I shall be fitting a new battery tomorrow to my 95 sti.
option 1. ( ignition off )
Just remove battery and fit new one.
Problem.
Have the hassel of re-setting alarm,tracker and possibility of ecu re-setting its self.

OR

option 2. ( ignition off )
change battery using jump leads from car to new battery therefore never losing power to the car , which should cancell out all the above problems.
Problem.
For a short while both batteries will be connected to car giving off 24 volts. Can this harm anything ?.

I will be grateful of any advice or better ideas you may have.

thanks guys.

 

I changed mine a while back and never though about ECU's etc.
No problems and everything worked fine after.
Think most units have a small internal battery to memorise settings etc for a short period of time.

Chris

 

If you are connecting the batteries in parallel using jump leads (the usual way for a jump start) + to + on the battery terminals and ground to ground on a grounding point then you will only ever see 12v at the terminals.
You will be fine, you won't loose your radio stations or need your code if you have a coded radio.
If you don't have a coded radio I would'nt bother, it will all come back to life again after.

Dipster