> To: michael.e.r...@gmail.com; ev@lists.evdl.org
> Date: Thu, 11 Sep 2014 15:39:17 +1200
> Subject: Re: [EVDL] BiPolar NiMH (was: Kawasaki Concept J 3wheel GIGACELL
> powered EV)
> From: ev@lists.evdl.org
>
> I can only talk about the "D Cell" battery of the original Prius, I have
> worked on many of those, changed many cells, tested them to see what is
> wrong, etc. I have not seen ANY lose capacity. What happens is some cells
> suffer from increased self discharge. I measure at 1.270 V, this is about
> where they are normally. Leave it charging at this voltage on a precision 4
> wire charger until the current stabilizes. A good cell has 0.01 mA leakage,
> one that causes a problem will be 5mA. Some cells are 50mA.
> When a car has been driven until the wheels stop turning the pack is
> wrecked, most of the cells are bad, many have leaked. I think this a due to
> overcharging. Any cell that gets reversed very quickly loses electrolyte,
> avoid these conditions and they have a long life, of course it it the best
> cells that are damaged by overcharging. I have one car that still has the
> original battery apart from a few cells I have changed, this was made in
> 1998. The Prius has no balancing mechanism, apart from charging the whole
> pack so that the high cells are overcharged.
>
-Thank you for adding this knowledge/info about your method,
I use Honda cells from a scrap car for some projects.
The useful capacity seems to be lower in this model, about 4.5Ah,
charging eff. seems ok if i dont "top" them of with
a overcharge and heat them at every cycle.
They are good powercells.
But therefore not so high Wh/kg
Very stiff until they go below this 4-4.5Ah level in discharge,
I also limit them to "only" about 120 amp discharges.
probably they are about 5.5 Ah capacity if I max
them out at lower rates, but as you say, I guess
that is a very bad idea with this type of chemistry.
/John
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