Re: (ET) Weird Battery Behavior

["Travis" <ozsolar ipa net>]

6.42 volts for an old T-105.  Something doesn't make sense.  You didn't
happen to be charging (or recently stopped charging) the batteries at the
same time you were taking these readings?  That is the only thing I would
know of to explain it.  Perhaps the specific gravity reading of the
batteries would help to answer this.

And my opinion for the break in phase of your batteries would be to slowly
mow your entire yard but I can't justify why.  Then after a few cycles go
back to regular pace.  I can't remember where for sure I'm think it was in
some Trojan EV literature regarding the break in period of batteries.  It
said that you wouldn't see full capacity of the batteries until after at
least 5 - 10 50% DOD cycles.

Travis
Joplin, MO
E-15

----- Original Message -----
From: <thumphrey myself com>
To: <elec-trak cosmos phy tufts edu>
Sent: Saturday, May 31, 2003 1:00 PM
Subject: (ET) Weird Battery Behavior


>
> Hi Guys;
>
> Hope everyone's well!
>
> I have some strange battery measurments and was wondering if someone 
> would
want to speculate as to whats going on.
>
>
> I have a very fresh pack of Exide (Sams Club) batts in my trak. For the
first few runs I took great care to not use them much in order to properly
> initiate them. I would mow for about twent minutes then put them on 
> charge
overnight then mow 20 minutes the next day. Did this for about 5 days.
>
> The Batts were all pretty close to one another measuring around 6.29
volts.
> Actually 4 bats were 6.28 and two were 6.30. Consistently, each time they
were measured with a rest after charge.  My DVM is rated at .5% accuracy 
for
DC voltage.  So the margin of error at 6 volts is +-.03
>
> A few days ago I blew the top off on of them (thats another story). Well
anyway, I have two OLD Trojan T-105's that came with the tractor. They were
presumed dead. The P.O. told me they were dead. I put them on a automotive
charger in series when I got them home(Dec) "just because", charged them
overnight and then left them for dead.   Well anyway, my lawn needed mowing
and it is quite a trip for me to get to Sams Club to replace the blown
battery so I swapped out the better of the two Trojan's for the Exide with
the hole in it.
>
> Guess which battery blew? Yep had to disconnect all of the back pack and
pull two out to get to the one bad one.
>
> I did the same routine as before, cut for 20 mins, charge, cut 20 
> minutes,
charge. Even though I had assumed the Trojan was scrap I didn't see a need
> to reverse a cell in it. So was trying to be careful.  It consistently
maintained a charge .4 volts lower than all of the rest of the pack. This 
is
> what I had expected really.  I went out this morning to cycle my new 
> Exide
a few times before putting it into the pack. While there I took some quick
measurements of the  packs batteries.
>
> Consistent with all of the other times. Three of the Exides measure 6.29v
2 of them measure 6.31v and the Trojan measures....what????, can't
be......it is measuring 6.42 volts. This is supposed to be a used up
battery. I thought that as batteries got near their end of life they had a
hard time coming up
> to voltage, and here this one is sitting at a resting voltage higher than
the new batteries have ever been(resting).
>
> Any thoughts?
>
> My first thought is that maybe the Trojans are worth the extra 50% over
the cost of the Exides.
>
> Stay Charged!
>
> Hump
>
>
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