I have 2 - 12 volt Dakota Lithium 100 AH batteries wired in series for the 24v trolling motor and each battery has 2 additional loads for the 12 volt loads on the boat. Each battery has it's own Dakota 10 amp charger wired to each battery. Where or how should one wire the Victron 712 into the system? I'm not opposed to just monitoring one battery and "assuming" the other one is close or would I need two 712's to actually monitor each battery. Thanks IA.
The 712 measures current and voltage of a single main battery, or bank that looks and behaves like a single battery. The monitoring of a second battery is limited to voltage and it must share a common earth/ground to the main battery for that 712. Alternatively instead of a second battery it can measure the midpoint voltage of a 24V bank of 12V batteries. To calculate state of charge it must see all the current passing into and out of a battery.
In terms of the 712 you have three batteries. And three electrical systems. And no charger for the 24V battery.
Whatever you do will be a compromise.
A single unit could measure the 24V battery and midpoint. But cannot be connected in your system to give state of charge. It could instead be wired for the 0-12V battery for accurate SOC on that battery and I think, treat the 24V as an aux battery.
Two would monitor each 12V battery for voltage, but neither would give accurate state of charge for the entire system. I'm not sure, but I think you could treat the 24V as an aux battery to the 0-12V battery.
Three would give a complete voltage/current picture, but again no accurate system state of charge.
You gain little except more gauges by fitting more than one 712 to the 0-12V bank and treating the 24V as an aux battery. But check that you can use a 24V aux battery on a 12V system.
