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Discussion Starter #1
Re: [EVDL] Battery Revival

I haven't had anything to say for a couple of years now, but I always enjoy reading the experiences and insights of the people who made it possible for me to build and drive EV's.
I had the experience last year of reviving a totally dead 72v pack in a 4 passenger GEM that my "87 year old teenage" friend Brad had bought for $500. The charger had failed, so the owner just left it parked on his chicken ranch outside Petaluma for a couple of years; he was convinced that it was going to cost more than it was worth to get it going again. I told Brad to get it to me, and I would see what I could do. I mixed EDTA in distilled water, used 2 Tbsp per cell, then started charging the batteries individually with 75 watt PV panels. Once they got to a reasonable voltage, I used 12v chargers to bring them up as well as they would. When I pulled out the dash to get to the charger, I found it was a Zivan NG1; plugging it in gave me the error codes, calling Zivan in Sacramento told me what to do (disconnect the thermal sensor), and we had a working EV. I first drove it at a good speed around my pasture, (which was a VERY rough ride) to shake up the batteries and put a l!
oad on them, then charged again. I did that 4 times, then took it out on the road, and drove it up and down until the low battery alarm came on. After I did that 3 times, I drove it up the very steep hill into a housing development toward town, again, driving it until the low battery alarm came on, then easing it back home to charge again. After that, I started driving it to work, which is some climbing, and lots of stop and go. The batteries had enough capacity for me to drive 6-8 miles before the alarm sounded. Obviously, that is not enough range for any normal EV, but it worked well enough for me to demonstrate that the GEM was a good serviceable EV, and well worth putting a fresh pack into (which I did).
The batteries I took out are still powering my RV (with a PV assist) and my on-the-farm golf cart (which needed batteries.
The EDTA treatment may need to be repeated, but for the cost, it was effective in this case.
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Discussion Starter #2
Re: [EVDL] Battery Revival

On 11 Feb 2011 at 22:33, [email protected] wrote:

> I mixed EDTA in distilled water ... started charging the batteries
> individually ... I drove it ... then charged again ... 4 times ... then
> 3 times ... After that, I started driving it to work ... The batteries
> had enough capacity for me to drive 6-8 miles ...

This is an old Home Power trick. As I understand it, the EDTA is supposed
to bind to the lead sulfate. It can't turn it back into elemental lead and
restore it to the active material in the grids, however.

Next time it might be interesting to try an experiment. Try the charging
regimen you describe without adding the EDTA on half the batteries. Use
EDTA on the other half.

My guess is that most of the benefit from this system results from the
charging and repeated cycling. "Exercising" a battery will always increase
its capacity, even when it's just about ruined (as yours were).

David Roden - Akron, Ohio, USA
EVDL Administrator

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Discussion Starter #3
Re: [EVDL] Battery Revival

> My guess is that most of the benefit from this system results from
> the charging and repeated cycling. "Exercising" a battery will
> always increase its capacity, even when it's just about ruined (as
> yours were).

That was my thought, too. Kinda like "rock soup" for batteries.

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