Hello all. I just installed my Renogy 60A DC-DC charger and after a couple days I am seeing why a lot of people install a switch for when the charger is actually needed. I may be overthinking this but where do you run the negative from the switch? Does it run straight to the DC charger or do you connect it somewhere else?
Another question, my Battleborn batteries state that 14.4 is optimal charging voltage. So when my monitor says 14.4 and the DC charger kicks off, should I tell the monitor at that point that the batteries are at 100% capacity or wait until the voltage drops to 13.3 then program the monitor to 100% capacity.
@RPR006 I installed the Renogy 40A DC-DC charger in my van and for switching I have installed a separate manual switch instead of connecting it to the ignition on live feed. Personally, I think it’s a better way because it gives me some element of control over charging batteries using the engine. Generally, switching it on when starting and off when stopping the engine has become a routine.
But in answer to your question…
The negative wire from the switch (which takes its power supply from the vehicle side of the system) can be connected to any earthing point on the vehicle as this completes the circuit for the switch to function provided that the negative high current wire from the starting battery or earthing point is connected to the charger.
If you haven’t already done so it might be a good idea to install a switch that displays a lit LED when it is switched on to remind you that the circuit is closed when you shut the engine down because there was one instance when I left it switched on overnight without the engine running and it resulted in full service batteries and a dead flat starting battery the next morning…and that was WITH an LED switch!
If this happens, you will need to rebalance the DC-DC charger by disconnecting both positive and negative wires from both sides of the charger and then reconnecting them, so make sure the charger is locate in a place with easy access!
And because I have only ever installed lead acid and AGM batteries in my van, I have to admit that I don’t have experience with lithium batteries and therefore won’t attempt to answer your second question.