MURPHY55347 wrote:
Batteries are connected in parallel so you only need to disconnect the one negative cable that goes to chassis ground. I use a disconnect switch like this. You just partially unscrew the green knob and it disconnects the battery.
https://www.zoro.com/battery-doctor-battery-disconnect-switch-negative-12v-20308/i/G3024804/
True batteries are in parallel on our trucks (12V DC), but that does not mean that there is just one ground for both. I know this for sure on the Dodge with Cummins as each battery is grounded to the engine block, not sure how Ford grounds theirs.
