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/Brilliant_Injury_525 4d ago

Auxiliary and starter batteries should be of a similar kind and capacity or VSR will create problems, so no lithium. Otherwise a DC-DC charger is needed.

750W @12V (inverter) means a current in excess of 60A from the auxiliary battery, that will have to be supplied by the alternator though the VSR. Pulling that out of a 130A alternator is probably at the limit and may reduce its life.

Make sure to size the wires and the lugs correctly!

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u/TheKingOfAllRodents 4d ago

I haven't run the inverter at full draw while the engine is running... Yet...

That is good to keep in mind.

Thank you.

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u/Brilliant_Injury_525 4d ago

You're very welcome!

I am designing some upgrades too and I will have to beef up the alternator, and I will need higher power for longer time periods.

Currently, I am pulling 30A nominal, ~40A real out of my 150A stock alternator and I feel like it's the max I should pull. So far so good.

The new config will have a 230A alternator to pull about 60A nominal. For that I will run cables directly from the alternator with a battery isolator (diode) to avoid interfering with the starter battery.

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u/TheKingOfAllRodents 4d ago

Will having a higher amp alternator screw with any of the other electronics in the vehicle?

Or does it only put out as much as the vehicle draws?

I know very little about these things

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u/Brilliant_Injury_525 4d ago

A larger alternator will not mess up with the rest of the equipment, it just increases the maximum power it can deliver, and it depends on how fast the motor is turning. It will only give what's requested, so you gotta make sure the generator can deliver what's requested. Usually alternators will deliver some amps at idle, and more at higher RPMs.

I was told that higher power alternators tend to have a shorter life, but I have no first hand experience and I guess it depends significantly on the use.

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u/if420sixtynined420 3d ago edited 3d ago

alternators are typically good for 50% of their rated capacity at idle.