I have just wired up my LFP bank. At present its only connections to the
boat are on the negative side to my multiplus 2
inverter charger and through that to the common negative via the earth for that unit, and to the 12DC for the
boat on the positive and negative. So 3 connections to the boat 12V in total. There are literally no other connection between the LFP bank and the rest of the boat except to the AC 230V system through the
inverter.
On the positive side between the bank and the 12DC system there is a
battery protector that is refusing to connect the LFP bank due to the presence of a short circuit. Sure enough, upstream of the main 12V DC breaker but downstream of the protector there is zero resistance between the positive of the LFP bank and the positive of the
engine battery. These should be entirely disconnected from each other (infinite resistence).
Currently the battery protector is doing its job and so no damage is being done but its annoying not being able to run the 12V off the
Lithium as intended. I just can't see how these banks can be connected except through the common negative earthing to the
engine block. But why on earth (excuse the pun) would that generate a short between the two
batteries?
I'm getting to the point of just disconnecting the
AGM battery entirely and going all
lithium to solve the problem. That should solve it, but at the loss of an
AGM battery for anything other than
emergency backup. Anyone have any (brighter) ideas what the short could be?