Confirm my dual battery thoughts....

[deeve]

I want to create a DIY dual battery setup in my JK using the $50 DIY system outlined here. My plan is to have AUX stuff like a winch, fridge, CPAP, lights, etc. to a deep cycle second battery that is connected via a relay so that it is connected and charging when the engine is running...or I can use a solar panel to charge it eventually. My main battery is still pretty new so I was not planning on replacing that. The second battery will probably be a group 34 deep cycle. It is my understanding that the way I am planning on connecting and using these it is ok to have a mismatched battery, correct? I think once back home I will connect that second battery to a tender to top it off, or maybe that isn't needed?

Thanks!
DAVE

 

[luthj]

Assuming you have a charge source, you can connect most any 12V nominal battery type in parallel. Even a lithium unit. As mentioned, disconnect when the charge source is off.

Take note that the voltage of your alternator will determine how quickly, and if your second battery will get recharged at all. At least 14.1V. Ideally ~14.4v depending on battery type. If its below 14V, you will need a shore power charger, or solar to get it fully charged after usage. Otherwise the second battery will not last very long.

Voltage drop in the charge circuit for the second battery can cut charge current in half or more. So pick decent sized cables. I would aim for 1% drop at C/5 (C= batteries 20 hour capacity rating).

 

[deeve]

Thank you.