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[Andy B]

I'll ask here .... better chance of a reply rather than the MB's forum standard reply of take it to a dealer/indie. 

If I wanted to use a CTek on my ML due to it standing more than normal, does anyone know if the auxiliary battery in the 'boot' get charged if I just connect the charger to the jumper connections under the bonnet? (starter battery lives under the driver's seat) Access to the aux battery requires dismantling of the boot liner/carpet.
I'm not really sure what the aux battery is for .... some suggest it's something to do with stop/start. 

[Doctor Gollum]

It provides power whilst the engine is off, saving the big battery for the big job

[Field Marshal Dr. Opti]

My CLS 500 had a second motorcycle sized battery. Never quite sure of it's purpose.

[Doctor Gollum]

It provides power whilst the engine is off, saving the big battery for the big job

[Andy B]

My CLS 500 had a second motorcycle sized battery. Never quite sure of it's purpose.

That's what mine is like, though you can only just about see it if you remove the cover that accesses the back of the rear lights.
Not sure how long it would provide power .... 

[Andy B]

so ..... does the aux battery charge from the jumper points? 

[Field Marshal Dr. Opti]

My CLS 500 had a second motorcycle sized battery. Never quite sure of it's purpose.

That's what mine is like, though you can only just about see it if you remove the cover that accesses the back of the rear lights.
Not sure how long it would provide power .... 

The Germans think it fun to make them difficult to get at.

[Doctor Gollum]

so ..... does the aux battery charge from the jumper points? 

Christ no AIUI, it keeps the climate control ticking over in REST mode and powers the radio. So apart from a couple of coolant pumps and a low blower speed, it doesn't actually need alot of power.

If I remember, I will have a look and see what WIS has to say about it.

[Raeturbo]

Well if that’s the case what keeps the little battery charged then?  If you can get a multimeter on it check it when you have the other one charging.

[Andy B]

so ..... does the aux battery charge from the jumper points? 

Christ no AIUI, it keeps the climate control ticking over in REST mode and powers the radio. So apart from a couple of coolant pumps and a low blower speed, it doesn't actually need alot of power.

If I remember, I will have a look and see what WIS has to say about it.

I didn't put it very well. Jumper points are obviously connected directly to main battery ..... 

[Andy B]

Well if that’s the case what keeps the little battery charged then?  If you can get a multimeter on it check it when you have the other one charging.

That's what I was trying to avoid 

https://www.youtube.com/watch?v=ATjTFgx2Yzs 

[Andy B]

I'll just use the car every other week 

[Doctor Gollum]

https://forums.mbclub.co.uk/threads/auxiliary-battery.200744/

[Andy B]

https://forums.mbclub.co.uk/threads/auxiliary-battery.200744/

I've seen that before, but some Mercs seem to have some kind of large capacitor instead and the web has conflicting info

[Doctor Gollum]

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

[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 

[Marks DTM Calib]

The modern cars have coulomb counting to get an estimate of battery charge capacity, if you go directly to the terminals, it confuses the system (it bypasses the current monitoring) and then you get a whole host of weirdness

[Andy B]

The modern cars have coulomb counting to get an estimate of battery charge capacity, if you go directly to the terminals, it confuses the system (it bypasses the current monitoring) and then you get a whole host of weirdness

No wonder you can't (easily) work on new cars ... 

[Doctor Gollum]

Newer X5s blow the board in the rear SAM if you jump the battery

[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.

.....

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

Ah, thanks Andy

[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.

.....

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.

What!  Bloody hell!

Just imagine being an owner of one of those cars in the future when the batteries fail.  I moan about paying £70+ for replacements. 

[Field Marshal Dr. Opti]

I always disable the stop/start facility on the Indian.

Used it for a month to see if it made any difference to MPG. Nope....SFA.

Gimmick.

[Andy B]

I always disable the stop/start facility on the Indian.

Used it for a month to see if it made any difference to MPG. Nope....SFA.

Gimmick.

stop/start is more to do with reducing emissions 

[Field Marshal Dr. Opti]

I always disable the stop/start facility on the Indian.

Used it for a month to see if it made any difference to MPG. Nope....SFA.

Gimmick.

stop/start is more to do with reducing emissions 

Yes, Mr Beanz. But many people think they will get an extra 10 MPG while saving the planet.

[STEMO]

I always disable the stop/start facility on the Indian.

Used it for a month to see if it made any difference to MPG. Nope....SFA.

Gimmick.

stop/start is more to do with reducing emissions 

Yes, Mr Beanz. But many people think they will get an extra 10 MPG while saving the planet.

There's a very easy way to increase mpg........diesel 

[Field Marshal Dr. Opti]

I always disable the stop/start facility on the Indian.

Used it for a month to see if it made any difference to MPG. Nope....SFA.

Gimmick.

stop/start is more to do with reducing emissions 

Yes, Mr Beanz. But many people think they will get an extra 10 MPG while saving the planet.

There's a very easy way to increase mpg........diesel 

Don't start.

[Andy B]

I always disable the stop/start facility on the Indian.

Used it for a month to see if it made any difference to MPG. Nope....SFA.

Gimmick.

stop/start is more to do with reducing emissions 

Yes, Mr Beanz. But many people think they will get an extra 10 MPG while saving the planet.

There's a very easy way to increase mpg........diesel 

You've not driven my Merc then ..... 

[Andy B]

I always disable the stop/start facility on the Indian.

Used it for a month to see if it made any difference to MPG. Nope....SFA.

Gimmick.

stop/start is more to do with reducing emissions 

Yes, Mr Beanz. But many people think they will get an extra 10 MPG while saving the planet.

I disable my stop/start each time too .... 

[Field Marshal Dr. Opti]

I always disable the stop/start facility on the Indian.

Used it for a month to see if it made any difference to MPG. Nope....SFA.

Gimmick.

stop/start is more to do with reducing emissions 

Yes, Mr Beanz. But many people think they will get an extra 10 MPG while saving the planet.

There's a very easy way to increase mpg........diesel 

Tunnie was always banging on about 70 MPG and more from his derv Passat.

What does the brown  Merc van manage?

[Doctor Gollum]

I always disable the stop/start facility on the Indian.

Used it for a month to see if it made any difference to MPG. Nope....SFA.

Gimmick.

stop/start is more to do with reducing emissions 

Yes, Mr Beanz. But many people think they will get an extra 10 MPG while saving the planet.

There's a very easy way to increase mpg........diesel 

Tunnie was always banging on about 70 MPG and more from his derv Passat.

What does the brown  Merc van manage?

Probably 5 mpg less than the silver Merc Mumsybus...

As for Tunnie, it is commonly acknowledged that he can't drive... as bourne out by his ongoing car choices

[STEMO]

I always disable the stop/start facility on the Indian.

Used it for a month to see if it made any difference to MPG. Nope....SFA.

Gimmick.

stop/start is more to do with reducing emissions 

Yes, Mr Beanz. But many people think they will get an extra 10 MPG while saving the planet.

There's a very easy way to increase mpg........diesel 

Tunnie was always banging on about 70 MPG and more from his derv Passat.

What does the brown  Merc van manage?

Probably 5 mpg less than the silver Merc Mumsybus...

As for Tunnie, it is commonly acknowledged that he can't drive... as bourne out by his ongoing car choices

What you driving at the moment, Al? 

[Doctor Gollum]

I always disable the stop/start facility on the Indian.

Used it for a month to see if it made any difference to MPG. Nope....SFA.

Gimmick.

stop/start is more to do with reducing emissions 

Yes, Mr Beanz. But many people think they will get an extra 10 MPG while saving the planet.

There's a very easy way to increase mpg........diesel 

Tunnie was always banging on about 70 MPG and more from his derv Passat.

What does the brown  Merc van manage?

Probably 5 mpg less than the silver Merc Mumsybus...

As for Tunnie, it is commonly acknowledged that he can't drive... as bourne out by his ongoing car choices

What you driving at the moment, Al? 

A borrowed BMW 330D. With indicators.

Hoping to get my virus riddled S Class up and running by the end of the month... parts permitting

[henryd]

Talking  of Tunnie,not heard from him in ages 

[Field Marshal Dr. Opti]

Talking  of Tunnie,not heard from him in ages 

Probably knee deep in soiled nappies.

[Andy B]

I always disable the stop/start facility on the Indian.

Used it for a month to see if it made any difference to MPG. Nope....SFA.

Gimmick.

stop/start is more to do with reducing emissions 

Yes, Mr Beanz. But many people think they will get an extra 10 MPG while saving the planet.

There's a very easy way to increase mpg........diesel 

Tunnie was always banging on about 70 MPG and more from his derv Passat.

What does the brown vermillion  Merc van manage?

Probably 5 mpg less than the silver Merc Mumsybus...

As for Tunnie, it is commonly acknowledged that he can't drive... as bourne out by his ongoing car choices

It's actually better than the R Class ... not by much though. I can see 30 when doing the 25 miles to work on a mix of roads but usually before the traffic starts.

[Doctor Gollum]

I guess the breezeblock styling is positively offset by better engine cooling as a result of not stuffing it back in the dashboard...

[TheBoy]

I'll ask here .... better chance of a reply rather than the MB's forum standard reply of take it to a dealer/indie. 

If I wanted to use a CTek on my ML due to it standing more than normal, does anyone know if the auxiliary battery in the 'boot' get charged if I just connect the charger to the jumper connections under the bonnet? (starter battery lives under the driver's seat) Access to the aux battery requires dismantling of the boot liner/carpet.
I'm not really sure what the aux battery is for .... some suggest it's something to do with stop/start. 

The small battery *should* be OK, but getting a bit of charge in it if its not being used wont harm at all.  Long term deep discharge will damage it still.

Main battery, given that the Ctek is at the best of times a woeful piece of shit, get it as near to the battery as possible, though taking the hhydrogen/spark issue seriously.  Additionally, it must be the other side of any battery monitoring system that modern cars have, so the monitor can see the electrical pixies going in, as well as going out.

[Andy B]

I'll ask here .... better chance of a reply rather than the MB's forum standard reply of take it to a dealer/indie. 

If I wanted to use a CTek on my ML due to it standing more than normal, does anyone know if the auxiliary battery in the 'boot' get charged if I just connect the charger to the jumper connections under the bonnet? (starter battery lives under the driver's seat) Access to the aux battery requires dismantling of the boot liner/carpet.
I'm not really sure what the aux battery is for .... some suggest it's something to do with stop/start. 

The small battery *should* be OK, but getting a bit of charge in it if its not being used wont harm at all.  Long term deep discharge will damage it still.

Main battery, given that the Ctek is at the best of times a woeful piece of shit, get it as near to the battery as possible, though taking the hhydrogen/spark issue seriously.  Additionally, it must be the other side of any battery monitoring system that modern cars have, so the monitor can see the electrical pixies going in, as well as going out.

I'm not sure I'd recognise it if I saw it, especially as access to the battery is 'restricted' 
Surely the jumper terminals would be the most convenient charge point & be other side of the monitoring gizmo 

[TheBoy]

I'll ask here .... better chance of a reply rather than the MB's forum standard reply of take it to a dealer/indie. 

If I wanted to use a CTek on my ML due to it standing more than normal, does anyone know if the auxiliary battery in the 'boot' get charged if I just connect the charger to the jumper connections under the bonnet? (starter battery lives under the driver's seat) Access to the aux battery requires dismantling of the boot liner/carpet.
I'm not really sure what the aux battery is for .... some suggest it's something to do with stop/start. 

The small battery *should* be OK, but getting a bit of charge in it if its not being used wont harm at all.  Long term deep discharge will damage it still.

Main battery, given that the Ctek is at the best of times a woeful piece of shit, get it as near to the battery as possible, though taking the hhydrogen/spark issue seriously.  Additionally, it must be the other side of any battery monitoring system that modern cars have, so the monitor can see the electrical pixies going in, as well as going out.

I'm not sure I'd recognise it if I saw it, especially as access to the battery is 'restricted' 
Surely the jumper terminals would be the most convenient charge point & be other side of the monitoring gizmo 

It may or may not be. Remember, this is a MB.

As for the Ctek, being a piece of junk, its essential its connected as close as possible to the battery as possible, and that's not the jumping points.

[Andy B]

....
As for the Ctek, being a piece of junk,  .....

I have two of them. One permanently connected to my bike (no idea why as I'm unlikely to use it again) and the other frequently connected to the Smart Roadster .... neither have had problems starting them. 

[Doctor Gollum]

Don't forget that TB thinks everything is shite... 

[johnnydog]

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.

What!  Bloody hell!

Just imagine being an owner of one of those cars in the future when the batteries fail.  I moan about paying £70+ for replacements. 

I think that figure could be possibly a little misleading....
I recently had to replace an AGM battery on a 2015 4.2 V8 Audi. Audi quoted near enough £250 for a genuine replacement, but with discount came to a figure of near £150. Didn't even consider getting a price elsewhere.
Although you do have to factor the hours labour on top to programme the new battery to the car, otherwise some of the electrical systems will not function properly. That ideally needs to be a main dealer job - wouldn't really trust the word of a back street 'just fit it - it'll be reet' battery supplier.

[STEMO]

Here's one for my astra. I don't doubt you could get it cheaper, but the figures I quoted were ball park

https://www.eurocarparts.com/p/exide-agm-115-car-battery-80ah-3-year-guarantee-444779030

[Andy B]

Here's one for my astra. I don't doubt you could get it cheaper, but the figures I quoted were ball park

https://www.eurocarparts.com/p/exide-agm-115-car-battery-80ah-3-year-guarantee-444779030

According to that site, your battery is a little more expensive than mine would be

[TheBoy]

....
As for the Ctek, being a piece of junk,  .....

I have two of them. One permanently connected to my bike (no idea why as I'm unlikely to use it again) and the other frequently connected to the Smart Roadster .... neither have had problems starting them. 

Ask tunnie how good my last 2 Cteks for the bike were .  He had to call me a couple of hours before we ever went out for a ride, give me time to use a proper charger

[TheBoy]

Don't forget that TB thinks everything is shite... 

Maybe unfairly, but I expect a single task product to do the task it claims to reasonably well.  If it can't do that task it claims is its primary use, then in my book, its shite.

[Marks DTM Calib]

Here's one for my astra. I don't doubt you could get it cheaper, but the figures I quoted were ball park

https://www.eurocarparts.com/p/exide-agm-115-car-battery-80ah-3-year-guarantee-444779030

EuroidiotParts at their robbing best there.

Even Halfords is half the price, without trade discount, and a five year warranty (£113.60 on Trade)

https://www.halfords.com/motoring/batteries/car-batteries/halfords-115agm-start%2Fstop-agm-12v-car-battery-5-year-guarantee-710859.html

[henryd]

Here's one for my astra. I don't doubt you could get it cheaper, but the figures I quoted were ball park

https://www.eurocarparts.com/p/exide-agm-115-car-battery-80ah-3-year-guarantee-444779030

On my trade acc with euro that comes in at 160 + vat

[STEMO]

Here's one for my astra. I don't doubt you could get it cheaper, but the figures I quoted were ball park

https://www.eurocarparts.com/p/exide-agm-115-car-battery-80ah-3-year-guarantee-444779030

On my trade acc with euro that comes in at 160 + vat

I know, Henry. I just posted it for effect so my original post didn't look stupid 

[ronnyd]

Here's one for my astra. I don't doubt you could get it cheaper, but the figures I quoted were ball park

https://www.eurocarparts.com/p/exide-agm-115-car-battery-80ah-3-year-guarantee-444779030

On my trade acc with euro that comes in at 160 + vat

I know, Henry. I just posted it for effect so my original post didn't look stupid 

You sure it's worked?