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Re: (ET) newer batteries are tougher?



The 'longest time' is for the newer sets. For example, "1 to 2 Years" is the entire 18 hour cycle.
----- Original Message ----- 
From: "Jim Coate" <jbc coate org>
To: "Elec-Trak" <elec-trak cosmos phy tufts edu>
Sent: Wednesday, September 22, 2004 7:55 AM
Subject: Re: (ET) newer batteries are tougher?


It's been my impression that it is the other way around in that old batteries require more time to get charged. Of course I may be thinking of really old, versus 'middle aged'.
A brand new pack will not be at full capacity yet, so can't used all those 
KWH promised yet, so won't need a super long bulk charge, but may well 
need a fair amount of equalization for a few cycles until everything wakes 
up.
A new pack used enough to be broken in requires the longest bulk charge 
phase to replace all those available KWH, but has a short equalization 
period as the cells generally match pretty well. If  it is cycled to its 
full capacity, then would indeed require the long charge time.
A middle age pack is losing some capacity so less KWH can be used and in 
turn less KWH need to be replaced, so the bulk phase does get shorter. As 
balancing becomes more of an issue, more time is needed to equalize. I'm 
not sure if the total charging time is all that different.
On truly old packs, such as in my truck :-(, the bulk phase is rather 
short since not many KWH involved. But the equalization phase takes 
forever as I have to keep the current very low to avoid lots of heat and 
gassing but meanwhile some cells are lagging far behind and need that time 
to catch up. So although the total power involved is low, the total time 
is loooong.
I don't use the GE charger on my ET... now I'm curious if that timer is 
"calibrated" to give the longest time to new or old batteries?


Thon Basom wrote:
I've seen references a couple of times to the fact that newer batteries need
to stay on the charger for longer periods of time than older ones.  Can
someone give me a simple explanation of why?

_________
Jim Coate
1970's Elec-Trak
1992 Chevy S-10 BEV
1997 Chevy S-10 NGV
http://www.eeevee.com


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