Good grief, does it really need to be that hard?

[corsechris]

Just replaced the 12V starter battery on the tin top. I specify starter battery as it has an auxiliary 12V ‘battery’ as well, that’s actually a super capacitor and a 290V battery for the hybrid drive. 
 

In their wisdom, MB stuffed the 12V battery where a spare wheel would have lived in the past, and then buried it under assorted crap just to add to the fun. 
 

Dread to think what MB would charge to change it….

 

12V battery lurking lower left….apparently the official method involves lifting the 100kg HV battery (the big silver box on top).

 

I removed the diagonal brace visible here and the longitudinal crash bar that's hiding the +ve terminal to get at the thing. Was easy after that.

[p k]

Did you have to take the car to the dealers to have the car told its got a new battery ?

[corsechris]

16 hours ago, paul k said:

Did you have to take the car to the dealers to have the car told its got a new battery ?

I did wonder about that. I've got an iCarsoft MB2 diagnostics box for it that I'll plug in and see if it has any complaints...but it seems to be behaving OK

 

The only comments I've found so far talk about perhaps having to reset steering angle sensor, window limits, seats, that sort of stuff.  Pretty sure this car has enough backup in the supercap to hold that data.

[Stuart]

7 hours ago, paul k said:

Did you have to take the car to the dealers to have the car told its got a new battery ?

I read somewhere that if you keep a charger connected to the leads whilst you change the battery, it avoids the need for this. Seems logical but I have no idea why a new battery needs programming in anyway 

[corsechris]

There seems to be loads of FUD on this topic. One I read was that if you don’t reset ‘something’, the car will overcharge the new battery and it can catch fire. That fails the smell test straight away for me. If the car learns battery capacity, it will have learned that the old battery has reduced capacity. Installing a new one with original increased capacity could only result in undercharging, not overcharging….and even that notion is questionable, charge state is determined by battery voltage, so why not simply measure that?

 

I’ll keep digging, just out of interest really. 

[Man On The Clapham Omnibus]

9 hours ago, Stuart said:

I read somewhere that if you keep a charger connected to the leads whilst you change the battery, it avoids the need for this. Seems logical but I have no idea why a new battery needs programming in anyway 

I'd be a bit cautious about having a charger connected without the smoothing effect of the battery. Chargers can be very 'noisy' in electrical terms. My Z3 instrument cluster failed when I had a charger on a very flat battery and I unwisely switched on the ignition to check for the radio code being required. It lost all instruments bar the speedo and required a new coding plug. A second battery connected to an 'always live' cigar lighter socket or similar would be safer. Remember, though, that the leads from the battery you're changing will be live.

[corsechris]

In the past when changing batteries and wanting to maintain power I’ve gone for the jump battery option. Knowing the MB has an aux battery I didn’t bother this time round.

 

I just found a video where some random bloke on the internet changed the battery on his W205 (not the hybrid) and he addressed the question of any ‘reset’ being required. He said he contacted his MB dealer and they were unambiguous - nothing needed after a battery swap.

 

So, that’s conclusive then, ‘cos some bloke on the internet said it

 

I’ll stick the diagnostic box on the car later just in case I come across something, but I really don’t think anything is needed - it makes no sense at all to me, unless one was calibrating the car to a set specification of battery from a list of options….but then they specify only 1 battery for it…so again, makes no sense.

 

No denying manufacturers do make extensive use of component coding though. Some of it I accept has a clear purpose, like say injectors of differing spec, but other things one hears about like having to code headlights for example. Really? How do they justify that?

 

 

Anyhoo, it hasn’t caught fire yet…..

[Jim RS]

All I've ever found changing batteries is sometimes defaulting to manufacturers settings. I'm interested in this as I have just bought a C hybrid and noticed the manic electrical install in the boot and with initial problems traced to a pattern windscreen on mine I'm keen to hear of any irregularities.

[corsechris]

Which car have you got @Jim RS? Mine is a 2016 C350e

 

Just went through all the menus and codes on mine with the iCarsoft. Found the same historic faults in a few systems that had been there before I swapped the battery and they all cleared OK.

 

Roof and windows have retained calibration, as has the steering.

 

As it happens, it had a new screen a few weeks back, but everything was fine after. It was a Pilkington item and apart from lacking the ‘signature’ of the OEM one, it looked identical in every detail. They calibrated the camera as well and all the systems that rely on that seem to be working as they should.

[jonjh1964]

I changed the battery on my S205 c220d and the dealer told me that there was no need to take it in for coding.  I've now got a C300e and not looking forward to replacing the any of the batteries, although is still under warranty for a good while yet.

[corsechris]

Recently saw the end of the 6 year warranty on the HV stuff on mine. It’s hard to be sure, but I reckon it’s lost roughly 25% of the battery capacity in that time. Not that they give any capacity warranty on hybrids anyway, just ‘failure’.

 

Dread to think what they’d charge for a new HV battery tbh. I did see a thread some time ago for one of their first hybrids that had something like a 1kWh pack and that was apparently £15k…..although it was their first attempt and it had cooling provided by an A/C system and was horribly complicated.

 

At least your C300e has a sensible 25kWh battery. Ours is only 6.3kWh.

[7Westfield]

From what I've heard, the reprogramming after a battery change is more of a BMW thing

 

[Jim RS]

3 hours ago, corsechris said:

Which car have you got @Jim RS? Mine is a 2016 C350e

 

Just went through all the menus and codes on mine with the iCarsoft. Found the same historic faults in a few systems that had been there before I swapped the battery and they all cleared OK.

 

Roof and windows have retained calibration, as has the steering.

 

As it happens, it had a new screen a few weeks back, but everything was fine after. It was a Pilkington item and apart from lacking the ‘signature’ of the OEM one, it looked identical in every detail. They calibrated the camera as well and all the systems that rely on that seem to be working as they should.

Same as C350e, bought it with 3 years warranty so screen issue was covered.  MB dealer found problems as most of the safety devices had turned off. Has taken since November to get one of the cameras being off the road since end of December, only just got back. Also had issues with opening all the windows on its own but garage has reset all errors and updated system so that a few extra features are now showing.

From what I can understand the replacement screen was ok for basic models but did not support the extra safety features, I think this was the reason the last owner got rid. MB dealer was quoting silly money for OEM screen plus camera although health check was fair.

[corsechris]

I have a strong feeling I'll be selling mine this year. It's in perfect condition and very low miles, so hopefully I'll get a half-decent price for it when the time comes. No idea what to replace it with though. Vickie fancies the Audi E-Tron GT. Gulp.

 

Fault-wise, the only thing I've had is failed door handle LEDs - apparently they are pretty much guaranteed to fail on any model that has them. I've done both nearside ones so far. Easy enough job, just a bit fiddly. MB quoted £300 labour to replace 1. I politely declined....