock battery cables on BMW RT bikes. Odyssey_world on Ebay seems to be the best folks to get them from (about $60) and the BMWRT discussion board probably has a few hundred posts about these batteries & this dealer.

    Be interested if they have a version that works well for an EV. (I’m starting a conversion of my 84 Fiero this summer…only 34K on the engine, anyone want a good low mileage ICE? )

  16. — Andrew C    Apr 12, 2006 23:24 PM    #

    I was wondering what model of Lithium battery you could use. I want some serious range on my 85 fiero and keep it very lightweight also, Lithium sounds like a winner there

  17. Jerry Halstead    Apr 13, 2006 09:47 AM    #

    Thundersky appears to be the price leader, although I think the price of Valence might include the BMS (hard to tell when reading company literature), which is surely a required additional expense for lithium.

    I’m not very familiar with Kokam, but they are used by the guys at ProEV.

    Even though lithium has made great in-roads in small, portable devices they are still an emerging technology for large scale usage like EVs. The promising factor is with Hybrids gaining lots of momentum there will be increased R&D, advances in technology, and a lowering in prices as it becomes more of a commodity item.

    Heck, my first PC back in ‘84 cost three grand: had 256k memory, two floppies, monochrome display, and didn’t come with a hard drive! Within five years more capable and decked out PCs could be had for half that price.

    This is solely my opinion, but if you want to support future EVs your best bet is to make your “gas” car a hybrid and convince others to buy them as well. An increase in hybrid popularity translates into cheaper and better tech for EVs.

  18. — jim hurst    Apr 15, 2006 20:43 PM    #

    we just got my Dad’s electric car running again. where could we get some lithium batteries check out the link http://www.telegram.com/apps/pbcs.dll/article?AID=/20060414/NEWS/604140526/0/FRONTPAGE

  19. jcwinnie    Apr 16, 2006 14:19 PM    #

    If able to afford lithium, I would hold off a bit. The market is changing drastically. Thundersky has been around the longest, yet may be a bit behind newer developments. In six months we may see a significant change in availability of lithium traction batteries.

  20. — matt perkins    Apr 19, 2006 09:29 AM    #

    Hi Jerry, we are new to EVs and have really been enjoying your site!

    We just acquired an older conversion (‘92 Dodge Colt converted new in ‘92) and have been trying to figure out how to optimize the range. The existing setup is 8 Deka 8C12 batteries (116lbs each). Any ideas why someone would select these? They haven’t been well maintained and our plan is to pull them out and put in something like the J150s. If the goal is to maximize range, should we keep the existing 96V setup or use weight savings to up the voltage? Thanks.

  21. Jerry Halstead    Apr 24, 2006 19:45 PM    #

    Hi Matt,

    If you are sticking with lead acid then the formula is:

    Lead == Range

    8volt, better yet 6volt batteries will provide more range and cycle life than any 12v lead acid batteries. They’ll weigh more, which might be an issue depending on your vehicle’s chassis.

    Plug the numbers for your vehicle into the EV Calculator (link in the article) and experiment with some different battery setups: voltage and types.

    Hey, any pictures, schematics, or crazy stories about your EV that you’d like to share with us?

    Drop me an email.

  22. jcwinnie    Apr 25, 2006 10:24 AM    #

    Crazy stories R Us… I am coming back from a shopping adventure at WalMart and holding up traffic as I drive home in my NEV. A frustrated driver stomps the petal to the metal to shoot by me and a bunch of black smoke issues from the exhaust as the red Ford Probe struggles to respond. And, I thought, “You know, you should see Doctor Halstead about that smoking problem.”

  23. — Tim Iacobucci    Apr 25, 2006 22:54 PM    #

    Have you considered using a Desulfation Pulse Generator if you decide to go with lead acid? Maybe you have already heard of this but I thought I would throw it out there.

  24. Jerry Halstead    Apr 26, 2006 06:26 AM    #

    Hi Tim,

    I used one of those on the first EV. After the first lead acid pack needed replacing I got to thinking, “Gee, what if I got one of them pulse things and made the pack last YEARS longer?”.

    So I plunked down some hard earned cash, got a crazy little plastic box with wires and an LED, and hooked it up. It merrily pulsed away for the second battery pack and then the subsequent third pack.

    All in all I’d have to say that I wish I’d spent the money on candy bars or a bunch of those toys dogs you put in the back window and their head bobs up and down while you drive…

    But, seriously, I’ve since read reviews that these are total bunk and another batch that say they work great. It could be that my use and maintenance of batteries was so good that they never suffered from sulfation and the device had nothing to do.

    Thanks for the link though, maybe others will speak up with their experiences?

    One thing I’ve always meant to try is to use an o’scope to view the pulses coming out of the box and then check the level/shape of them at various stages in the battery pack. It could be that trying to pulse twelve batteries in series just isn’t do-able.

    On the other hand, if anyone would like to buy my old pulse desulfation rig...

  25. — James May    Apr 26, 2006 18:10 PM    #

    You know a funny thing? They say the anode at the end of a string of lead acid batteries tends to wear out in EVs. I wonder whether the actual sharp current changes of the pulse width thingy in the controller actually do this to the anode on the end preferentially, if so, this might mean that, for some reason, sharp current pulses cannot percolate through all the cells. Anyone know if this is possible? it would explain why a long string desulphator wouldn’t work.

  26. Dave Lyon    Apr 29, 2006 18:03 PM    #

    Wow, what a great job you’re doing on this site. I’m afraid most of the electronics is over my head though.

    I’ve been thinking about making an electric car for years. I own a tool and die shop, so I think I can handle the mechanical part. I was thinking about robing parts from an old electric fork lift for my motor and controler. Do you know anything about them? Most run at 48 volts. I’m wondering what obsticles I may run into going this route.

  27. — Nirmal Dhaliwal    May 01, 2006 05:58 AM    #

    An EXCELLENT web site, most informative. I too want to build an EV (probably the first one in Brisbane – Qld – Australia) so will be closely monitoring your new project for ideas. Thankyou for taking the time to list your experiences on the web. Keep up the good work.

    Kind Regards –


  28. — John Croucher    May 08, 2006 10:23 AM    #

    Great site, I have been looking for something like this for a long time.
    I am also from Australia, does anyone know of any Australian suppliers of parts?

    I was also wondering if it would be possible to give a extra boost off the line by using capacitors. I have read that capacitors are often used in applications to compensate for lag associated with lead acid batteries. What I was thinking is that while you are driving these large caps are charged. You slow down then suddenly need to accelerate. Maybe at traffic lights or merging in traffic. The system could sense that you want the extra power from the foot position and releases the energy from the caps into the motor in a burst.


  29. — Nick Smith    May 09, 2006 00:41 AM    #

    John – I am in New Zealand but most of my stuff is coming from Aussie anyway. Bylong Industries in Sydney are the people to talk to about Curtis controllers (www.bylongind.com.au). I am sourcing a lot of smaller parts like relays etc. from Supercheap auto and RS (www.rsaustralia.com). I am fortunate enough to share office space with a forklift spares company (EMC Forklifts) so I am getting contactors, fuses, anderson connectors etc. from them. You may have to hunt around for someone to sell you a motor though! My Uncle is a sparkie so I am getting high voltage stuff like cables and boxes on his account at Ideal Electrical (also in VIC & QLD). Hope this gives you enough to go on.


  30. — James May    May 09, 2006 08:17 AM    #

    Hi John, to see ultracapacitors in practice see
    victor tikhonov’s ev, ultracapacitors page = so cool, just so cool!

  31. — Samuel White    May 09, 2006 09:28 AM    #

    This is a great site, I live in Costa Rica central America, and gas prise are 3.75 a gallon. I´ve been thinking on converting may 71 VW bettle, anyone now what the best kit would be for this car, And also I live in a very hilly area.
    I was wondring what if you used a fiew 28 Volt lithium batterys that Milwaukee used in there new power tools.

  32. — Samuel White    May 09, 2006 10:15 AM    #

    Or Dewalt has there new 36 volt lithium ione batterys, can we use them for a car? Does any body know?

  33. — Samuel White    May 09, 2006 11:43 AM    #

    I´ed say pop a few of this 36 volt lithium ione puppes in a EV and we´ll have cool ride.

  34. Jerry Halstead    May 09, 2006 17:24 PM    #

    Hi Samuel,

    It takes more than a “few” of those battery packs to get things going. When putting together a battery pack for your car you are concerned with voltage AND amp hours.

    So let’s say we wanted a 144vdc system. That means 5 of the 28v packs or 4 of the 36v ones. Not bad.

    But we need energy density to.

    If you use one of the EV calculators you’ll come up with around 100ah (amp hours) or more needed for a decent size EV to get around-town range (all depends on vehicle weight, aerodynamics, rolling resistance, etc…). For the sake of simplicity let’s say that 100ah will do the trick for our car.

    The Milwaukee 28v battery pack clocks in at 3.0 ah and 2.5 pounds. To increase current (and therefore amp hours) you put batteries in parallel. To get our 100ah we’ll need 33 of these batteries wired in parallel!

    But don’t forget, to get the voltage we need requires putting 5 of these battery “blocks” in series. The grand total works out to 5×33 = 165 batteries.

    Total cost: $20,625
    Total weight: 412lbs (not bad)

    If you watched the Monster Garage episode you’ll know that the pain doesn’t end there. How do you charge 165 batteries? They removed ALL of them and plugged each one into it’s own charger. That’s because they use a special charger tailored to keep the batteries from being destroyed. They also had to rig up a pretty extensive buss bar system to “click” all of the batteries into the car.

    Just for giggles I plugged in the numbers for using 5 of these batteries to power Eve. I don’t know if the 3ah is a 20 hour rate or what, so I had to guess a bit. Interestingly the calculator determined that I could make it 3 miles (I think that’s 100% discharge). No indication how often this could be done or if the batteries would explode or die in the process. ’:^)

  35. — James    May 10, 2006 18:54 PM    #

    The DC27-850 by Everready seems on the surface to be more cost efficient and weight-efficient than the J-150, even at half the lifetime, because at $660 for a pack you can buy two packs for under what one pack of J-150’s cost. Not to mention the 340 pound weight savings…Or am I just being El Cheapo Grande??

    Also, how long does one expect to run an EV before deciding to build/buy something different?? I would think that about the time your pack goes dead (in 6.2 yrs approx) that one would want to try another approach to EV since the Lithium-Ion tech is coming along so nicely…if prices continue to drop at a significant rate I can see where in about 6 years chances are high that you’d want to go to a different battery pack anyway.

  36. Jerry Halstead    May 10, 2006 19:24 PM    #

    Hi James,

    Where are you finding the Eveready? I’ve seen it listed on Uve’s battery page (hasn’t been updated in a while) but can’t seem to find it in a google search except for a few google ad-word squatter sites.

    Also, it’s a flooded and I’m shooting to try a non-flooded this time.

    The reason I think price shouldn’t be the sole gauge in picking a battery is that my time is worth money. Not that I don’t waste time, but some things that are more fun to waste time on. Messing with a questionable batteries and changing out the whole pack every year or couple of years just isn’t one of them.

    I already went down that route with the second battery pack for our first EV: bought cheap no-name batts that saved about $5 each and ended up replacing them within a year.

    Besides, look how much time I spend over analyzing these things! Can you imagine me doing this every year or two? I’d go crazy.

  37. — jim hurst    May 10, 2006 19:35 PM    #

    we have been waiting 30 years for cheaper, better batteries :{

  38. — John Westlund    May 10, 2006 22:30 PM    #

    We had the better batteries 10 years ago. The Ovonic NiMH. 70 wh/kg specific capacity, 1,750 cycles to 100% depth of discharge. Robert Stemple, chairman of Energy Conversion Devices, quoted them at $150/kWh for a production run of 20,000 cars.

    General Motors, not wishing to see the electric car go mainstream, sold the patent to Chevron Texaco. Chevron Texaco vigourously protects this battery and has sued Toyota for making a similar design. Further, with the oil company winning that case, it can now restrict the maximum AH size of the batteries to 10 AH. This prevents them from ever being used in a road EV, as it is not practical to go above 400V or so and NiMH cannot be charged in parallel with ease. Further, this oil company is responsible for about half of the price premiums on Today’s hybrids; they charge $1,200/kWh for the battery when it could be much cheaper!

    At 70 wh/kg, a midsize car with attention to aerodynamics could have 200+ miles highway range with a 500 kg, 36 kWh pack costing $5,600 and lasting well in excess of 300,000 miles in theory. This battery has been denied to us. This battery would allow hobbyists to make 120-150 mile range conversions a norm, and 200-300 mile range conversions a possibility.

  39. — Michael Terry    May 12, 2006 14:42 PM    #

    Thanks for writing this informative blog.

    I’m thinking of switching from 8 volt flooded to the Horizon 12 volt batteries on my conversion. It would lighten my pack by more than 325 lbs. I also use a Manzanita Micro Charger.

    The folks at EaglePischer/ Horizon are not sure that the Manzanita charger can correctly charge those batteries. Do any readers of this blog know of anyone who has used the horizon batteries? If so what did they use to charge them?

    I can pass along the charging instructions they sent me to anyone who is interested.

  40. — Bill H    May 12, 2006 18:52 PM    #


    Looks like Ovonic NiMH are being produced, have you seen this quote “Ovonic Battery has recently expanded the scope of its licenses granted to Cobasys LLC — its 50-50 Ovonic NiMH battery manufacturing joint venture with Chevron Technology Ventures LLC — to position Cobasys to take advantage of the growing demand for prismatic NiMH batteries and to enable it to address a full range of prismatic battery opportunities. To learn more about Cobasys, visit its website at www.cobasys.com .” from http://ovonic.com/sol_srv/3_4_battery_sol/battery_sol.htm ?

    I went to cobasys’ web site and looks like they do have EV products.

    Found lots of info when googling for Ovonic NiMH .


  41. — John Westlund    May 12, 2006 21:00 PM    #

    The large AH batteries Cobasys has listed on their website that are suitable for EVs are available to OEM only; you cannot buy them.

    Panasonic and other companies used to make and sell NiMH EV batteries to entities other than OEMs. They can no longer make and sell them after the successful lawsuit Chevron brought against them. But with their licensing agreement with Chevron, they do sell hybrid batteries and pay royalties, batteries under 10 AH…

  42. — James May    May 13, 2006 07:46 AM    #

    Hi John

    I share your sense of outrage that the patent system can be abused to prevent such a useful and potentially clean technology as NiMH from being practially available. What GM did when they sold the patent to Chevron was to sabotage EVs as an alternative to ICE cars. I am frankly glad that Toyota stole their thunder with the hybrid, they didn’t deserve it. They’ve made their bed with their high margin, inefficient SUVs and must now lie in it! For shame!

  43. — JohnG    May 13, 2006 13:18 PM    #


    After two weeks for hard work on the PC, internet, and with Uve’s calculators, I now have one of the largest battery spread sheets that I have ever seen. Most of the prices are reasonabally current.

    It compares mass, power, amps, cost, and space for many Trojan, US Battery, Concorde, Optima, and Hawker cells with the Ovonic’s thrown in for good measure.

    If anyone could benefit from this, just let me know.

  44. John Westlund    May 13, 2006 16:57 PM    #

    I’ll take a spreadsheet.


    Eliminate the [nospam] and place the proper characters where designated.

  45. — Michael Terry    May 15, 2006 16:22 PM    #

    I could make use of the spreadsheeet, thanks

  46. — John Jackson    May 15, 2006 16:27 PM    #

    Hi everyone,
    I’m new here but have been following the updates for a month or so. Great site! I’m a couple years away from building my own EV and in the meantime will be working on electric bikes and trikes. I was also interested in the new Dewalt 36V lithiums but never was able to find an amp-hour rating however I did receive some info from their tech support that I’ll pass on. See the link. DEW27106 (Drill Powe#1ADACA.pdf (3623.5 KB) It will show power ratings and appears that the battery is capable of 20A+ output. Not certain for how long that’s sustainable. Also on the subject of patents. They are generally only good for fourteen or twenty years from the date first granted. I attempted to look up the Ovonics patent and found several. Most of them dated from sometime in the 90’s. So I’m guessing that anyone should be able to reproduce their technology within the next 5 to 10 years if they wish. I would guess their technology will be far behind by that time however. Keep up the good work. I truly enjoy your site.
    John J.

  47. — John Carter    May 15, 2006 18:45 PM    #

    I would also like a copy of that spreadsheet. jcarter[at]parker.com

  48. John Westlund    May 16, 2006 18:32 PM    #

    For the ev suitable NiMH battery, that patent won’t be available until like… 2018? Peak oil is likely going to cause a catastrophic shortage well before then, but this shortage will allow the industry to maximize profits. We need production of viable EVs now, not 5 or 10 years from now. Sadly, nothing is being done despite the technology being right there.

  49. Brian Osburn    May 17, 2006 13:06 PM    #

    Okay…remember the TV show “Sucking Amps”. Rod (the star) has told me that 6-volts are the way to go. One reason was that they were easy to charge. So Jerry, if you go with the Trojan 105s, what type of charging system would you employ? I hope someone can answer this very important question for me as the local high school here appears interested in doing all the work on this project for me. (HalleluuuuuhoooJAH)!

  50. — James May    May 17, 2006 16:44 PM    #

    Hi Brian,

    I am running 16 of those (well T6220 which are very similar.) I am using a 3 stage Zivan charger nominally 96V. It charges then up from a 60% DOD in about 5 hours. I am sure there are loads of similar. You can search on the EValbum.

  51. — Ray    May 23, 2006 20:47 PM    #

    Hey Jerry found this site and thought you might like to look not sure the cost..

  52. — John Croucher    May 28, 2006 04:35 AM    #

    I saw an electric car on TV where they said it uses around 7,000 HAND MADE lithium batteries. Could this be an alternative to get the batteries people need, to make them at home by hand?

  53. — Matt    May 31, 2006 07:02 AM    #

    Hey Jerry,
    TOP site. Have you an opinion on the Trojan L16H 6V for suitability?

  54. Jerry Halstead    May 31, 2006 12:06 PM    #

    Hey Ray, cool batts. Did you find any pricing or availability? When I see “for government/space” it sets off all kinds of wallet alarms.

    Hi John,

    Well, not sure how many folks have access to the raw materials for making their own lithium batteries. Plus there’s the safety issues to consider.

    Or do you mean buying off the shelf Lithium (AA’s) and wiring them together? I’ve heard of some folks doing this, or something similar. A few things come to mind:

    * are they CRAZY?!

    * that’s a lot of wiring

    * that’s a lot of possible failure points (the idea troubleshooting 7,000 batteries and 14,000 connections sends shudders up my spine)

    * you need battery management for lithiums, maybe not every battery, but quite a few of them…more money

    Still, if you have the time/money/teenagers (i.e. cheap labor) to pull this off it might be an interesting project.

    Hi Matt,

    If you have the space for it that would work, but it’s a HUGE battery. 120 pounds each, I’d need twenty of them for a 144v system, for a total of 2,400lbs in battery weight alone.

  55. — James May    May 31, 2006 12:59 PM    #

    Beetles have steering boxes not rack and pinion though

  56. — Matt    May 31, 2006 18:05 PM    #

    For a range orientated vehicle do you think the much higher weight of the L16H would cancel out the advantage of so much onboard energy? Would a 20hp rated electric motor be able to pull upwards of 4000lbs up an incline…

  57. Jerry Halstead    Jun 01, 2006 22:47 PM    #


    It depends if the donor vehicle can handle the extra weight. Run the numbers using the L16 and the T105 (or US equivalent) and see what you get. There’s a link to the EV Calculator above.

  58. — James May    Jun 02, 2006 07:14 AM    #

    Matt, I think that if you put larger batteries in your car, you will always increase range as you increase the charge density of the vehicle (battery weight increasing while the weight of the other parts of the vehicle remaining the same). This will however affect your acceleration and as Jerry points out, you don’t want to squash your car or make it dangerous with too much weight.

  59. — JohnG    Jun 10, 2006 20:32 PM    #

    What it really comes down to with PbNa batteries (“normal” deep-cycle lead-acid) is how many pounds (Kg) of lead do you have? The more lead, the longer the range. Double the lead, double the range.

    Acceleration may be reduced, but that depends on the batteries. GOOD wet cell deep cycle lead batteries with high capacities will yeild nearly the same acceleration as lighter not-as-good dry or gell lead acids because they simply cannot sustain high current loads for very long w/o the voltage dropping.

    Granted with 1/4 the weight, gell packs do have a distinct advantage in acceleration, but the range is reduced to the point that they are unsuitable for use in all but the very lightest vehicles requiring high voltage packs (144Vdc or greater).

  60. — James Edmonson    Jun 13, 2006 21:13 PM    #

    Jerry, I am starting my third conversion and have use both lead acid and AGM’s in the past. This time i am converting a 2000 Ford Ranger PU and plan on useing Trojan L16H Batteries. These 6 volt puppies have a 420 AH rating and in a set of 24 at 144volts i hope to get 100+ miles/charge and be able to carry a 500lb payload. The down side is the size. they weigh 121 lbs each and are nearly 17 inches high. However, their length and width dimensions are nearly identical to the T 125 makeing replacement later (if they fail) with more conventional batteries possible. Did you come across these batteries or any one with experience with them in your research? Any thoughts or suggestions would be appreciated. Thanks, James


  61. — John Westlund    Jun 14, 2006 07:06 AM    #

    You could get more than 100 miles if you did a shitload of aeromods. Maybe 150 miles…

    The big uncertainties are cycle life and max dishcharge current. I don’t know many conversions using these. The T145s, although less weight, have cycle life around 800 to 70% DoD. If cost isn’t a factor, I’d try 36-40 of T145s.

    The L16H do look very interesting though. They’d easily give you 100 miles range at 60 mph.

    If you do aeromods, that range could increase over 50%, double with LRR tires and other efficiency improvements PLUS aeromods.

    If you’re going to load the truck with batteries, why not go all out for max range?

    Below is an article describing how Phil Knox improved his highway fuel economy nearly 30% by building aerodynamic modifications to his truck. I’ll link it again:


    The same would apply to an EV’s range, and then some(Peukert’s losses and such).

    I recommend you do the following.

    In order to maximize range, the following aerodynamic modifications could be done with sheetmetal, plastic, and fiberglass:

    -aeroshell, a tapered bed cover made of fiberglass
    -underbelly, made of corrugated plastic
    -grille block, made of corrugated plastic
    -rear wheel skirts, made of sheet metal
    -front air dam, made of sheet metal
    -side skirts, made of sheet metal
    -rear boattail, made of sheet metal
    -wheel covers, made of corrugated plastic
    build shaved door handles from parts found in junkyard, weld a sheetmetal backing plate to where the door handles were

    This may get the drag coefficient down to around .24.28.

    Further, the brakes can be adjusted so that they don’t drag.

    You’ll need some low rolling restiance tires. With all that weight in that truck, they will greatly improve efficiency given how much losses rolling force will incur from such weight!

    Alignment? 0 camber, 0 toe in/out.

    Just to be on the safe side, continue to expect 100 miles range, but theoretically, with all of those modifications, you would do 200 miles per charge at 60 mph!

    Same range as a gas car. ON LEAD ACID!

  62. — Dan    Jun 20, 2006 02:40 AM    #

    Just to through it out there… Keep in mind the cost of suspension system changes and modification needed because of excessive weight. Some batteries may be $400 cheaper, but are you going to put $500 into getting beefier shocks? And, as already mentioned, it takes less energy to push less weight. Heavier vehicles also take more effort to stop. (A half second in breaking distance might make the difference between whether or not you have to replace the battery supply again… ohh, and the car.)
    I enjoyed your website. Thanks for all your effort to share your experience!

  63. kert    Jun 20, 2006 09:56 AM    #

    look at the new generation of lithium-ion powertools. bottom of the page i linked to.
    these 18-36V 2-3aH packs run from $100-$170, bosch being the most expensive.
    DeWalt ones have the A123systems nano-phospate tech inside and run $150 for the pack.
    Its worth checking out

  64. kert    Jun 20, 2006 10:03 AM    #

    duh i shoulda read more carefully above, you already did the calcs for this option.

  65. — Barry    Jul 02, 2006 15:36 PM    #

    Jerry, are you aware of the magnesium batteries from Idea One Inc? From what I have seen , this is the most promising. I remains a concern that information on the progress is not available?

  66. — mike    Jul 11, 2006 22:34 PM    #

    I’d like to get a copy of the battery spreadsheet if it’s not too late. I’m a new visitor to this site. thanks.

  67. — Matt Perkins    Aug 15, 2006 16:42 PM    #

    Has anyone tried to use the Ovonic NiMH available from evbones.com?

  68. — Nagorak    Aug 18, 2006 01:33 AM    #

    First of all, I’d like to say that I like your spreadsheet, and I expect it could very valuable in helping me decide on batteries for use in my own EV conversion, which is currently in the planning stages. I’m still new to this whole thing and clearly have a lot to learn and a long way to go, but hopefully when the time comes it can be of some help.

    I do have a question that is somewhat off topic, so hopefully you guys will humor me. It has to do with batteries, but does not relate to EVs per se, but rather to their use in a solar array.

    Recently I made the mistake of flipping the battery disconnect on my solar array, which erased the previous configuration settings and I was forced to set everything up again (previously it was configured by the installer).

    Anyway, as I was setting everything up I noticed the batteries in the battery bank were listed as having a float charge of 13.2 to 13.4 v (they are sealed AGM 12v batteries wired in series to create 48v). My question is, from a pure longevity standpoint, whether it would better to run these at 13.2 or slightly higher at 13.4v? The batteries are rarely discharged so they should more or less be maintained at this float level.

  69. Jack Knopf    Oct 19, 2006 16:26 PM    #

    Starting to get a little real world use of the Horizon 12D2000’s. After having two of them open up when I applied the first 1000 amp load, I finally got 6 of them in my Chevelle that will handle the big amps. The last two Fridays, I went Drag Racing with the 12D2000’s. Both times my generator failed so I ran 3 runs each Friday without charging in between runs. At 72V, in a Heavy 4 door 64 Chevelle, my 1/8 mile times were 13.27, 13.39, 13.49, 13.52, 13.52 and 13.57. All around 48 mph. Each night I made 3 runs without charging and the times stayed right up there. If you can get some good 12D2000’s that won’t open up, they are impressive!

  70. — todd s.    Oct 25, 2006 13:52 PM    #


    I understand you want all electric but would it be possible to take a couple 100 amp alternators on a small gas engine to power the car? You mention 300 Amps at times it seems that several of these could create enough power. What am I missing?


  71. — James May    Oct 26, 2006 08:16 AM    #

    Hi Todd.

    What you describe is called a series hybrid. It’s probably worth doing a google search to see what people have come up with. David Anderson’s comment shows he’s interested in series hybrids as well. One of my favorite ideas is a simple parallel hybrid made from a small car-like 4×4. You would disconnect he front and back axles and run the front wheels from the petrol (gas) engine and the rear wheels from a direct drive motor. You’d have to have enough torque to drive the vehicle electric only at low speed. You can charge the batteries on the motorway (freeway).

  72. — Ken Barton    Nov 18, 2006 04:29 AM    #

    Many thanks for a great site. Also book marked your 1st. Just saw a DVD called “Death of the Electric Car”.....GM should be ashamed. I’m 74 and have always wanted to “Do It”...thanks to you I am encouraged and am gonna give it a try…lookin’ for a donor car.

    Wil keep you posted.


  73. — Scott    Jan 02, 2007 19:40 PM    #

    Here is a list of the only manufacturers of NiMH batteries that would be approprate for EVs. I have looked into these companies, and am icluding the contact information I have found for them, but I am not inquiring about availability. So anyone who would like to take the time, feel free. From what I saw, each one has different battery offerings, including Lithium!!

    1-8-1, Nishishinbashi, Minato-ku, Tokyo, 105-0003, Japan
    Phone: 81-3-3597-2200

    Saft Industrial Battery Group
    12, rue Sadi Carnot
    93170 Bagnolet – France
    Tel: +33 1 49 93 19 18
    Fax: +33 1 49 93 19 64

  74. tim c    Jan 05, 2007 23:36 PM    #

    i wish there was a ev club in ohio