Originally Posted by sailorchic34
The blonde engineers take is that if they are all 12V 6 cell lead acid batteries, it will make no practical difference. You can mix group 24's, group 28's and group 31's wet cells and the charge and discharge voltages will be the same. well close enough to make no difference. Internal resistance varies a tad, but not too bad.
I would wire the battery's so that the dual purpose and starting batteries were on separate branch circuits and not intermixed, but they could be then connected together for one big happy family
It's far more important that the batteries are wired so they all see the same voltage drop across the wires. Generally that means + tied to one end and - tied to the far end, with parallel straps the same length and size.
I'm pretty sure the blonde engineer
got it right. Is that where the term "electric blonde" came from?
I think there may be slight differences between equalizing voltages and possibly acceptance voltages between different manufacturers and different models, but I doubt you are equalizing your batteries anyway. Go read everything MaineSail has written if you want an answer from someone who actually knows.