William Chops Westfield wrote:

> On Aug 28, 2005, at 1:49 AM, Stef Mientki wrote:
>
>> I think all NiMh chargers, sold at this moment are dV/dT chargers.
>> So that's my second question, why do you think dV/dT is unreliable...
>
>
> I think I can see where he is coming from.  I have a supposedly smart
> NiCd/NiMH charger (this one:
>   http://www.aspencer1.com/showitem.asp?ItemID=11387.43
> not really high-end, but ought to be relatively intelligent.)
> It's only so-so at detecting end-of-charge on the cells I normally
> use with it :-(  While dV/dT might be usable in theory, it looks
> like in practice the values you're looking for can vary quite a bit,
> depending on battery make, age, initial charge state, and so on.
>
well I was talking about something havier, full charge in 10 .. 15 
minutes !!
About 12 years ago, I build a charger with the ICS1700 or ICS1702.
I then did tests with about 50 NiCd batteries, from all kind of brands.
Most of the batteries (about 40) where totally broke,
capacity was measured before through a normal charger,
and capacity varied from 0% to 80%.
After a few chargers with my charger,
almost all batteries had capacities varying from 110 .. 130% !!!
I also logged the battery voltage (amplified) on a paperwriter (if 
that's called so),
and I can assure you that the dV/dT detection is perfect.

But the great trick is when to measure the dV/dT.
The factory that produced the ICS-1700 had patent on that,
check the datasheets !

Now twelve years later, I still use the charger,
and at least half the batteries still are in good condition,
after being used for 12 years !!

Stef




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