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[Andy B]

The facelift cars clearly have it in a different place too... Early cars GL have it under the right front seat behind the battery... Just to help

Mine is as the YouTube I linked to 

[Raeturbo]

Can you reach the fuse coming from that battery and monitor it from there?

[Andy B]

Can you reach the fuse coming from that battery and monitor it from there?

Not sure .... I've not looked that hard, just noticed the battery when I removed the access cover.

I found a youtube clip that actually covered both batteries. The aux battery isn't even as big as I thought https://youtu.be/A9XaApSoAAw

[Lizzie Zoom]

This thread reminds me that I have to ask about the latest cars, like my daughter Grandland X, that has the function whereby the engine turns off if the car stops when still driving but halted by lights, traffic, etc.

In my day we were taught that every time you started the engine of a car, it took 15-20 minutes for the battery to have the power drained replaced.

With these modern cars why are flat batteries not happening everywhere, especially in the big cities with stop and go traffic?

[Raeturbo]

I would say it’s just going too far to please all the worriers, everything they try to squeeze down on now after a couple of decades, is just not working, hell you have to be an IT genius to work on these new cars now, I’ll never buy a new/newish car unless I had wads of dough.

[Andy B]

This thread reminds me that I have to ask about the latest cars, like my daughter Grandland X, that has the function whereby the engine turns off if the car stops when still driving but halted by lights, traffic, etc.

In my day we were taught that every time you started the engine of a car, it took 15-20 minutes for the battery to have the power drained replaced.

.....

It's called stop/start .... & there's a button somewhere to turn it off, but unfortunately you have to press to disable each & every time you get in the car.

With these modern cars why are flat batteries not happening everywhere, especially in the big cities with stop and go traffic?

They fit two batteries 
Seriously, they fit AGM batteries which cost an arm & a leg

[STEMO]

This thread reminds me that I have to ask about the latest cars, like my daughter Grandland X, that has the function whereby the engine turns off if the car stops when still driving but halted by lights, traffic, etc.

In my day we were taught that every time you started the engine of a car, it took 15-20 minutes for the battery to have the power drained replaced.

.....

It's called stop/start .... & there's a button somewhere to turn it off, but unfortunately you have to press to disable each & every time you get in the car.

With these modern cars why are flat batteries not happening everywhere, especially in the big cities with stop and go traffic?

They fit two batteries 
Seriously, they fit AGM batteries which cost an arm & a leg

Usually between £3-400.

[JasonH]

This thread reminds me that I have to ask about the latest cars, like my daughter Grandland X, that has the function whereby the engine turns off if the car stops when still driving but halted by lights, traffic, etc.

In my day we were taught that every time you started the engine of a car, it took 15-20 minutes for the battery to have the power drained replaced.

With these modern cars why are flat batteries not happening everywhere, especially in the big cities with stop and go traffic?

You are right but what actually happens is that the Stop/Start only works when the battery is fairly well charged. So once the battery drops to say 60% charge the Stop/Start will stop stopping if you follow me.

Once you've driven round enough to get the charge in the battery it'll resume Stop/Start. These cars often have regenerative braking so when you brake some of the braking is charging the battery rather than wearing out brake pads.

[Andy B]

  ....
 These cars often have regenerative braking so when you brake some of the braking is charging the battery rather than wearing out brake pads.

I think you're confusing with hybrid/electric cars 

[STEMO]

It's more like an 85% battery and very, very few have anything as fancy as regenerative braking. It's not just stop/start that stops working at 85%. On my astra heated seats will turn off, air con efficiency will reduce, etc., and mine doesn't even have stop/start.

[STEMO]

Well.....it has an ignition key, I suppose.

[Marks DTM Calib]

  ....
 These cars often have regenerative braking so when you brake some of the braking is charging the battery rather than wearing out brake pads.

I think you're confusing with hybrid/electric cars 

Nope, the alternators charge at a lower percentage of capacity, say 60%, then when braking, they wind the output upto 100% 

Its like a very mild hybrid system and does save some energy

[Auto Addict]

I was under the impression that you shouldn't charge a AMG Stop/Start battery with a 'normal' battery charger, you need one with a a Stop/Start switch.

You also need to charge each battery separately, the Aux. battery can be charged with a normal battery charger.

The Stop/Start function on the car will only work if the AMG battery is in tip top condition.

[Marks DTM Calib]

So lets consider the facts and remove the Mercedes bit 

The only truth is that the AGM battery tech is more sensitive to overcharging, in theory the float voltage needs to be a few hundred mV lower then for that of a standard Pb battery.

However, the chargers people have are very low current (I see 4A ish max being quoted) and on float they will be putting in, at best, 1/10th or less of this. So they wont be an issue and are not like the massive things on wheels we have at work. 

As for the secondary battery in Mercs, they are for aux systems and designed to be deep discharged (they are in simple terms a mini leisure battery), they only charge when the engine is running. So keep the main battery topped up by the jump start terminals (do NOT go straight to the battery terminals) and when the car is running next, it will top up the aux battery 

[Andy B]

So lets consider the facts and remove the Mercedes bit 

The only truth is that the AGM battery tech is more sensitive to overcharging, in theory the float voltage needs to be a few hundred mV lower then for that of a standard Pb battery.

However, the chargers people have are very low current (I see 4A ish max being quoted) and on float they will be putting in, at best, 1/10th or less of this. So they wont be an issue and are not like the massive things on wheels we have at work. 

As for the secondary battery in Mercs, they are for aux systems and designed to be deep discharged (they are in simple terms a mini leisure battery), they only charge when the engine is running. So keep the main battery topped up by the jump start terminals (do NOT go straight to the battery terminals) and when the car is running next, it will top up the aux battery

Thanks Mark 
I can't easily get to the starter battery anyway