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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!

Boxed In · 14 October 05

Cardboard Box

Last night I brought home a bunch of scrap cardboard with the one goal in mind of making a cardboard battery mock-up so I can start experimenting with battery placement in the electric car.

Nothing is ever that easy.

“Lessee,” I mumble to myself, “What size of battery am I going to use? I know, let’s check the internet!”

Optima 31 series

Which led to hours of searching, comparing, hair-pulling, and general lack-of-carboard-making. I’d been sort of leaning towards the Dynasty DCS100L AGM battery but when I went to find information on it, like where to buy it, the results were pretty scarce. Hey, who wants to buy a battery that can’t be found?

This lead to a whole sub-search on batteries, parsing through the various incarnations of the EVList (link below). If you haven’t checked it out yet the EVList is a place that attracts discussion from all levels of EV experience, all over the world. I like to read any post from Lee Hart, but there are a whole bunch of intelligent, honest, and experienced folks posting.

The EVList has been around forever and the archives bounce from server to server like an unpopular step-child. Google seems to only find results from the EVList prior to 2003. Yahoo plays host to a more recent archive of the discussions but seems entirely unable or unwilling to put an effort into searching the list. A great resource that is almost impossible to navigate.

After a few hours of battery obsessing I came away with two choices:

  • stick with wet cell lead acid
  • use optima yellow tops (AGM lead acid)

Lead acid is tried and true and inexpensive. Optimas are about double the price, sealed (clean!), have a relatively long cycle life, a lower internal resistance, and are built for motive applications. The new Optima D31T looks ideal for Eve.

This means I need to make or buy a battery management system to keep them from overcharging. I’ll justify it as something to be amortized over this and future versions of the EV. Pretty what I’ve done with the motor and controller, which provided over eight years of service in the first EV and should do that much or more with Eve.

Optima breakout

At the end of the night I had one piece of a cardboard mocking up the length and height of an Optima with a little breathing room factored in. Being able to lay the batteries on their side means I can make one, contiguous box in the front (and back) sitting above the motor.

Fired up my little battery layout tool to experiment with placement. Looks like I ought to update the tool so batteries can be placed in different configurations (it’s currently lead-centric). Also, a few more battery icons might make things easier.

For this image I input the length and height of the battery (rather than width) and then changed how the batteries look in photoshop after the fact. It works.

Battery Layout

The top four would be in the engine compartment, the other eight under the car. The measurements are:

Battery Size: 12.8” x 9.375”
Box 1: 40” x 29”
Box 2: 27” x 20”

Tonight I’ll measure the area under Eve where the gas tank used to be and see if this configuration will work. It would be nice to be able to use the old battery boxes. I don’t have another swimming pool to make more!

Here’s some links for your viewing and dancing pleasure:

Wanna a sure-fire way to find other ev conversion and solar projects? Search for battery box in google images.

Comments 6
  1. Jay Donnaway    Oct 16, 2005 23:08 PM    #
    Great blog, Jerry! I don’t recall you using it in your EVDL tagline- I’ve been missing out on some good reading. Thanks for the comments on mine, I’ll catch up on yours and then write back.
  2. Jerry Halstead    Oct 17, 2005 11:09 AM    #
    Thanks, Jay.

    Looking forward to watching your Karmann go electric.
  3. — Ed Cochran    Nov 10, 2005 14:37 PM    #
    Why did you not place 9 batteries instead of 8?
  4. Jerry Halstead    Nov 10, 2005 14:52 PM    #
    Hi Ed,

    The EV needs 144vdc, which is 12 batteries. Actually since a fully charged 12v battery is more like 13.5vdc we are looking at 162vdc total.

    It might be interesting to run the numbers using 11 or even 10 batteries after making sure the controller, motor, and charger can perform properly at the lower voltage.

    I’d rather have FEWER batteries (less weight & cost) if possible, while still maintaining the performance and range needed for typical use.
  5. Will Smith    May 18, 2007 17:27 PM    #

    One idea I have is to find a way to retro-fit solar panels on the roof and figure out a way to use them to recharge the batteries, rather than having to find a recharge station.

  6. — James May    May 19, 2007 05:43 AM    #

    I want to do this as well, but don’t expect to get too many miles a day from solar. I calculate around 2 or 3 for me, in summer, in th UK