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Discussion Starter #1
Just under a year ago, I decided I was going to build an electric car.

Well, guess what, now I have one.

I converted a '96 Geo Metro to all battery-electric with a used forklift motor and batteries.









Works pretty well for running errands around town and going to and from work.

The whole project if extensively documented on Ecomodder.com, but I wanted to get some information about it out here as well.

Take a look at the specs in the garage.

I have a number of videos on YouTube about building the car.

Here's the latest one: http://www.youtube.com/watch?v=sZS3bbEPshY

I even put together a "structable" on the car for Instructables.com

Please, let me know what you think of the project.

Thanks,

-Ben Nelson
 

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Wow! Good job Ben...I'm amazed that the body is in such good shape for a $500 car. Good luck with it.
Roy
 

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Discussion Starter #5
Hey guys,

It's time for an upgrade to the car. My controller is a 48-72V and I already have 6 batteries, so I am maxed out there.

I think the next step is add an additional parallel 6 batteries as "buddy-pairs" to keep the system voltage the same, but double my capacity. If I can ever get my hands on an affordable 144V controller and charger (or just a second 72V charger) I could easily upgrade to 144V later.

I know I will have to upgrade the suspension. I did do a rolling test a while back by setting 6 more batts in the back seat. Suspension was harsh, but the brakes were great, no problems there. That's also right at my GVW, so 12 of these 12V lead blocks is my absolute maximum.

I would like to sink battery boxes down into the frame (er, unibody) of the car. I would do 4 batteries where they are, but lower, in the hatch/spare tire well are. I would sink 4 more straight down in the back seat as that's where the gas tank originally was. And I should be able to fit 4 total batteries under the hood.

Does anyone have suggestions for me about the best way to build battery boxes sunk into the frame? I have limited welding experience, but have plenty of new EV friends who can help me with that.

I also want to make sure to keep the structural integrity of the car. I think that I want to make the "holes" as small as possible. Four of my batteries in a row take up a space of 13" by 28". That easily fits in the footprint of the back seat without cutting into any structural metal folds.

I am imagining cutting a hole in the car with a plasma cutter and then dropping in a pre-built battery box which would have and angle iron lip that would stick out and catch on the the existing metal. In the rear side, that would catch directly on the cross support that the seat belt bolts went into. and I am sure I could extend it just enough to catch, on the front, the structural section of the car body where the metal bends down to form the vertical part at the front of the back seat.

Here is a photo of the back of my car with the existing 4 rear batteries, and the back seat removed.


You can see right in front of the batteries is a structural cross member that I am sure I would want the battery box to mount to.

It's been some time since I removed that gas tank on this car, but I would think that the bolt holes to attach the gas tank could be reused as attachment points for batteries as well. (Not all by themselves of course!)

Any hints or tips on building a box down into the car? Please let me know!

Thanks,

-Ben
 

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Does anyone have suggestions for me about the best way to build battery boxes sunk into the frame?
I am *almost* done with a 1997 suzuki swift (geo metro). I sunk a rack under the rear seat... There is room for 6. I am using us8vgchcx, which may be slightly different size than your batteries. You have to be careful of the brake lines when cutting. You don't need plasma... just start the cuts by plunging a 4" angle grinder at the corners, and use a sawzall with metal blade.

I have a ton of pix on my site www.envirokarma.org/ev for design ideas.... I used 1x1 steel angle rails, and lined with 1/4" polypro plastic.
 

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Discussion Starter #7
Thanks Dan,

Your web site is great!

That's exactly the kind of info I am looking for!!!

My 12V batteries are a little longer than yours, so I wouldn't be able to fit those two "turned" batteries in there.

Your photos help a lot. Looking at those makes me realize I will have to watch where the parking brake cables go too!
 

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I did a very similar design but used a handheld jigsaw for most of the straight cutting.. the upper frame for my rear box has 2x2 angle iron outward to sit over rear frame rails and bolt down. I takes all the space between the rear frame rails side to side and from the suspension crossmember to the rear of trunk wall front to back. My back seat was too low to really use the space where the gas tank used to be (without losing my rear seating - then my daughter would have to ride in the trunk!)

I used aluminum for the rear box and a treated plywood box for rigidity.
 

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My 12V batteries are a little longer than yours, so I wouldn't be able to fit those two "turned" batteries in there.
I think you can.... There are a couple more inches I COULD have gone wider on the rear-most ones (but not the front 4). It is a very close fit between the seat lip, and the rear wheel suspension with my batteries....

I think that is the orientation used for the pre-fab battery tray sold by the guys at CanEV.com . I would have considered pre-fab except for the expense and that my 8v batteries are considerably taller than 12v batteries and I wanted to retain headroom for the rear seat.

In my case I made the top of the rack level with the seat lip, and still have about 6.5" clearance between the bottom and the ground.
 

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Discussion Starter #11
Also, since I was tearing everything out, I took out the passenger seat.
I am starting to appreciate how easy everything is to work on in a Metro. I just pulled out 5 bolts, all with the same head size (12mm, same as EVERYTHING on this car) and the seat pops right out!



With all that additional space, there isn't a whole lot stopping me from just setting more batteries right in there!

I also tried the TURBO again. On the one straight and flat stretch on the way to the bank, I hit the turbo - this time in 3rd gear to limit current.

The ammeter shot up to the 300 amp limit, but after a few seconds, started coming back down into the range of the ammeter.

The car briskly accelerated to 45 mph, and then I had to let off of it because of the speed limit there.

So, using a lower gear to limit amperage with the turbo does seem to work, but it's still pulling more amps than my batteries are really happy with. Once I get another six batteries in parallel, the amperage per battery will be half, and it shouldn't be as bad.
 

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Discussion Starter #12
I do now have two strings of 72V in parallel with each other.

The other day, I went for a 16.4 mile ride. Everything was working great. Considering that the farthest I have gone in the winter on the single string of 72V is 10 miles, it's pretty nice to go farther than that now.

The spare 6 batteries are 2 on the floor of the passenger seat (the TURBO batteries) and four more where the back seat was - strapped down to a piece of plywood.


Having batteries in parallel really seems to keep the batteries happier. Not drawing nearly as many amps.

After looking at some various photos of similar cars with sunken rear battery boxes, I think I CAN fit 6 or 7 through the back seat. My batteries are just a tad under 10 inches tall, including the posts. If I had a ten inch tall box, even with the front of the back seat, the box would stick 3 inches out the bottom of the car and clear the road by 4 inches.

How much road clearance should I aim for? I don't want a speed bump to what my battery box!

I also grabbed a big button I plan to use as my "In Emergency" disconnect button. It's just a large, plain, aluminum momentary-on button. I colored it red with a Sharpie® Marker.
 

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four inches is extremely low ground clearance. You don't want a battery box to be the lowest point on your car, imo. I personally wouldn't make them any lower than the frame rails that run under the car. If you do encounter a large speed bump or deep pothole, you want the frame rails to take the hit, not the batt boxes.
 

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After looking at some various photos of similar cars with sunken rear battery boxes, I think I CAN fit 6 or 7 through the back seat. My batteries are just a tad under 10 inches tall, including the posts. If I had a ten inch tall box, even with the front of the back seat, the box would stick 3 inches out the bottom of the car and clear the road by 4 inches.

How much road clearance should I aim for? I don't want a speed bump to what my battery box!
I think minimum legal ground clearance in my part of the world is 5 inches. Speed bumps here (built to one of the standard profiles) will be 4 inches tall. With a little bit of suspension movement coming off the bump, cars with 5 inches ground clearance can still bottom out. Cars with just 5 inches ground clearance are usually lowered vehicles with much stiffer suspension than standard. Considering how steeply some of the speed bump profiles rise at the front and how square the front of a battery box is it could dig in if it collided with a speed bump.
 

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I think minimum legal ground clearance in my part of the world is 5 inches.
Lots of humps are up to 4"... especially those short ones in parking lots. The edge of the battery box PROBABLY is close enough to the rear wheels to ride up and not high-center.

My hanging box (suzuki swift = geo metro) has about 6.5 inches clear, and I made the top flush with the rear seat edge, and have the tall 8v batteries. Check out pix on my site.
 

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Discussion Starter #16
Hey Guys,

I haven't been over on this forum for a while.

Last thing I was posting was about designing the battery box.

The battery box is great. I cut a hole in the back seat, and welded in a heavy duty sheet metal box. The bottom of the box does not stick down any father than anything else under the car. The top of the box does stick up a little farther than the original seat does. You CAN sit on the battery box cover as a back seat, but it's not padded, and you'll have to duck a bit as it is higher. Due to weight considerations, because of the batteries, I was planning on basically using it as a two-seater anyways.

Also, in the past, I have bought a couple of "How To" electric car instructional videos, and was really disappointed in what I got.

So, I made my own instructional BUILD YOUR OWN ELECTRIC CAR DVD. It actually became a two-disc set - one video DVD of me showing everything I did to build an electric car, and a DVD-ROM with 50 YouTube videos that I made while building the car, over 600 photos of the project, web links, and even the template for the Geo Metro adapter plate.

If you are interested in the DVDs, head over to my web blog:
http://300mpg.org/electric-car-instructional-dvds/
 
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