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Re: (ET) Ni-Zn batteries



Harry:

I bought some Evercel MB80's and tried them in my 1985 VW Cabriolet. I documented some of what I did at:

http://pw1.netcom.com/~fw/index.html

These batteries produce a TREMENDOUS amount of heat on both charge and discharge. I eventually had a battery fire which began 1 hour after I took the batteries off charge. this wiped out the rear battery box in my car. Alas, i didn't have the cooling system I had painstakingly built running, nor the temp sensors I had all over the battery pack.

I guess my reaction today would be that this is an interesting battery chemistry, but you need to go into it with eyes wide open. You most certainly don't want to just put these batteries on a lead acid charger or just draw whatever current you want out of them.

I will try to look back for other notes on charging algorithms if that would be helpful.

FW

harry landis wrote:
Well, I went back today and looked at them again. They are indeed Evercells, and from the dust on them, it looks like they have been sitting around for four years. There are around 36 or so of them, although there may be more available. I was told they were never used, because there was a problem with the charger. Maybe that's why Evercell went broke. They are all discharged. Most of them are double batteries, made up of two of the one shown in these photos, stuck together side by side to make up 24V 40AH. It sounds like they can be had for around $25 ea. I'm not sure if that's per single or per double battery. I got a couple of them to mess with. But I will be leaving in a couple of days for 6 weeks, so I won't have any answers before I get back. But the owner would like to unload them soon if possible, so if anyone is serious about getting a good portion of them, let me know and I will put you in touch. He probably won't be interested in selling just one or two.
Photos here:
http://members.alcisp.com/hlandis alcisp com/niznbat1.JPG
http://members.alcisp.com/hlandis alcisp com/niznbat2.JPG
http://members.alcisp.com/hlandis alcisp com/niznbat3.JPG
Harry Landis

> From: etpost drmm net
> To: elec-trak cosmos phy tufts edu
> Date: Sat, 12 Jan 2008 03:35:37 -0500
> Subject: Re: (ET) Ni-Zn batteries
>
> Some years back, a company by the name of Evercel introduced nickel-zinc
> marine batteries. The batteries themselves were manufactured in China.
> Cycle life was rated as 500, IIRC, so somewhat less than lead golf car
> batteries, which run around 750-850 cycles with good care.
>
> I heard of a couple of people who tried Evercels in their road EVs. This
> would have been in the early 2000s. A fellow by the name of John Pullen
> built a Honda Accord (I think) conversion using Evercels and a relatively
> high voltage AC drive (264 volts).
>
> Here's his very positive initial description of the batteries :
>
> http://www.crest.org/discussion/ev/200202/msg00093.html
>
> Last I heard the car was out of service, but I don't know why.
>
> Leo Galcher used 11 Evercel batteries in a BMW conversion. He was initially > pleased with the range and performance but he had a large number of battery
> failures and eventually gave up on them. I suspect a good part of the
> trouble he had was caused by the much higher current his lower voltage DC > drive required. Evercels had (and I think NiZn in general have) relatively > high internal resistance and they're not happy with high currents. However,
> an ET is a much more modest load than a road EV, and might make them
> happier.
>
> Evercel went out of business about 4 years ago. I did hear that some folks > scrounged a quantity of discarded batteries from the loading dock behind the > Evercel shop after it closed down. If you've found some of that old stock, > or other, it would be hard to tell how useful it might be this far down the
> road (but in theory nickel-based batteries don't die from being left
> uncharged as lead batteries do).
>
> Whatever kind they are, make sure you have some source of support or
> information, because from what I understand NiZn use a different charge
> profile from lead batteries. A little nosing around in my archives turned > up this vague reference : "I believe they indicate a ~22amp constant current > charge to 16volts, followed by a 4amp finishing charge, (dunno termination > on this)." Someone else countered with "Less than 58 amps and never exceed > 14.2 volts is what I am using." Evercel made some batteries with 7 cells > and others with 8 cells, and with different capacities, so that might be the
> source of the confusion.
>
> In general, using something unusual like this is not for the faint of heart.
> But if you got them cheap enough, you could probably afford to let the
> smoke out of a few until you figured out how to do it right. (Seems to me
> the original price was something over $200 each.)
>
> In any case, I don't think the ET charger could be used stock. Most likely
> it would destroy them in a few cycles.
>
> Hope this helps.
>
>
>
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