questions on adding a second battery

[doghouse_riley]

i have a new 4WC Fleet shell that I'm in the process of outfitting. It has the standard 79 amp hour AGM battery (Deka Intimidator). I'm only running the lights, fan and shurflo pump for the sink and cabinet I just built. Putting a 200w panel on next (plus charge controller). I expect to be adding a fridge and likely a heater in the near future, and possibly a 110v inverter (though I don't expect it to get much use)

I figure I'll need to add a second battery and had a few questions:

I understand there could be an issue with adding a new battery to an older one. How old is old? Right now we're only talking about a few months with little use. Should I just add it now?

How closely does the new battery need to match the existing? Same voltage, obviously, but same amp hours? Same brand ideally?

What's the recommended gauge of wire to go battery to battery?

Any need to upgrade fuses?

Thanks!

 

[Vic Harder]

i have a new 4WC Fleet shell that I'm in the process of outfitting. It has the standard 79 amp hour AGM battery (Deka Intimidator). I'm only running the lights, fan and shurflo pump for the sink and cabinet I just built. Putting a 200w panel on next (plus charge controller). I expect to be adding a fridge and likely a heater in the near future, and possibly a 110v inverter (though I don't expect it to get much use)

I figure I'll need to add a second battery and had a few questions:

I understand there could be an issue with adding a new battery to an older one. How old is old? Right now we're only talking about a few months with little use. Should I just add it now?

How closely does the new battery need to match the existing? Same voltage, obviously, but same amp hours? Same brand ideally?

What's the recommended gauge of wire to go battery to battery?

Any need to upgrade fuses?

Thanks!

Craig is the battery guru, but I would say your camper is newish, so chances are that a "new" battery you add to this setup will be fine. Same brand & type (Deka, AGM, deep cycle) would be ideal. If there are differences, the batteries can't possibly be (dis)charged the same at any given time.

Distance between the batteries is important. If you are putting them in the same battery box, you want the wires between them to be bigger than the wires going to the loads for sure. I'd use 4g at least.

More importantly, wire the loads to the +ve terminal on one battery and the -ve post on the other.