Tapping into power terminal under hood

[spoolinX1]

I need to wire a constant power relay to the terminal under my hood. I've never done this before in a BMW. Do you guys recommend disconnecting the negative battery terminal (in my trunk) before doing so, or should I do it live? I just need to slip a ring terminal around it.

I've read that our batteries are programmed by BMW (?), so with that said, are there any negative factors involved with disconnecting the negative terminal.

[Riche3]

If you are not sure , then get a professional to carry out the task in hand or go and ask the advise from some one in a bmw dealership .
Better to be safe than ... Sorry , You know what i mean

[Njerts]

I dont think it is a problem disconnecting the battery. All the guys installing JB4 recomend that you disconnect the battery.

[Njerts]

Also I am lazy, I would do it live.
Just make sure whatever you connect is not touching body or anything else and make sure you add an inline fuse.

[NorCal Einstein]

There should be no problems with disconnecting the battery before work (battery located under the cargo liner). Yes, the batteries are branded/coded/registered/whatever to the car, but that only becomes a issue when you need to replace it.

[Mr Kleen]

Originally Posted by NorCal Einstein

There should be no problems with disconnecting the battery before work (battery located under the cargo liner). Yes, the batteries are branded/coded/registered/whatever to the car, but that only becomes a issue when you need to replace it.

You should always disconnect the battery when doing any electrical or "serious" mechanical work. It only takes a minute and it could save a LOT of trouble if things go wrong.

[spoolinX1]

Excellent. Thanks for the info guys. Common sense tells me that the battery should definitely be disconnected, but I became nervous after reading that the battery was mated to the vehicle.

[spoolinX1]

You guys were absolutely correct. For future reference, if anyone needs to tap into the power terminal under the hood, you can disconnect Negative battery cable in the trunk (10mm socket) with no side effects aside from having to reset the clock. Car retained all other settings.