Charging two car batteries at the same time

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bruce-the-man@none4u.com - 10 May 2008 10:46 GMT

Someone told me to never charge two car batteries at the same time,
with the same battery charger. When I asked why, he did not know.
I've done this quite a few times and never had problems. I only have
one charger. I have several batteries I use in a cabin which has no
electricity. Before I leave for the cabin I charge all my batteries.
I just use jumper cables to go from one battery to the next. It's a 6
amp charger and I just charge 2 or 3 batteries at the same time,
overnight. Why should this be a problem? Or is this guy full of sh.t
information?

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Steve Daniels - 10 May 2008 16:38 GMT

> Someone told me to never charge two car batteries at the same time,
> with the same battery charger. When I asked why, he did not know.
[quoted text clipped - 5 lines]
> overnight. Why should this be a problem? Or is this guy full of sh.t
> information?

I can't imagine why that would be a problem. I think sailboat
people do it all the time.

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cselby@mts.net - 11 May 2008 00:31 GMT

>Someone told me to never charge two car batteries at the same time,
>with the same battery charger. When I asked why, he did not know.
[quoted text clipped - 5 lines]
>overnight. Why should this be a problem? Or is this guy full of sh.t
>information?

If one batt is lower or weaker than the other, the better batt could
get overcharged and weaker overheat. This is using a commercial
charger. Having said that, semi trucks typically use 4 batt at a time
and almost never get disconnected and are charged as a batt "pack".
Touch the sides of the batteries after a charge to see if one is
hotter that the other. If so, stop charging those 2 batt together.

P

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benteaches@gmail.com - 12 May 2008 13:47 GMT

> If one batt is lower or weaker than the other, the better batt could
> get overcharged and weaker overheat. This is using a commercial
[quoted text clipped - 4 lines]
>
> P

I do it every day as well.
With a little 6amp charger I doubt overcharge could be an issue unless
the charger is left on for several days. Besides, if there is a weak
one, it will drag them all down.
If you have a voltmeter, you can ID weak batteries, otherwise the
above method works well.
Ben

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