Wednesday, Mar 25, 2015 at 23:24
I have a deep cycle under my bonnet as a second battery which generally runs flat overnight, even with the fridge turned up to around 5 or 6 degrees.
An autosparky mate told me its a waste of time if the alternator is charging the two batteries together as the deep cycle needs more volts going into it that the cranking battery, so once the cranking battery is charged, you won't get any more into the deep cycle, and therefore it never gets fully charged.
He reckons you either need a more sophisticated system that takes account of this, or a far simpler manual one, involving a boat switch, so that you're not charging the two different battery types together. Can anyone verify this?
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