|
|
|
|
|||||
|
||||||
From: Bill Boles (no email)
Date: Sun Jan 01 2006 - 18:23:59 EST
I've always been told not to mix new and used batteries but I've not had a
situation like this before and I've not tried to really think it out
before. I have 4 pairs of GC batteries in one bank on one boat and 5 pairs
on another. The specific situation I'm abut to describe is actually
occurrring on a 36v golf cart but I think its answer will be equally
allpicable to the boats. I hope Arild will comment.
Because of a bad battery cable connection I have one ruined battery (fried
post) out of six batteries that are less than a year old. Even though I've
always been told not to mix new and used batteries I bought only 1 new one.
I reasoned the others were close enought to new that it would be OK.
I put in the new batteries and turned on the (smart) charger. Reading
voltage across each battery, they were all ~6.4v except the new one which
was 7.1v. A few minutes later the old guys were @ 6.6v and the new one at
7.5v. A little later the old guys were @ 6.8v and the new one at 7.9v.
Fearing overcharging the new one I said to myself, let's turn off the
charger and think about this. I seems that the internal resistance in the
new battery must be less than in the old ones. If the internal resistance of
the new battery is still less when the whole group are in use, won't that
result in the new battery contributing more than its fair share of amp-hours
and thus become more deeply discharged than its brethren?...unhealthy
situation. Will continuing to charge the set result in overcharging the new
guy?
I let them sit awhile and the resting voltage showed a .4v difference, so I
turned on the charger again and let it do its thing while I did New Years.
Having been distracted from following charging progress I looked at resting
voltage the next afternoon. Water levels were all perfect. The new guy was
now 6.38 and all the old ones 6.45-6.46 . I started the charger again and
they were all around 7v with the new guy the highest. Wat's going on?
Advice?
_______________________________________________
http://lists.samurai.com/mailman/listinfo/trawlers-and-trawlering
To unsubscribe send email to
with the word
UNSUBSCRIBE and nothing else in the subject or body of the message.
Trawlers & Trawlering and T&T are trademarks of Water World
Productions. Unauthorized use is prohibited.
|