running air compressor from aux battery

[XJeepers]

After some advice from those in the know

I have my aux batts in the back, charging from the VSR. I have just about finished installing my drawers and the air compressor will be sitting next door to the aux battery.

I am not sure if its ok to run the air compressor from the aux battery (I only use to air up after offloading) or should I be extending the wiring to run it from the start battery to get the amps from the alternator with the car running?

The air compressor is rated at 45amps max.

[CreepersJeepers]

The aux battery should be seeing charge from the alternator anyway and 45 amp Max draw shouldn't bother it anyway...

I'm planning on installing a compressor up back off of my secondary fwiw

[junglejuice]

What size cable are you running front to rear?

[XJeepers]

6B&S cable

[junglejuice]

I would have run larger cable personally, do you plan on running the compressor with the engine running or not?
I ran 35mm2 (approx 2AWG) cable front to rear of mine to try to reduce voltage drop as much as possible, my compressor is rear mounted along with my aux battery and controller....

[anthonygubbin]

I'm running 8bs and I can't notice any significant voltage drop; maybe .1-.2 but that is going through an aux under the bonnet first as I have three batteries. I have a 45a compressor running off the front aux with 8bs cable leading up to it.

Regards A

[XJeepers]

I have measured the voltage and it is bugger all difference. I was more concerned about the amperage being available to the compressor. But now that I think about it, the car will be running when I am using the compressor any way, and the VSR should have the batts connected, hence it doesn't really matter which batt the compressor is hooked up to right?