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Well, the discussion had gone through the points of shorting the battery not mattering (to the ECU) and why welding could be a bad thing. As such, the concept of 12v being the killer was no longer pertinent (at least to this discussion).

Yeah i think i'm saying no shit because you don't think i could possibly understand that a welder puts out a lot of voltage....sorry thats the way you came across to me.

When a workshop welds on your car's exhaust etc, they fit a surge protection device across the battery terminals.

These days everything is DC so you never hear of alternator diodes cooking, was very common back in the AC welder days.

I'm yet to receive an iron clad guarantee from any workshop that if they blow my ecu they'll replace it.

So I unplug mine.

Yeah i think i'm saying no shit because you don't think i could possibly understand that a welder puts out a lot of voltage....sorry thats the way you came across to me.

No I was just thinking that you'd skipped over the fact that we were talking about welders by that time.

So it's impossible to damage the ECU then by shooting the battery.

True as long as the engine is not running. Any changes to battery connections (including that tool generated short circuit) when the engine is running can create load dump whiich has been defined by ISO and SAE to be as much as 270 volts. Latest numbers have lowered that to (if I remember) something just under 100 volts.

Automotive electronics therefore also meet higher voltage requirements. For example, 5 volt regulators must withstand something like 60 volts without damage.

Never make electrical changes (not including a jump start) if an engine is running.

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