First, I used the wrong term. I called it "electronic battery control module", what I meant was "electronic battery sensor". Modern cars have a battery sensor connected to the negative terminal (often not right at the terminal, but further down where you can't see it).How can connecting a jumper directly to the battery terminals damage the battery control? Jumping is like temporarily putting in a new battery, no?
Yes, the main purpose of connecting the negative cable clamp to the engine or body metal of the dead battery vehicle is for safety reason. Another minor benefit is to eliminate any possible bad connections on negative battery post (i.e. corrosion at post area) or any other abnormal resistance on negative wiring to the starter of the dead vehicle during jump-start which requires substantial electrical current.Whether you connected the black jumper cable to engine or body metal, or directly to the negative battery post matters nothing to the car. You connect to engine or body metal simply so the sparks are farther away from any hydrogen gas hanging around the battery when it is in a discharged state. Few want a dead battery and shrapnel.
Yes, I agree. And I‘ve said so in my early post in this thread.Yeah, this battery/charger rabbit hole is a waste of time, guys. OP, did you measure the non-running and running voltage at the battery?
I'm with tibi, in that something else has changed other than this jump start event.