Can you fully disconnect the battery when changing it?

[flagger]

Hi all, my original battery on my 2013 Golf is starting to give indications it is on its last legs and my experience with sudden battery failures, I have decided to swap in a new one. I have ordered a OBDEleven which should be here next week so I can update the coding and will probably get the Century DIN65LH AGM battery, which I can get locally at a decent price.

I read in a few places, that the BCM module on the negative terminal should be kept powered on while doing a battery change. Do I really need to keep it powered? Seems a bit overkill to me.

[Transporter]

There's no need to keep power on, though you'll have to clear the fault codes and restore windows anti pinch feature. If you have s/s system you will also need to code the new battery in.

[flagger]

Thanks for the quick reply Transporter. That's good I guess, I am used to dumb battery systems. So the car will throw some faults on first start up after the new battery is in? I assume that I can just clear the codes straight away with the OBDEleven. Did not even know about the windows anti pinch feature. I hope that is programmable with the OBDEleven too.

[Transporter]

You just roll the windows down one by one, continuously while holding the window switch and up the same.

[flagger]

Ahhhh, thank you! Would not have known that about the windows thing.

[mr gee]

wind down and hold for 5 secs. wind up and hold for 5 secs
that should let the system learn the settings

[xradioactiveman]

Hi all, my original battery on my 2013 Golf is starting to give indications it is on its last legs and my experience with sudden battery failures, I have decided to swap in a new one. I have ordered a OBDEleven which should be here next week so I can update the coding and will probably get the Century DIN65LH AGM battery, which I can get locally at a decent price.

I read in a few places, that the BCM module on the negative terminal should be kept powered on while doing a battery change. Do I really need to keep it powered? Seems a bit overkill to me.

Sorry to bring up old thread. I just replaced with same battery. Did you end up coding it? Just wanted to know what details to enter such as serial, manufacture etc as century doesn’t have bem details. I have stop start system btw.

[DV52]

@xradioactiveman: hmm........ given the age of the post that you have included, you might not get a response from @flagger. I've just read this thread and there appears to be a number of mis-understandings in the questions/responses. (BCM isn't connected on the negative terminal- and the module that is on the negative terminal (J367) doesn't need to be separately powered when replacing battery)

As for your specific questions, if your new battery doesn't have a BEM sticker, do this:

• Battery adaptation-Rated battery capacity > change to capacity of new battery
• Battery adaptation-Battery technology > change to "FLEECE" for AGM (I assume this is the technology for your "century" battery - as per OP)
• Battery adaptation-Battery manufacturer > not important
• Battery adaptation-Battery Serial Number > actual number not important - it's just necessary that the number is different to existing value (suggest you change anyone of the digits to another number)

Don

[gregozedobe]

Its a great idea to replace your battery as soon as possible.

But only when it needs to be replaced, typically when it won't hold a decent amount of charge even when placed on a charger for a long enough time (which can be many hours if the charger can only supply a small amount of charge).

The best way to test a battery is with a true load tester (like a 12V toaster that produces a lot of heat while testing) after the battery has been fully charged.