Re: Mixing Batteries

Bob Giddings wrote:

Well, here's what I did. I charged both the new ones and the old
ones up overnight. Then I let them rest an hour while I had some
coffee and caught up on the news. Then I measured the voltage.
The new ones got to 12.65V. The old ones got to 12.55 V. The
new ones started from 12.5V. The old ones started from much
lower, 12.3V, but I didn't think that should make much difference
over a 14 hour time span. If it does, even better.

According the charge charts I consulted, 12.5 V is still 90% of
capacity. Too good to throw away, no matter how old they are.
Amazing for batteries I bought in February 2001.

Bob

Bob, am afraid this subject isn't really your strong suit. ;-)

While the voltage measurement will tell you whether the low reading battery will draw down the higher reading battery, it tells you nothing about capacity. While the chart may tell you you have 90% capacity remaining, it doesn't tell you what that capacity is. Bet you are assuming it is 90% of battery's rated capacity and that isn't the case necessarily. The older battery could be down say to 50% of capacity and the voltage reading of 90% would equal 45Ahr not 90Ahr if it was rated at 100Ahr when new.

Mickey
.

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