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(ET) Weird Battery Behavior
- Subject: (ET) Weird Battery Behavior
- From: thumphrey myself com
- Date: Sat, 31 May 2003 13:00:21 -0500
- Delivery-date: Sat, 31 May 2003 14:02:49 -0400
- Envelope-to: elec-trak-outgoing cosmos phy tufts edu
- Sender: owner-elec-trak cosmos phy tufts edu
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
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).
My first thought is that maybe the Trojans are worth the extra 50% over
the cost of the Exides.
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