Re: (ET) Battery evaluation

[Tim Humphrey <hump evgrin com>]

 You pretty much have it right.
 
 Do you have a voltmeter?
 
 A dead battery will start out with high current and the volts will rise
 as the current falls indicating that it is indeed charging. At some
 point (full charge) the two should pretty much stabilize.
 
 The battery staying at 5 or 6 amps probably has a shorted cell. It will
 read about 2 or a multiple of 2 volts low all the time when the charger
 is disconnected. Recycle it.
 
 A really really really dead battery may behave kind of weird. It will
 start out with a very low voltage. After connecting the charger the
 voltage will spike high, but the current will remain low, indicating a
 full charge, but it's not. Then after awhile (sometimes days) the
 voltage will start to decrease and the current will start to rise. Later
 on, the current will start to go back down and the voltage will start
 coming back up. Then it will behave like a normal dead battery (like the
 first example above). Reviving a battery like this one is a hit or miss
 as to whether it will be any good or not. It may have a very low
 capacity that gets a little better after a few cycles. Then again it may
 not. It will probably never have full capacity, but, if your lucky, it
 may be quite close.


--
Stay Charged!
Hump
"If you don't "believe" you'll make a difference, than you probably never 
will!" -- Jim Husted
 
 
> 
> 
> 
> -----Original Message-----
> From: elec-trak-bounces cosmos phy tufts edu
> [mailto:elec-trak-bounces cosmos phy tufts edu] On Behalf Of Bill
> Alburty
> Sent: Friday, January 25, 2008 12:29 PM
> To: Elec-trak Mail List
> Subject: (ET) Battery evaluation
> 
> Thanks Jim for the address explanation. Now, I can post another
> relatively dumb question:
>  I have several batteries laying around in various states of charge
> between pretty good  and maybe dead. When I connect a charger that has a
> 
> current meter on it, which, I assume shows the amount of current being
> drawn during charging, what is that telling me about the state of the
> battery's charge? It seems that if the current indicated starts out high
> 
> then goes down in a few hours to about zero, that it is accepting the
> charge and its a good battery. If it starts out near zero, I assume it
> is pretty well charged already and is a good battery. When the current
> starts out at about 5or 6  amps and stays there for days, the battery is
> 
> not charging and is probably no good. Is that a reasonable assessment? I
> 
> don't have a load tester. I'm looking for affirmation and any additional
> 
> thoughts.
> 
> Bill
> E-12
> 
> 
> 
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