battery kill switch and MS3 Pro

[MegaSlant6]

Hello,
I have a MS3 Pro in a car that I have relocated the car battery to the truck. To be in accord with the local track rules I have installed an externally accessible battery disconnect switch that interrupts the positive battery cable.
I currently have the MS3 Pro powered directly with a fused wire off the battery, so it is outside of the disconnect switch. I did that, as did not know if shutting down the MS3 Pro with the battery disconnect would be harmful to the MS3 Pro,,, or is that basically the same as turning off the key, a normal shutdown.

thanks

[DaveEFI]

Powering it through the master switch will be fine. Thing to be avoided is some things powered up with MS powered down - as it may still supply a ground to a relay etc when switched off.

[Matt Cramer]

It's basically the same as shutting off the key. The main concern can be voltage spikes from the alternator, depending on how that is shut down.

[MegaSlant6]

voltage spikes from the alternator

the alternator field wire also goes through the disconnect, so the alternator output stops when the disconnect is switched off,,
the engine dies immediately when the disconnect is switched off.

so I should be OK running the MS3 Pro through the disconnect.

thanks for the quick responses.