Re: (ET) Ni-Zn batteries

["David Roden (Akron OH USA)" <etpost drmm net>]

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.