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Discussion Starter #1
Hi all, I've recently had a new battery fitted (under warranty) and because my regular commute is less than 100 miles a week on slow roads I'm investing in a trickle charger to give it an occasional top up. There are some power heavy features on these cars and initially I was a little shocked that the original battery lasted less than 3 yrs but then until this happened it never occurred to me that between the electric tailgate,often used with engine off,air con always on etc the battery probably rarely got anywhere near a fully charged state. On top of all that I am now on lockdown and the car isn't going anywhere.
I have ordered a NOCO 5 charger because its got good reviews and was just a a little bit cheaper than the CTEK ones which get equally good reviews. Never had one of these before so I was wondering what others opinions/experiences might be with them.
For future reference and something to look out for, the first indication I had that anything was wrong with the battery was the stop/start system became inop. The green light on the switch was on ok but the light on the dash never changed from amber to green even after a 300 mile round trip to south Devon.
 

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Try turning the AC off and you will see a miraculous change as the stop start kicks in.

I bought a AMG GLA 45 in November and even harangued the dealer about it and read the whole handbook on the system. Now the warmer weather is here the start stop works after about a mile and a half. In the dank midwinter I did a 100 mile run and it never gave a hint of working. Mines just had its “B” Service and they found nothing wrong with it. I have to say I don’t commute and it’s just used as a dump run car and a knock about, so mine gets perhaps less usage than yours.

It gets run in lockdown to the big Tesco but I turn the S/S off so that it doesn’t drain too much and AC off too. On the battery chargers I’ve used an Optimate 3 on every motorbike I’ve had for over 10 years. They are worth their weight in gold and “Harry’s Garage” (a YouTube fav) recommends the C Tek. Whatever you buy will undoubtably do the job.

Good luck with it.
 

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Auxiliary Battery

Hi Phil. I've got a 16 Reg GLA 220d 4Matic which has stood in my garage doing nothing during lock-down. I have charged the battery under the bonnet with a CTEK 5A charger. No problems as I'm pretty sure that this is the same as the approved Merc one for which they charge about twice the price!. I recently took the car on about a 10 mile drive and the green start/stop light didn't go green at all. I've done some research and it seems that there are quite a few criteria that need to be met for the stop/start system to be enabled.

One of these is that the Auxiliary Battery (behind the passenger foot-well carpet in my car) needs to be fully charged. This battery is only charged when the engine is running so doesn't get charged with the main battery during its external charge. I'm currently looking into a way of charging this battery from an external charger. Need to be careful as it is only a small battery. Probably need to use the motorcycle program on the charger.

It will probably take a fairly long run to fully charge the battery whilst driving. It's main function seems to be to supply the vehicle electronics during cold starting and stop/start/HOLD operation to prevent any volt-drops or spikes getting into the electronics. I understand that some Mercs use a "big" capacitor rather than a battery to perform this function ? Hope this helps.
 

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Hi Barry,

Funnily enough since the lockdown eased (I won’t say ended) I took the AMG on a south coast run along to Shoreham and then back along the A272. After about a 120 mile round trip the the start/stop light came back on. Result!

I knew there was a separate battery, but I did think it was up against the firewall in the engine bay? When I bought mine back in November last year it hadn’t been run greatly. 2,500 miles from new in 18 months. Now that was a second hand bargain! I actually took it back to the dealer and complained about it not working. They listened with that sigh that told me I wasn’t the first to complain. But it was winter and all the lights etc were on all the time. But again a few good long runs and it returns to normal.

Once it’s up to good charge and I’m using it normally it will actually kick in after about a mile and half. The engines not fully warm but the battery has enough beef after having long runs to top it up.

I was going to take the motorbike out today, but it’s just started raining. **** I’ll have to take the car for a spin instead. just topping the battery up Boris - honest.

Take care and enjoy the cheap fuel while it’s still low. Silly note: the GLA45 has to have the expensive petrol 99 Octane. The buggers never told me that when I bought it...

Cheers,

Phil B
 
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