Lucky Max (Starter Draw)

[hsburt]

I'm currently researching isolation switches for the boat's battery banks and am getting some conflicting opinions on the amp rating on the switchs. It seems to have boiled down to how much amperage each starter draws while the engine is cranking. Any thoughts folks please?

Thanks
Steve

[john8662]

The starter uses a lot of amperage.

The starter solenoid doesn't use that much. Something in the 25amp range should be sufficient for the starter solenoid excitement.

J

[JohnC]

If you can't bypass the isolation switch for the starters, bear in mind the isolation switch will not be switching the starter current, just carrying it. The starter solenoids will do the heavy switching.

[NH2112]

IIRC a 27MT (direct drive) starter on a 6.2l draws about 400A, and a reduction gear 28MT is about 300A. That's on 12V equipment, 24V stuff would obviously draw about 50% as much.

It's overkill but when I load test batteries in diesel equipment at work, I put the full 500A load on.

[Kennedy]

Most competition vehicles use a large rotary switch to shut off teh entire electrical system so this should work fine for just a starter. Might keep a spare on hand just in case.

Google flaming river battery switch