Best way to disable 12v battery.

correct forum is......(drum roll)...........

Gen 2 Prius Care, Maintenance and Troubleshooting | PriusChat

 

The reason to disconnect the negative side first, is that if you short the battery terminal to the body with the wrench, there is no impact if the negative cable is removed first.

If you "unplug" the positive side first and there is no risk of shorting the positive battery terminal to body ground while the negative cable is connected, that is OK.

 

Do you mean: if you've remove negative cable clamp from the negative battery post, and subsequently have a wrench on the positive battery cable clamp that inadvertently touches the body, there is no problem?

So on the positive side a quick-disconnect of the cable at the positive post is possible? And as long as that loose cable doesn't subsquently contact the car body you're ok?

Still, I think I'd go with negative disconnect first, and stuff any loose cables into heavy rubber gloves, for shielding.

And for removal or install of batteries, deal completely with one connection first (my preference would be positive disconnected last and installed first): ie install and torque the clamp on the post, before moving to the other.

One time I installed both clamps loosely, on a jump pack battery, and got a nasty suprise: torquing the positive clamp when the negative clamp was loosely installed. My ratchet wrench extension touched a wire running back to the negative post, fused it.

 

Correct.

Also correct as to the first sentence. Regarding your second sentence - I corrected my post, it doesn't matter if the cable touches body ground. What matters is if the positive battery terminal contacts body ground while the negative battery terminal is connected to body ground.

I further agree that good practice would have you tighten one connection at a time. Do not place both cables loosely on the battery terminals, then tighten them. Rather, install the positive cable and tighten the connector. Then install the negative cable and tighten its connector.