Frederick NL

On a German forum I saw a suggestion, related to exchanging the rear battery. By putting something like a 10W lamp in series with the earth lead, just before connecting that lead, one softens or eliminates a surge (usually you see sparks) when connecting. Apparently, electrolytic condensers in the BCM will be thankful.

I’m sure others can elude.

I don’t know about DISconnecting, and if the same goes for the starter battery. Sure, it’s business is cranking only, but there’ll be circuit there too, right?

bobterry99

I think the voltage spikes which accompany the sparks you see when a cable is connected are well-tolerated by the vehicle electronics. And I can't think of an instance where someone's vehicle was damaged by connecting a battery.

Frederick NL

I see. But R230’s and undoubtedly other cars do suffer from gremlins the origin of which often is obscure (origin as opposed to diagnosed problem, remedy and so on). Just my thought, as an electronic no hoper.

Rudeney

That little spark you may get is no big deal as long as you go ahead and complete the circuit. However, if it scares you and you jerk away, and then drop the cable, and let it sit there and flop around and stutter on the battery post and create a shower of sparks, that can be a problem.

bobterry99

In my '91 SL500 I added a microcomputer-controlled circuit which allows the transmission to automatically start in 1st gear instead of 2nd. It was a trivial matter to design protection from voltage spikes for the circuit. I presume every electronic module in a modern automobile has such protection.