Q1: I would like to add a second battery to my current 12v system. It currently has a 210ah agm and I was wondering if it would be best to wire the second one in as a 24v setup or keep it simply as a 12v?
Q2: If I did do a 24v battery setup will my 75/20 automatically output 12v or will it only do a 24v output without another device to covert it?
Regards
To Q1:
It depends on your usecase. Sometimes 12V is the better option, sometimes 24V make more sense.
To Q2:
The output is everytime Vbatt. If 12V system the voltage could be between ~12V and ~14.4V depending on your battery settings. If 24V system the output is double.
Btw:
For 24V System the battery's need to be the same capacity and in best case the same manufacturer and model. You also need a battery balancer to avoid damage to your battery's because of different state of charge that can occour.
Q1: If you need 12V output, It would probably be simpler to wire your batteries in parallel keeping the whole system 12V.
Make sure the batteries are the same capacity and charge level before hooking them up.
12V has the benefit of allowing you to capture more charge during low light.. But this is dependent on your panel sizing.
Q2: Your 75/20 will always output battery / charge voltage through the load port. So 12V battery, 12V load. 24V battery, 24V load.
