Battery replacement

[BHT]

My 2017 Macan Diesel could do with a new battery.

It seems replacing the battery is not as simple as just replacing the battery. The new battery has to be coded back to the car so the car knows how to charge it correctly.

If I was to buy the exact same battery and during the replacement process I connected a charger in 'supply mode' so the system was never without a 12v supply, how would the car know the battery had been replaced? Would doing it this way negate the need to 'code' the new one in?

Anyone here done this or is it a trip to the main dealer?

[PowerMalc]

I did something similar on a Boxster 981. I used some jump leads to connect the second new battery to the car's terminals which I had placed in the bottom of the boot.
I then disconnected the original battery while it was in its car tray and removed it. New battery raised from boot into battery holder still connected via jump leads and then car's + and - leads connected. The car's electronics never 'knew' a new battery had replaced the old. No recoding required.

[smithers-jones]

Main dealer is not required. Even if there is a code, which is unlikely, any garage with obc2 equipment (basically, all) can reset the car. For peace of mind, use a local garage to do the swap and ask them to check for any fault codes and reset them.

Usually all the car computer has done is manage electrical loads as the battery starts to become weak, and usually things like heated rear screen, seat heater, radio etc are turned off to preserve the ability of the alternator to support the weak unit.

I recently swapped a battery on my Alpina: similarly everyone says it needs coding. It didn't. Removed old, put new in myself, took it to my friendly indie, he plugged it in and there was no code to reset (as we both expected). You don't need to use a dummy battery on the car during any swap, and that can be dangerous if the leads are flopping about whilst you're trying to remove the old unit. Just disconnect in the correct order (negative first off, reconnected last) and swap it straight over. I've never paid anyone to replace any battery in any car I've owned: simple job. And this coding thing is manufacturer's trying to scare owners into spending more than they need to at their service centres.

[Madelvic]

I'm likely to have to replace mine soon too. Good write-up on the US Forum here:

https://www.macanforum.com/threads/diy- ... nt.180875/

My chums pointed me at this clip; 6 mins 48 in.

[BHT]

A quick follow up on this one.

I read somewhere that the smart alternator only charges during engine braking. Now, as my Macan is currently only used for short (5 mile) runs it clearly wasn't getting enough charge.

I connected up a Ctek charger to it which took two days to fully charge the 105ah battery. That was 2 weeks ago now and I haven't seen the 'Battery Low' warning since.

[Nuclear Nick]

A quick follow up on this one.

I read somewhere that the smart alternator only charges during engine braking.

Where did you read that? The alternator charges immediately on starting and continues until the battery is full charged, provided the engine is running above tickover speed. A low battery will take at least 30 mins continuous running to top it up.

[EngineerMK]

My 2014 Cayman recently needed a new battery (OPC identified low battery voltage was causing door mirrors to be lazy when unlocking car?). OPC quoted £450, I replied I can buy BOSCH battery for £250. Line went dead for couple minutes and then OPC offered to price match inc fitting. Its worth asking them to price match.

[Cobnapint]

A quick follow up on this one.

I read somewhere that the smart alternator only charges during engine braking.

Where did you read that? The alternator charges immediately on starting and continues until the battery is full charged, provided the engine is running above tickover speed. A low battery will take at least 30 mins continuous running to top it up.

After charging mine this morning, I noticed on my first drive that the battery voltage rose mostly when I was off gas (ie engine braking) or actually braking.
This is bonkers, if I'd wanted an EV I'd have bought one.

The car will of course charge at other non braking times as the battery deteriorates but it is rather petty only charging in bursts.