Re: (ET) Time for a NiMH Elec-trak - Amp hours

["Tim Humphrey" <hump evgrin com>]

I may be mistaken, but I think that the temp sensor in Nickel chemistry 
batteries is there because it's the easiest,
cheapest way to tell the charger when to shut off.

What they do is assume that if the battery is heating up then it must be 
full, so they shut off the charger. That's
why you don't get very many cycles from your cordless tools batteries. 
Constantly overcharging Nickel cells shorten
their life. But a proper charge algorithm would add cost to the tools, and 
we Americans are generally penny wise and
pound foolish and would gladly pay less up front and replace the battery 
pack three times as often.

Everthing I've read, generally "sums up" that Nickel or even Lithium 
chemistries want to be left in a state of
discharge for maximum cycle life, just the opposite of lead chemistries.

-- 
Stay Charged!
Hump
"Ignorance is treatable, with a good prognosis. However, if left 
untreated, it develops into Arrogance, which is often
fatal. :-)" -- Lee Hart


>
>
> -----Original Message-----
> From: elec-trak-bounces cosmos phy tufts edu
> [mailto:elec-trak-bounces cosmos phy tufts edu] On Behalf Of John B 
> Reinhard
> Sent: Saturday, April 09, 2005 2:32 AM
> To: elec-trak cosmos phy tufts edu
> Subject: Re: (ET) Time for a NiMH Elec-trak - Amp hours
>
> Aren't our typical Trojan Golf cart batteries rated about 200 amp/hours ?
> so our packs are 36v @ 200 amp/hours ?
> Chris wants to try a pack that is 1/4 of that ?
> am I understanding this correctly ?
>
> Should be lots lighter anyway . . . if that is what you want But in the 
> case
> of a tractor, we are always talking about MORE weight over the traction
> wheels, etc.
>
> I wonder if these NMH batteries can take recharge like the Panasonic NMH
> cordless drill packs - full recharge in under an hour !
> What does that do to charge cycle life ?
> What is the charge curve ?
> All the cordless battery packs have a temperature sensor inside them - to
> prevent overheating the pack when pushing charge rate to the max.
> I think you would want same thing trying NMH batteries on Elec-Trak.
>
>
> ----- Original Message -----
> From: "RJ Kanary" <rjkanary nauticom net>
> To: "Christopher Zach" <czach computer org>; "Elec-trak list"
> <elec-trak cosmos phy tufts edu>
> Sent: Friday, April 08, 2005 8:30 PM
> Subject: Re: (ET) Time for a NiMH Elec-trak
>
>
>> BE CAREFUL !
>>
>> ----- Original Message -----
>> From: "Christopher Zach" <czach computer org>
>> To: "Elec-trak list" <elec-trak cosmos phy tufts edu>
>> Sent: Friday, April 08, 2005 8:22 PM
>> Subject: (ET) Time for a NiMH Elec-trak
>>
>>
>> > OK, this is going to be fun. I have got a 2001 Prius battery pack. 273
>> > volts by 6.5ah.
>> >
>> > Naturally that's a perfect 45ah pack at 36 volts. So I'm going to sit
>> > down and get this to work with the Elec-trak.
>> >
>> > The real reason for this is because I need to understand how to 
>> > parallel
>> > charge and discharge NiMH packs. They're not pefect but best we have.
>> >
>> > If people are interested I'll post my trials, tribulatons and stuff 
>> > like
>> > that over the summer.
>> >
>> > Chris
>> >
>> >
>> > _______________________________________________
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>> > Elec-trak cosmos phy tufts edu
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>>
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