12v motorcycle batteries, or 12v forklift batteries, or somewhere in the middle? Need the capacity (generally stated in amp-hours) of both of them, not just the voltage ...

On the alternator side, 180 amps at nominal 12 volts is about 2.2 kW, so your load may be capable of running the batteries down even with the charging system operating.

Typical alternator requires running above specific engine rpms to achieve their rated output.

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Two red top optimum car batterys. They are in a 2014 ram 5.7 hemi. I think about 1000ah each.

That's not plausible. That's probably the cranking-amp rating. You are looking for the amp-hours rating.

Which one? https://www.optimabatteries.com/en-us/redtop-start...

It's either 44 A.h or 50 A.h ...

If you are using two of them and it's the bigger one, that's 100 A.h of capacity, and nominally the time to recharge with a 180 amp supply (and zero load!) is (100 / 180) = 0.55... of an hour ... That's plausible.

You are never going to have all 180 amps available to charge the batteries. Just running the engine and accessories will take quite a bit of that output what with lights, fans, electric power steering, fuel injection, etc. Hopefully the batteries are never fully discharged either or they won't be long for this world. Whether or not the alternator can keep the batteries charged up depends entirely on how much load the amps are actually pulling. Music is an incredibly dynamic load and just changing the volume 3 dB will change the power consumption 2:1.

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↑↑↑ peak load is probably why ultra-capacitors exist.


Norm

Correction, yes they are 50ah each.


I have always been told that in car audio batterys Vs capacitors you should always do batterys... capacitors are fine for lower watt systems but once you get over a certain RMS multiple batterys and larger alternator(s) are the best..

Is the power steady-state or transient? Note that 20 Ah at 500A draw is 144 seconds.

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will play a few songs while driving around town or interstate. So few songs with bass turned up then maybe a few minutes with no bass volume low and/or off. So maybe 50% roughly of my commute is full blast.

Invest in hearing aid stocks.

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You wouldn't even get 144 seconds due to Peukert's law.

Cheers

Greg Locock


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So is it safe to say roughly 15min on 30min off during a normal drive? Along with twice a week take sign language classes lol (dgallup)