No problem, Mike. I'm not questioning your experience, just that I found some other blogs
where they didn't have the same results. I googled parallel/different capacity/old/new/
charging/deep cycle/etc./etc., and came up with several discussion threads with some
(may have been marine applications) different results and opinions, that's all.
I've been running a hypothetical scenario in my head, and still can't figure out why electrical
energy would try to travel from a fully charged battery at rest, to another fully charged battery
at rest, no matter what their respective ages or conditions are. Fully charged is fully charged.
Like, Battery A is new, and can hold a finite amount of charge, let's say 160 amps, and Battery B is
3 years old, and now can only hold 100 amps. If both batteries are at full charge capacity,
there's no place for energy to go between them, because they're already both full.
If there was a draw (or phantom) on the pair, I would expect the discharge rate would be
balanced over both batteries with the lower capacity one draining first, because it holds less.
Do you see where I'm coming from with this?
I've got a technical question in to a local battery specialty store, to see what their thoughts are.
I thought I'd ask because in all the times people have purchased batteries (me too) I've never
been warned not to use a new and an old deep cycle battery together. I would think if it were
an issue, it would be a standard warning, especially for the really big rigs that have more than 2
deep cycle house batteries.
I'll post up the answer, when they get around to me. I asked for a techy explanation in
simple terms, if they can explain it.