2017 c4 GP battery replacement. Advice needed.

[Alexsjob]

Hi all,

I need to replace the battery on our 2017 c4 GP. It's a diesel with start stop.

I can do the switch myself but noticed that the manual says a mechanic should do it and I'm concerned that if I change the battery specs (which I want to), the software needs to be updated.

We live in Sweden with cold winters. The diesel heater is draining the battery and the start stop system hasn't worked for a couple of years. Therefore, I'd like to replace with a 80Ah agm battery. Unfortunately I don't have the specs for the current battery, but I strongly suspect it's 70-72A and probably not agm.

I've seen the procedure on how to do the switch and it seems pretty straightforward. But the two main things that make me hesitate are

* does a change in battery specs (amps and agm) require updating software settings
And
* what amps to go for. To me, going for 80 instead of 70/72 seems to be a smart move, but I'm still in need of some community guidance.

Any thoughts on this? Love to hear from mechanics or owners that have made the same switch.

Thanks,
Alex

[GiveMeABreak]

The battery charge status unit will need to be informed if a different battery is installed to that already fitted at factory, as this unit supplies the BSI with battery health data to allow the BSI to fine tune the energy management system.

Pop your VIN up so I can see what it is supposed to have.

[Alexsjob]

Wow, thanks! It's VF7**************[VIN obfuscated, can be read by forum staff]

[GiveMeABreak]

So your vehicle was originally factory fitted with an AGM battery. It is a L3-70AH-760A-AGM type for reference.

But don't forget, this vehicle is also showing has having the additional ultracapacitor system, converter and ECU, located inside the front left wing hidden away under the wheel arch protector. So this unit is an energy accumulator, storing energy for the stop start. Be careful if exploring as these hold about 600Amps! So must be discharged with appropriate tools before handling.

Stop Start does require a lot of pre-conditions and external temperature and demand on passenger electrics / heating will often prevent it from kicking in.

[Alexsjob]

Thanks so much!

Think that info is enough for me to hand it in to a mechanic for the switch..

[Alexsjob]

So your vehicle was originally factory fitted with an AGM battery. It is a L3-70AH-760A-AGM type for reference.

But don't forget, this vehicle is also showing has having the additional ultracapacitor system, converter and ECU, located inside the front left wing hidden away under the wheel arch protector. So this unit is an energy accumulator, storing energy for the stop start. Be careful if exploring as these hold about 600Amps! So must be discharged with appropriate tools before handling.

Stop Start does require a lot of pre-conditions and external temperature and demand on passenger electrics / heating will often prevent it from kicking in.

Sorry, one more question. Is it possible to switch the battery without touching/having to discharge the energy accumulator units? At first I felt deterred, but thinking about it, it really shouldn't pose a problem if I'm just changing the battery, right?

[GiveMeABreak]

The main vehicle battery is completely separate from the energy accumulator which is not supposed top be touched by the owner. I only mentioned it in relation to the Stop & Start issue that you mentioned in your post, as to a possible other reason why S&S is not working.

You can go ahead and replace your main vehicle battery without any regard for the Stop & Start system equipment. Just make sure you follow the BSI Reset / Battery Disconnect / Reconnect Procedure to prevent any electrical issues.

[Richard_C]

I don't know about prices in Sweden, but when I had to replace the battery in my 2016 un-grand Picasso the dealer cost was only a little more than buying the battery from a parts supplier and fitting it myself. I had a quick look and seeing how much stuff you have to move aside and how deep under the bonnet the battery is, I decided it was worth the money. The GP might have a slightly different layout and longer bonnet, but I wasn't looking forward to lifting a big heavy thing out of the space.