TIMBERHOLLOW9310

Latest Panorama mentions in tech talk plugging a 12 volt power supply into the OBD II port via diagnostics line. Does not name any brand, cost, etc. thinking of changing my battery wondering if hooking up a spare battery using the dead-battery-trunk-method would do the same thing.

Fahrer

Some folks use a battery maintainer plugged into a power socket that is always hot ( generally the cigarette lighter). Others simply installm the battery without backup power ( safer) and let the car re-set most things, itself. You will need to re-set the power windows (easy) and possibly radio memories.

Devil Boy

I've never lost any memory settings when I have disconnected or removed my battery. Other than having to reset the windows, nothing remarkable happens.

jcnesq

I wouldn't worry about it at all. Just changed my battery and other than windows and a very brief time for the computer to reset a few things, you won't even notice.

Nothing to see here, move along.

PhilD

X2 It is no big deal changing/disconnecting the battery.

stronbl

Did a battery change last week (2010 997.2) and used my CTEK maintainer connected to cigar outlet. After I removed my battery and before installing the new one, I noticed the power light on CTEK flickering just as if I have disconnected it from the cigar plug but left it connected to the wall outlet. In other words, no charge was maintained. Installed the new battery and started up the car ... all radio and seat memory were fine, even default Nav settings. Only had to reset window end positions and drive around the block to reset PSM.

As others have already said, no big deal.

semicycler

The charging circuit inside the CTEK is "intelligent". It needs to sense a battery present to charge, something like 9V minimum. It also won't do any harm to the battery if you connect it backwards - just no charging.

The drawback is as you discovered - it's useless to maintain 12V without a battery present.