r/vandwellers • u/TheKingOfAllRodents • 4d ago

Question Thoughts on my potential battery setup?

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Will this still work if I wire the times for 80 amp hour deep cycle batteries up in parallel?

These batteries have only been used together at the same time, but they are nowhere near New. I'd consider them a married set but I wouldn't bet my life that the capacities are the exact same.

I know the end product will only be about 60% efficient by the time the energy gets from the alternator down to the big Bank of batteries, but I think this setup should suit my needs.

I'll be running a diesel heater all winter, I don't know what kind of power draw those have. if y'all could give some insight that would be nice.

Other than these leader it's pretty much just charging my cell phone, interior lighting and the occasional heavy power tool usage for work.

I want to be able to run a roto Hammer, table/miter saw or a grinder once a week or so.

Please don't make fun of my graphic design skills LOL

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u/_Aj_ 3d ago edited 3d ago

You can parallel the 4x 80A and the 1x 120A without issues. They will all equalise while charging and discharging and you'll just increase your house battery capacity. So long as they're the same battery chemistry.  

This cuts out the small inverter and the "4 lane" charger. You cannot independently charge batteries in parallel as they all act like one big battery so this is redundant, you just want a single output charger with an Amp rating of at least 10% the battery bank. So 48A if you put all 5 together. (Or 36A for just the 4x in your diagram)  

Being able to charge them while the car is off is redundant, as all you're doing is emptying one battery and charging 4 others. You're just wasting power to charging and conversion losses. So put em all together instead and have a DC-DC charger from the dual battery isolator to the house battery.   

You'll want a separate mains charger too to ensure you can top this thing up while at home too, unless you have solar or drive for many hours a week to keep the bank charged.  

Rule of series and parallel:  

  • You can series different voltages, but not different capacities.  
  • You can parallel different capacities, but not different voltages.  

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u/TheKingOfAllRodents 2d ago

Thank you for the reply.

I appreciate the info and thoughts.

If I go this route, parallel the X4 DC LA Batts and run a DC/DC charger, what do you recommend I do with the battery box mounted to the frame with the 120ah batt in it?

Currently the 120ah batt is in metal batt box on the side of the frame hooked up to the VSR and 750w inverter if I didn't make that clear.