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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!

EV Batteries · 29 September 05

Transmission Housing End

Now that the engine and most of the extra parts are out of Eve I’m starting to think about next steps. Right at the top of the list is figuring out what kind of batteries to use, how many, and where to put all of them.

On the first EV I went with lead acid and the more that I look into the types (and prices) of batteries these days the more I’m starting to think that I’ll be using lead acid again.

Ken Norwick and I exchanged emails two weeks ago and his advice was to stick with lead acid until the proliferation of Hybrids starts to drive down the prices and increases availability of the more advanced battery technologies. Bang for the buck, lead acid still rules.

Over the course of the next week or so I’ll be looking into batteries and kind of blurting out observations, opinions and maybe share some links along the way. There is so much information it’s really hard to pick a point to start (or end).

Lead Acid

Lead acid is probably the best you can get in the price performance category. Proper deep cycle batteries provide plenty of range and long cycle life, which correlates to more years of service. The rule of thumb has always been LEAD==RANGE: more lead, more range.

If you have the room go with 6 volt batteries, like the Trojan T105 or US Battery US125. These are heavy duty deep cycle batteries with 600 or greater cycle life (number of 80% discharges). Failing that some of the manufacturers offer 8 volt deep cycle batteries.

Our first EV used 12 Trojan SCS225, which is a 12 volt battery. I used them lightly and treated them pretty well and could just about squeeze 3 years from the pack. Of course I had a short commute, longer commuting over the same terrain would probably have shortened the life span.

Quite often I hear of folks heading down to the nearest *Mart and picking up marine batteries or, even worse, car batteries. That’s a good way to waste your money and time. A car battery is designed for short bursts of power and will quickly fail after regular EV use. The deep cycle batteries used for an EV (sometimes called traction batteries) are designed for frequent, deep draining, down to 80% capacity.

Marine batteries lie somewhere between a true deep cycle and a car battery. My EVs second set were marine batteries ordered from a nearby distributor. I saved about $6 cheaper per battery, a whopping $72. They barely lasted a year…no savings at all.

So what’s the deal with batteries, why is this so tough?

Battery chemistry is neither exact or entirely predictable. Two identical battery cells may, over time, behave differently. In an ideal world you would have one battery with one cell and it would generate all of the voltage you need. Instead, lead acid battery cells generally produce a little over 2 volts and you need six of them just to make a 12 volt car battery.

Six Kids

Those six cells in the 12v battery are like sextuplets: they may look the same, but underneath the freckles and identical smiles are slightly different chemistries. After a year or so one of the sextuplets starts going to bed late and waking up even later, missing out on breakfast, eating doritos late into the night, and generally straying from the pack. Same thing with battery cells (except the dorito part)...who knows why they do it, but the end result is that over time the six cells are no longer equal.

I’m not sure what to do with the stray sextuplet but for EV batteries we perform an equalization charge from time to time. This is done by charging the batteries, like we normally do, and then continuing the charge for an extended period. Slowly the weaker battery cell gets recharged, while the good cells just sit around and boil off their frustrations. I suppose it’s like taking the sextuplets to Church.

While lead acid has the price/performance edge and is time-tested technology it also requires regular maintenance. The water levels need to be checked, specific gravity measured, and the occassional equalization performed. Every couple of weeks or once a month, depending on your usage.

Is there a better way? Maybe…


I’ve only read about these and each time they tempt me to cross over to the “waterless” side. AGM batteries are a form of sealed lead acid using what is called a “glass mat” for storing the electrolyte. Since these batteries are sealed and don’t need maintenance they can be located practically anywhere.

AGMs have low internal resistance, which translates into quicker charging and discharging without generating as much heat. The downsides, near as I can figure, are that they cost 2 to 3 times as much as lead, don’t like to be discharged as deeply, and you need special circuitry to charge them properly.

Frog Chin

Being sealed they shouldn’t be overcharged because it would cause heating and venting of the gasses, breaking the seal. To insure that the AGMs live a long, healthy life specialized circuits are attached to each battery which monitor the charge voltage across the battery and when it is full, bypasses current around the battery to protect it.

So what’s not to love? A little extra cost for batteries, some bucks for safety circuits, but no watering or fussing.

Let’s do some fuzzy math. The SCS225 battery has a 20 hour rating of 125ah and costs $85. An Optima has a rating of 100ah and costs $140. Let’s say that with a limit of 80% depth of discharge (dod) the SCS225 is really more like 102ah, while an Optima which prefers 50% dod can only do 50ah. Right off the bat we need to buy twice as many Optimas to equal the amp hours of an SCS225, $280 vs $85 per battery or $3,360 vs $1,020 to equip the EV.

Not only that but I’d have to find room for twice as many batteries and buy 24 regulators. Suddenly watering the batteries every once in a while doesn’t sound so bad.

Of course my data, math, and assumptions could all be flawed. I’m basing the price/capacity off of this chart and it may be out of date. I’m also guessing that both of these batteries are otherwise equal and have the same, relatively low, cycle life (~200).

DCS-100L Battery

There are other AGM batteries out there and some might be more suited to an EV. The Dynasty DCS-100L looks interesting. I haven’t done much research but the higher cycle life is attractive. If I plug it into the EV Calculator page it also looks good.

This is the stage of the conversion where you really ought to know what it is you need. Like I’ve mentioned I don’t need much range. In fact buying batteries that provide 50-70 miles of range would be a waste of money. I drive 8 miles round trip most days, maybe 20 miles if I run an errand. If we take worst case winter driving with 1/3 less capacity an average range of 30 miles should work.

Equipping your EV for more range means higher cost, a heavier vehicle, and more work trying to jam extra batteries into the chassis. If you don’t actually NEED the range then you are wasting energy hauling unneeded weight around (although your wallet will be lighter).

One reason I’m not giving up completely on the AGM idea is flexibility in layout. The other night I was under the car looking at what it will take to remove the gas tank and realized that its old location might make an ideal spot for a pack of batteries. Only about seven or eight inches deep, which means they’d have to be on their sides. It’s a great spot for weight distribution and center of gravity.

I realize that I haven’t covered some of the other batteries: NiCad, NiMh, Lithium, and the other acronyms bouncing around battery world. If I come across sufficient information about these (along with pricing) I’ll write up a new article just for them. If you have any links or information please feel free to drop me a note.

8 volt graphic

While we are thinking about batteries I’ve put together a little online Battery Layout Tool.

Tell it how many battery boxes you want, how many batteries to put in each box, along with what size and type of battery you’ll be using. The tool then creates an interactive page to let you experiment with the layouts. You can resize the boxes, drag the batteries and boxes around the page, and when everything is just right print out (or screen capture) the page.

Comments 78
  1. jcwinnie    Oct 01, 2005 15:33 PM    #
    Re: Superior PLI

    In the good ole USA? Well, you could ask someone at Cinema Vehicles to ask Chaz.

    But, boy (hawk-sput), you all sure you ain’t wanting to buy Valence?
  2. Jerry Halstead    Oct 02, 2005 09:47 AM    #
    Uh, lessee, I can buy two full sets of lead acid batteries for the price of a single Valence Lithium.

    You sure that you aren’t a Valence shill? ”:^)
  3. jcwinnie    Nov 02, 2005 17:26 PM    #
    Ready, to make that run to Cambridge for batteries, Jerry?
  4. Jerry Halstead    Nov 02, 2005 18:04 PM    #
    Are you buying? See you there!
  5. — Woody Becher    Jan 19, 2006 16:56 PM    #
    What terminal type did you use with your 12V Trojans, Universal or one of the threaded/wingnut terminals? Does it matter?
  6. Jerry Halstead    Jan 20, 2006 12:59 PM    #
    I used threaded terminal type, replacing the wingnuts with proper nuts and a locking washer on top just to be sure.
  7. — James May    Jan 21, 2006 17:08 PM    #
    WOW! you have to see this!
  8. — Woody Becher    Mar 29, 2006 08:33 AM    #

    How do you check the level in the Trojan batteries? I look in and see water, but I don’t really know how full it should be.

  9. — James May    Mar 29, 2006 13:02 PM    #

    So do I!

    They have got a information about it, I believe it is supposed to be a certain height above the plates. Trojan watering
    I just go round squirting the same amount of water in each one using a syringe.

  10. Jerry Halstead    Mar 30, 2006 18:19 PM    #

    Hi Woody,

    For my Trojan SCS-225 batteries I started off crawling around with a gallon of distilled water and a plastic turkey baster, topping all of the cells off to the very bottom of the plastic fill holes. On the 225’s the bottom of the fill hole plastic has grooves in it so that even if the water touches it the vapors can still escape.

    I eventually splurged and bought a plastic battery filler. It’s spring loaded: put the nozzle in the battery hole, press down, and then most of the time it shuts off when the battery is full.

  11. — Doug Golde    May 13, 2006 12:23 PM    #


    I would love to know where you buy SCS225’s for $85. I need 6 for a GEM car.


  12. Joe Porcelli    Jun 11, 2006 14:29 PM    #

    Hi Jerry, great atricle!
    We are building a Datsun 280Z EV, with an Electro automotive kit, they recommend 24 6 volt batteries for this kit, but after reading your article the 12 volt (deep cycle) may be a better choice for mainly weight reasons even though there’s plenty of room under the hood where the Z’s inline 6 used to be, for lots of batteries, but I really don’t want an overweight Z. Theres room in the back for about 6 batteries since the fuel tank is out. It would be nice to get about a 50 mile range. Would you go with the 6v or 12v. Thanks for your suggestions.

    Operation Z

  13. — John Westlund    Jun 11, 2006 17:40 PM    #

    I wouldn’t go with flooded batteries for a Z car unless this is for a first conversion.

    Sealed lead acid batteries will give far more power with less weight. 24 Trojan T105 6V batteries is 1,464 lbs! That might give a Z car 80 miles range on up. But it would only provide ~50 kW of battery power. You’d have a 144V system, with a top speed around 100 mph.

    In contrast, 24 Exide Orbitals would weigh 984 pounds, provide over 350 kW of battery power(far more than your Curtis and 9” motor will ever use), and might give you a 40-50 mile range. Much less weight, much better power. But AGMs need a good charging scheme and regulators, something your kit probably wouldn’t provide, and adds to the cost.

    If you go to 12V flooded batteries, they have the downside of not being able to deliver the amount of power 6V batteries do(draw 400-500 amp currents from 12V batteries and you will dramatically shorten their life, whereas you can do that with 6V batteries). However, they might be a good compromise. But range might not be near as good. Range is influenced by how many pounds of batteries you have on board. A car with 700 pounds of batteries will go roughly half as far as a car with 1,400 pounds of batteries.

    If I had already decided on this kit, I would go with the 6V batteries. More range. More amps. But then again, I’m not a fan of kits. A car like this deserves a Zilla and AGMs!

    Do you have a website so I can keep up with your project? I am very interested. The 280Z makes an excellent conversion.

  14. Joe Porcelli    Jun 12, 2006 02:35 AM    #

    Thanks for your comments John, and yes, It is going to be our first conversion. After thinking it over and all the added extra weight with the 6v batteries I may now consider 18 8v batteries, probably go with the Trojan T890 or the US8VGC to get some decent range. But I’m always open for suggestions.

  15. — John Westlund    Jun 12, 2006 03:40 AM    #

    US8VGC are cheap! I wouldn’t try drawing more than 300 amps from them though.

    I may use those in my first conversion as well.

    They’ll sag to about 7V under 300A load. So, 300A*7V*18 = 37,800W.

    Motor is about 88% efficient, controller 95% efficient. W/1000*1.35 = HP

    So expect around 43 peak horsepower from the motor.

  16. — James May    Jun 12, 2006 07:16 AM    #

    I have heard that the 8V Golf cart batteries are not quite as robust as the 6V ones, probably still pretty good. I am running 16 6V Trojans and they can take quite a lot of abuse. My car is heavy though!

  17. Jerry    Jun 12, 2006 07:54 AM    #

    For range and cycle life the 6 volt deep cycle is the proven winner in lead.

    12 volt is more convenient and takes less space, but you “pay” for this: you’ll be replacing them more often, maybe every 3 yrs instead of 6, and will have less range.

    According to folks on the EV list the Trojan J150 (12v) has the same plates as the T105 (6v), so it’s like Trojan made a 12v battery out of two 6v batteries for you. I suspect it’s not that simple but I don’t have any data to say one way or the other.

    If you are optimizing for range and don’t have lots of money to spend then the only real choice is the 6v lead or equivalent.

  18. — Joe    Jun 12, 2006 15:01 PM    #

    So I guess the 8 volt Trojan (T890) would not be advisible to save 250+ lbs. and some extra space.

  19. Jerry    Jun 12, 2006 15:16 PM    #


    You might want to peruse the EVAlbum for folks who:
    a) have converted a similar car
    b) are using 8volt batteries

    Drop them an email and ask what they think about the battery/ev.

    This is what I did when I was considering gel cells and the information I got was invaluable.

    To get you started:


  20. — Rick G    Jun 14, 2006 19:42 PM    #

    I’m just in the planning stage – like everyone else, I’ve been reading about and trying to understand the battery dilemma. I’m looking for RANGE and have plenty of room for batteries (truck). Why the Trogan T105? Why not the T125 or the T145?

  21. Joe    Jun 14, 2006 23:55 PM    #

    Possibly the weight factor: on
    24 T105’s=1488 lbs.
    T125’s=1584 lbs.
    T145’s=1728 lbs.

  22. — James May    Jun 15, 2006 07:12 AM    #

    much cheaper!

  23. — Rick G    Jun 15, 2006 17:44 PM    #

    Thanks – in this case, bigger is ALWAYS better.

  24. — John Westlund    Jun 15, 2006 23:43 PM    #

    Until you reach the GVWR. But there are ways to compensate for that, like leaf springs, tires that can handle the weight, stronger brakes, ect.

  25. Jerry Halstead    Jun 16, 2006 10:02 AM    #

    After much more flailing (not all of it my own) I’m now considering spending the extra money to buy the Odyssey/Hawker PC2150 (pdf) AGM. Everything I’ve read on the EVList points to the Hawker batteries as being well built, forgiving of abuse, and long lasting.

    Anyone have experience with them: good, bad, or otherwise?

    The next challenge is finding someone to sell them to me. This has been much tougher than I anticipated.

  26. — Rick G    Jun 17, 2006 18:47 PM    #

    Sorry – I just re-read what I last wrote – I ment to say Bigger is NOT always better. If the range gain is negligible – less expensive is better.

  27. — Jerome A    Jun 18, 2006 18:43 PM    #

    I went down to my local (Ft. Lauderdale, FL) Batteries Plus store, and they had 2 of the Odyssey PC2150 setting on the shelf for $299 each. The sales rep. said that he could order a set of 12 for me, at a much discounted rate, and have them ready for pick-up in 3 days. Order on Monday, pickup on Thursday. I am still looking for a vehicle, so I told him I would be back… Since this is my first EV, I think I might look for a cheaper battery.

  28. — jim hurst    Jun 18, 2006 19:23 PM    #

    there is a batteries plus in Nashua, but $299 is a big pile of coin

  29. — John Westlund    Jun 18, 2006 20:45 PM    #

    Jerome A, if you want a cheap AGM, you might want to try the Universal Battery UB121100. 110 AH at the 20 hour rate, 80 AH at the 1 hour rate, 720A max current, .004 Ohm internal resistance, 73 pounds each, 12V nominal. $85 each.


    I don’t know about the max current itself, but members on the EV list have verified the AH claims and internal resistance claims. But they never needed to take more than 200A draws from the batteries, so their ability to take high discharges is not fully known.

    I’m thinking of using a set in my first conversion. Perhaps 156V pack, homeade regulaters using Lee Hart’s design, homeade Bonn charger modified to accomodate the last 10% of charging, 5-speed contactor controller, and Prestolite motor.

    This might allow a $2,000-3,000 conversion that can do 0-60 mph in under 10 seconds, top out at over 100 mph, 50+ miles highway range. I’d be more than happy with 60 mph top speed, 0-60 in 30 seconds, and 20 miles range for that price, but hell, simulations show I could get those first specs with such a setup, provided I have AGMs. The only downsides are that the contactor controller may pose as a safety hazard and that I expect to kill my first battery pack. However, 13 UB AGMs is cheaper than even 16 Trojan T105 floodeds, and about the same weight!

    After the initial conversion is on the road, I can save for a LV Zilla, WarP 9” motor, and a PFC charger with Rudman regs. With aeromods, more efficient motor, and LRR tires, the highway range may increase to 80+ miles. With Zilla and 9” motor, 0-60 in 6 seconds, like John Wayland’s Blue Meanie, 120+ top speed. By then, if the batteries can’t give high enough currents for the power I’d want, I might have the money to switch to those above mentioned Hawkers. That would be a cheap, long range, high performance conversion all in one.

  30. Joe    Jun 19, 2006 02:14 AM    #

    Does anyone know the Interstate Battery/US Battery Equivalent to the Trojan J150?, I get a decent break on Interstate batteries (since I have an account with them). Maybe the EV-145? or U1450?...who knows? Anyway after thinking it over we really don’t want to make this 280Z-EV a 3600+ lb. hunk of lead and would beat the crap out of the suspension among other things. 3100 lbs. sounds much better, I realize range and battery life will be reduced but were leaning in the 12v direction at this point.

  31. — John Westlund    Jun 19, 2006 03:39 AM    #

    If this were my conversion, I wouldn’t even use a kit.

    I’d get a PFC20 charger, Zilla 1k controller, WarP 9” motor, and a pack of AGMs. Although the kit might come with everything prefabricated, if you design your own adaptor and battery boxes/racks, motor mounts, and such, and build them, you will have a lot more money left over for other things like more powerful motors and controllers, and maybe even better batteries. Also, if you go the no-kit route, you get to choose what parts you want to have in the EV, instead of having everything layed out for you. The downside is that more trouble shooting may be required, than if you had just bought the kit itself.

    If you go with 12V batteries, I’d avoid floodies altogether and use AGMs with some regulators. Say, a 192V pack of UB121100 AGM batteries, and a PFC charger with the proper regulators.

    Although I earlier recommended shying away from AGMs for a first conversion, the Universal battery UB121100 are roughly as cheap as 6V floodeds per opound of battery.

    Floodies are usually a good first choice due to their forgiveness to mistakes and being relatively inexpensive compared with AGMs. However, there are AGMs that are cost competitive. It is very common for those new to EVs to ‘kill’ their first battery pack, so expect it to happen. AGMs are suaully not recommeded for a first conversion for this reason coupled wioth their price, but those AGMs I mentioned earlier are no more pricey than cheap Trojan floodeds.

    Maybe you should consider a 192V pack of UB121100 batteries, HV Zilla 1k, 9” motor, PFC charger, and regs. You’d have a sporty conversion around 3,000-3,100 pounds weight, and with an imposed 500 amp draw limit from the batteries with the Zilla and 1,000 motor amp and 170 motor volt limit with the Zilla, you could have roughly 80 kW on tap from the batteries, far more than the heavier pack of floodies would have given you, and roughly 90-100 peak horsepower reaching the motor. This would give acceleration and top speed like the original gas powered Z car, and perhaps 40-50 miles range to full discharge. Significantly more range if you did extensive modifications for efficiency(LRR tires, aeromods, synthetic transmission oil, ect.).

    But also understand these batteries I’m talking about are batteries I have no experience with, and the number of people using them in conversions are by no means numerous. The two people I know of using them have had no problems so far.

    Just throwing ideas out.

  32. — Joe    Jun 20, 2006 10:44 AM    #

    John, thanks for your ideas, you seem very knowledgeable with EV’S. Were probably going to go with some sort of kit since this is out 1st EV conversion and we would not know where to find all of the EV parts that you mentioned and trying to piece everything together (unless you were in our area) or we had your knowledge, we wouldn’t attempt it. Also the AGM’s may be good but I don’t think we want to deal with regulators and all the other mods to deal with that. If we left with the ICE config then mods would be no problem for us, but kinda boring, the 280Z-EV sounds more exciting. Were looking for 70+ range & 0-60 in maybe 10 seconds? If thats possible, and yes we may go to 192V. Thanks again for all your suggestions.

  33. — John Westlund    Jun 20, 2006 14:52 PM    #

    You’d need AGMs to do 0-60 mph in 10 seconds using lead acid batteries. Flooded lead acid batteries just don’t have the power.

    With a good set of floodeds and properly selected components, you may be able to eek out a 16-20 second 0-60 time with flooded batteries. But they just don’t give you much power.

    70+ miles range is doable. But you will need at least 1,300 pounds of lead on board to do it, assuming it’s at highway speeds. Might make the car weigh more than you like. If you did extensive aerodynamic and other efficiency modifications, you could get that 70 miles range on far fewer batteries. But you might significantly alter the car’s appearance.(ie. rear wheel skirts, custom rear spoiler for reduced turbulence, lowered ride height, ect.)

  34. Joe    Jun 21, 2006 22:08 PM    #

    Our current plan is 12-14 Trojan J150’s (approx. 1000-1175 lbs. of lead) lighweight bumpers, fenders & hood. I guess well have to settle with whatever 0-60 time we get and now hope for a 60+ mile range.
    This Z has a 3.55 gear ratio & this will be a DC kit with the existing 5 speed trans.

  35. — Charles    Jan 16, 2007 01:45 AM    #

    I noticed that you strongly recommended against walmart batteries but dr larry used them very successfully. is this because of his unique charging setup?

  36. jerry Halstead    Jan 16, 2007 12:21 PM    #

    Hi Charles,

    Without know how he is using the batteries (range, depth of discharge, current draw, cycles, etc..) I can’t really speak to how well they are working out for him in comparison to my experience with similar batteries. If I remember correctly he lives in a warm, relatively flat part of the country while we have steep hills (heavy current draws) with sub-zero temps for part of the year.

    You are right though, I suspect his charging setup makes a significant difference in the health of the batteries. I’ve always thought a single charger pumping current into a dozen batteries in series is a brute force means of charging, even more so during an “equalization” charge.

    If someone had the time and money it would be a great project to do a bench test comparison between different styles of batteries and charging methods. For example, how much extra life could you get out of a pack of good trojan deep cycles as compared to the w*lmart brand, if you used the same charging setup?

  37. — Matt Gossett    Feb 05, 2007 13:28 PM    #

    I am interested in converting my 1922 Model T Ford Roadster to electric. This would be my first conversion. I only need a range of 30 miles with a top speed of 50-55 mph. Without the IC engine, the Model T weights less than 1,000lbs. The wheels are very narrow which should help. I like the idea of using AGM batteries. Any suggestions on motor size and battery pack?

  38. — James May    Feb 10, 2007 13:33 PM    #

    Hi Matt,

    I guess nobody has answered you yet because we don’t want our advice to spoil your rare car.

    Anyway, here’s some non-committal stuff:

    I don’t think your requirements are very demanding, you could put together a lead acid pack which would provide this sort of power and range relatively inexpensively, maybe if you can afford it, you could go for a small lithium ion pack, they’ll last much longer than the lead acids. More expensive getting a suitable charging system though. What I would do is look at all the similar cars on evalbum and see what they have done. This is what I do when I want ideas.

    Also check out the ev calculator on this site under EV tools.

  39. jeff    Feb 22, 2007 05:57 AM    #


    I’m finally gunna take the plunge and build an EV from one of my Vdubs. Question is motor size?
    I realise you have used a 9” in your first conversion… I’ve been wondering about these E-tech motors. They run on 48v but only produce about 8-12hp. Given the Vdub’s transaxle will still be used is there a method to determine a good hp rating from a DC motor for suitability?

    BTW, I’m having a blast reading through your trials from the first one – the Mazda. Haven’t read all the pages yet – it’s nearly 4am now :(

    As for the sextuplets problem with battery cells… In a previous life I used to work with industrial chargers for electric fork lifts. Battery cell failure can result from plate bridging from sponge-lead falling to the bottom of the cell (service-able), plate sulfation (fatal) and more (run into negative).
    Often an errant cell can be resucitated(sp?) but it involves discharge testing and being able to isolate the questionable cell which is tough in an enclosed “maintenance free” type of battery. Essentially, the process is to discharge the battery at a given rate suited to that battery’s output or Ahr rating and measure each cell’s voltage at regular intervals (say 60min, 30min, 15min etc). At some point, your “bad kid” cell would drop below 1.5v and then would need to be jumped-out of the circuit (short circuited across it’s + and – poles) allowing the rest of the cells to be discharged. This requires being able to modify the load to account for the lost 2vdc cell. When the rest of the “kids” reach their dicharged state, the jumper across the bad kid is lifted and the whole battery is low-rate charged back-up. Then an acid check is done (always at peak charged state) to see if the bad boy in the bunch is needing adjustment and the whole process is repeated (discharge test). After repeated cycles it should come back or at least identify it’s limits (ie: “this” battery is a 4hr battery instead of it’s rated 6hr.
    Whew. Maybe shoulda saved this for another post… Sorry ‘bout that chief.

  40. — James May    Feb 22, 2007 08:40 AM    #

    Hi Jeff


    If you can’t jump-out the “bad kid” in a monobloc can you do a general trickle charge and overcharge the other cells until the “bad kid” comes up again. I ask because only of my 6V Golf cart monoblocs sometimes flattens before the others and I suspect jsut one cell. The whole monobloc has momentarily reversed under load I think.

    Anywaym I am repeatedly running the final phase of my charger after a discharge (at just over 2.4V/cell) to try and equalise the pack. It seems to be getting better.

    I have a voltmeter on each monobloc now so I can see how each monobloc of 3 cells behaves under load.

  41. — Flopstall    May 31, 2007 10:21 AM    #

    Has anyone done a conversion on a 1991 or 1992 Acura Integra (Honda 1.8L ICE)? If not, can you say “It’s just like converting a xxxxx”? Thanks.

  42. — James May    Jun 01, 2007 07:17 AM    #

    EV Album? There are some Civics and Accords here.

  43. — Jim Taylor    Jun 13, 2007 20:41 PM    #

    Obviously Li-Ion batteries are going to be the future—when they come down in price. Has anyone pondered using a small bank of Li-Ion batteries for quick-charging and more volts “on top” of the traditional set of 6 volters.?

  44. — Randy Scott    Aug 01, 2007 21:37 PM    #

    Matt Gossett;
    My friends in the Houston Elec Auto Assoc tell me that they have seen a Model T converted to EV and don’t recommend it.
    They say the suspension & steering won’t handle it and it turns out to be dangerous to drive – too much weight & torque. Put that baby in a museum and start with street rod parts from companies like Total Performance or Spirit Industries that are designed to carry the weight and handle the torque of a blown V8.
    That’s what I want to do, in fact I’m doing CAD layouts and think I can weld up a frame to hold about 18 to 20 batts with a turtledeck.

  45. — John G    Aug 05, 2007 14:29 PM    #

    Jerry et al,

    Li-Ion cells are CURRENT technology, almost avaialble in the power densities we need (thanks to Texaco they are not).

    The NEW technology is carbon nano-tube cells (Ultra Capacitors as they are known). When these are marketable, and they are close (so if no big oil company buys out the patent and buries it) we will have EVs all over the place.

    Imagine: Silent, non-polluting cars that have ranges of OVER 200 miles/charge and use off-peak power for charging and expected useful lives of 20+ years!

    It’s closer than we think.

  46. — Dr.Larry    Aug 12, 2007 17:38 PM    #

    How much do you think they will cost at first

  47. — Brian    Aug 29, 2007 23:05 PM    #

    I’m just starting out my research on doing a conversion. I see lots of comments on Li-Ion, batteries being the future. Why Li-Ion over NiMH? I know Li-Ion is about 50% more powerful, but the lifespan on Li-Ion is only about 3 years from born-on-date. NiMH have been used for over 200,000 mi in some EVs. That’s like 10 years driving!

  48. — John Jackson    Aug 30, 2007 00:38 AM    #

    There are a variety of flavors of Lithium batteries out right now. The one that seems most promising is the A123 nano-phosphate version. I regularly severely abuse a couple of the Dewalt battery packs(which use the A123 cells) that I use to run my electric bicycle and they keep running strong. A123 is working with a variety of companies in the auto and transportation industry to develop a good long term pack for hybrids and EVs. They have recently developed a couple of new cells specifically for the higher outputs needed for those vehicles. As you mentioned, weight is a great factor in the choice of a battery. If I can choose a chemistry that cuts my battery pack weight in half for the same range at only a reasonable markup in price, I will do so.

    That said, watch the Firefly lead acid carbon graphite technology. While not as robust as the lithiums, it may prove to be a worthwhile investment as they claim the same level of power output in a package half the size of a standard lead acid. And they say that while there will be a premium price, that it will still be more reasonable than the lithiums. I’m having fun watching the new technology race for the green flag.

  49. David Pino    Mar 18, 2008 17:51 PM    #

    I have just come into about 1,000-1500 12V, 4.5AH NiMH battery packs.I have been dying to make an EV for about a year now. This may be the push I needed to get me going. Of course these are used cells, but hey, thats a lot of free cells. The delema at hand is. How do you test all these things effectively. Do I string’em up to about 400AH and use a 12V Battery charger pushing 50 AMPS and see what happens? I’d hate to damage these things because I could probably get a descent energy system from them. Any Ideas?


  50. Greg Fordyce    Mar 20, 2008 05:33 AM    #

    I read somewhere that NiMH don’t parallel very well. You will probably need to design a battery management system of some sort. Try posting your question on the EVDL. Someone there might point you in the right direction. It will probably be a lot of work getting them connected in a safe way but you already have one of the most expensive parts of a conversion, the batteries. Good Luck,


  51. Abhinav Duggal    Mar 23, 2008 02:53 AM    #

    Hey all this is my first post. I have developed a hybrid vehicle earlier, now I want to convert my car to electric car using Zebra Batteries but I have heard that these batteries are high temperature batteries (270 C), Is this correct . If yes? Could anybody tell me how this can be implemented in the cars?

  52. Greg Fordyce    Mar 25, 2008 05:42 AM    #

    Hi Abhinav,

    They do operate at a high tempurature, the best place to start is with the manufacture of the batteries, you need to make sure that they are availible for a one off project and at what cost.


  53. Abhinav Duggal    Mar 25, 2008 13:44 PM    #

    Could you tell me what is C/20 rate actually means? Does it mean that if a battery with 100 AH capacity @ C/20 and 200V give us 200*100 Wh or 20kWh of energy?

  54. Abhinav Duggal    Mar 25, 2008 14:14 PM    #

    Hey could anyone tell me that if the tool available on this for sizing the batteries is correct to what extent. But from my information this tool does not make use of ACCELERATION criteria, which is very important.

  55. — James May    Mar 25, 2008 14:59 PM    #

    Hi Abhinav

    C/20 rate refers the current rate of drain at which the battery holds 100Ah.
    C/20 means 100/20 or 5A. You’d expect the effective Ah rating of the battery to be lower if you pull a higher current from it. There is an equation for it. Maybe search for Peukert’s exponent value for your chosen battery. The higher this value is above 1, the more more the level of current drain will affect the effective capacity.

  56. Joe    Apr 04, 2008 13:22 PM    #

    These batteries could be the ticket: http://www.autobloggreen.com/2007/12/11/toshibas-new-scib-battery-charges-in-5-minutes-releases-march/

  57. — D    May 19, 2008 10:14 AM    #

    Hello EVerybody!
    I plan on converting a common 3 wheel trike and instead of the vw engine and transaxle I would like to run a 9 inch motor with no tranny.
    Is it possible with 16 × 6v trojan T-105 = 96 volts and total weight inc. batteries at 1542lbs (700kg) that I could reach 60mph and get 80mile range? or would I need to run at least 2 forward gears?

  58. — James May    May 19, 2008 17:52 PM    #

    Hi D

    What you are thinking of doing sounds difficult IMO. I think you might not get very good acceleration if you are geared to do 60MPH. Hills could be trouble.

    The 16 6V T105s are similar to my 16 × 6V Trojan T6220s I had in my car. It weighed around 1.2 tonnes but definitely needed 3 gears.

    The problem with your idea as I see it is that you’ll be relying on lots of torque, i.e. lots of current and those Trojans have quite a high internal resistance. You’ll get a lot of voltage sag, a reduced range and quite a short battery life.

    Anyone else want to weigh in on this?

    It’s always worth looking on EVAlbum to see what other people have done.

  59. Kev    Jun 03, 2008 00:56 AM    #

    I am also thinking of building a trike from the ground up. A reverse trike using a mustang II street rod front end. I was hoping to not have a tranny but the previous comment gave me pause. I was eyeing the UB121100s. This would be only 840lbs (x12). Is this still to hefty to go gearless?

  60. — Glenn    Jun 03, 2008 19:34 PM    #

    Has anyone used wheelchair batteries on a EV? If so what are the pros and cons compare to deep cycle batteries?
    I have some basic info from power sonic batteries its a Sealed lead Acid Battery 12v 55.0 AH? what does this mean
    20-hr. (2.75A to 10.50 volts)….. 55.0 AH

  61. — Joel    Jun 05, 2008 16:11 PM    #

    That means that, that battery will provide you with 55 Amperes total if you drain the battery’s total capacity in a 20 hr period, and as stated, you would need to draw 2.75 Amps for that ammount of time and eventually the batery will drain to depletion which would be a total of 10.5V instead of the 12V+ when charged. I’m no rocket scientist i could be wrongbut it goes somethign like that. unless you are planning on using a really high voltage, those batteries wouldn’t work very well I think, since that batteries for EV roam arround 100-200Ahr

  62. — Cameron    Jun 06, 2008 00:42 AM    #

    What if, what if, what if! What if we were to mix what kind of batteries we used. Flooded lead acid where we could reach them comfortably to check them, and AGM with regulators in locations where we couldn’t? Would this cause our system to be out of balance? Would eveything keep working? Would the world continue to spin the same direction?

  63. — joel    Jun 06, 2008 17:29 PM    #

    well some batteries have higuer resistance than others so some would discharge faster and run the risk of reverse polarity & Battery damage. Sone last longer than otters in life time, and some accept more abuse. just slide with using the same batteries

  64. — Chris    Jul 22, 2008 16:01 PM    #

    Has anyone checked out the Batcaps? I’m thinking of using the Batcap 800. They discharge and charge as fast as capacitors which will help in many ways. Also they only weigh 14 lbs each. For a 144V pack the total weight will be 168 lbs! That’s way less than the other batteries I seen mentioned. The life span of these things is 3-6 years and they don’t require maintenance. At http://www.batcap.net/800.html they sell for $179.00, while on ebay they sell for 139.99 w/ free shipping http://www.caraudiodeals.com/xstatic-batcap-800-stereo-battery-800-cca-free-shipping-p-84.html

    The 800 stands for 800 amps. Batcap 800 is a 12v capacitor/battery used mostly for power hungry car audio systems. I think that these could work for EV’s because there light, maintenance free, long life span, fast recharge and discharge, and not to mention price. I’d like to hear some thoughts about this. It sounds like it would work great in an EV. I’m trying to build an EV after coming across this site and I have a list already of what I need. I’m planning on using a Zilla 1k with a 9” motor. Looked at the driveshaft adaptor that mounts to the motor. It’s pretty cool that you don’t have to have a transmission if you don’t want to, but I think it’s better to keep it. Guess I’ll just read the next pages now and check back for a response later.


  65. — Eric    Jul 22, 2008 16:09 PM    #

    They aren’t deep-cycles, the 800 is peak not amp hours. The 800 doesn’t have amp hours listed but the 2000 has only 50 amp hours. and it’s listed at 1500 cycles at only 30%.

  66. — Mike    Sep 28, 2008 13:58 PM    #

    On my 48 volt Columbia golf cart I have an auto fill system to fill my 8 6 volt batteries.I put one end of the siphon hose in a gallon of distilled water and the other end connects to the batteries via tubes with special filler caps. All I have to do is squeeze the bulb siphon until I can’t squeeze the bulb anymore and all batteries are the properly filled.The whole process takes maybe 5 minutes and is neat and easy.With this system you could locate batteries in previously unusable areas.I think you can buy these systems from golf cart part suppliers. see http://janwp.com/mm5/merchant.mvc?Screen=CTGY&Store_Code=JANWP&Category_Code=BWS_GOLF

  67. — EVdude    Sep 28, 2008 16:10 PM    #

    the batcap 800 is rated at peak output. this would be good for a drag racing ev. have you seen the batcap 8400. use 29 of these batteries with a twin motor design like john wayland put in his white zombie ( www.plasmaboyracing.com) and one zilla 2k EHV controller per motor and you have one fast drag racing ev that could push the lower 10 seconds or even the upper 9 seconds for 1/4 mile. i wish i had that kind of money.

  68. — Dan P.    Sep 29, 2008 00:58 AM    #

    All customers should read this important information:



  69. Jerry    Sep 29, 2008 07:36 AM    #

    Very sad. Hopefully an equally capable and talented person picks up the license.

  70. — James May    Sep 29, 2008 08:03 AM    #

    I’m glad I bought my Zilla controller when I did. I think Otmar has signifigantly raised the bar for DC controllers with the Zilla. The EV community is better for it. Thanks Otmar! I hope things are going well for you!

  71. — Evdude    Sep 29, 2008 21:27 PM    #

    I can’t believe that they are no longer manufacturing the zilla controllers. and i was planning on buying one for my second EV. I hope someone competent picks up the license so i can.

  72. — Dan P.    Sep 30, 2008 02:04 AM    #

    Sorry Jerry,

    I probably should have looked for a controller category to post that info back when I had read about it a week ago or email it to you so you could post but then I got busy.

    When I read Evdude’s comment about wanting a Zilla 2K – I said to my self… @#!*#%^& I knew I was forgetting something; I’ll be 45 this Thanksgiving and my short term memory is already leaving me.

  73. myazel    Oct 02, 2008 14:13 PM    #

    I am looking at converting one of the Japanese Mini trucks that coming into the country used. Weight is about 1500 pounds now. Current ICE 660cc/40 HP. Any suggestions on motor and batteries? I would like a 50 mile range at 50 MPH if possible. Thanks!

  74. Said    Oct 03, 2008 11:20 AM    #

    I am also thinging of converting older japanese trucks (diahtsu wide 55) or otherwise a Renault Gordini/dauphine. Looking to get 50 mph and 50 mile range with a 72 volt system. Maybe this is only possible with the small renault. Any advice?

  75. — Greg Fordyce    Oct 03, 2008 19:55 PM    #

    Have a look at my small Fiat 126


  76. — James May    Oct 05, 2008 17:31 PM    #

    Hi Greg

    It’s great to see your Fiat 126 finished. I was wondering about how it was getting on. My Nightfire Special is pretty much finished as well. It only really needs a charger and a DC-DC converter.

    I have a UK reated question. Have any insurance companies asked you for an engineer’s report?
    I have been asked to provide one for one insurance company and I am not sure:
    a. If I need one.
    b. How I would go about getting one.
    c. What they are looking for.

  77. — Dan P.    Oct 06, 2008 05:34 AM    #

    Hey James and others,

    I had once came across someone’s conversion here on the internet were a guys town required such documentation.

    He showed in great detail including formulas for “G” forces that his battery boxes could withstand tremendous lateral sheering and impact which surpassed OEM design crash tests; I even recall him stating in the pdf what type of grade nuts & bolts that were used.

    Wish I could find it for you right now but I’ll have to look on one of my other computers to see if I still have the link.

  78. Kyle B    Dec 27, 2008 10:24 AM    #

    AGM Batteries – I have ruined my Universal Battery UB121100 after only 7 weeks of use. A couple things I should have known before I used them (I focused on price and amp-hours):

    0% state of charge is defined as the depth of discharge giving a terminal voltage of 10.50 Volts – measured under a steady load at the 20-hour rate at 80ºF. (The 20-hour rate is the 20-hour capacity divided by 20 hours.) *** No-load SOC for AGM: 100%=12.8 , 0%=11.8 ***.

    And from Lee A. Hart:
    “With cold AGMs, you will find you can drive normally until they get below about 50% SOC. Below that, the voltage starts to sag badly. If you take them down to 20% SOC or so, you will find that even modest currents cause them to sag to 1v/cell or worse! (6v from a 12v battery)! Stop driving or you will murder them.”