[Smigger250]

To connect your CTEK leads to the battery was the cover easy to remove? I have noticed there is a positive only smaller cover....not sure why? Thanks

 

[Macgd016]

To connect your CTEK leads to the battery was the cover easy to remove? I have noticed there is a positive only smaller cover....not sure why? Thanks

I would check the maunal for instructions but I pushed the red cover to one side and connected the red +ve clip and connected the black clip to the brass nut by the wing, I believe that this is the -ve ground point.

 

[Macgd016]

I asked MB CS a couple of questions the other day and they have just got back to me:

1. How long should an A Class battery stay charged if the car is unused A. Don't know

2. What is the minimum voltage at which the car will start. A Don't know

3. Does the car enter a standby state when its critical voltage is reached A Don't know.

4. If the battery drains in three weeks or less how would you keep it charged at say an airport A. Use a trickle charger.

I pointed out that there is no power at car parks which flummoxed him

The chap apologised that he didn't have the technical knowledge to answer these questions but would pass it to the technical dept but didn't think they would know how long a car could be parked with a fully charged battery, I pointed out that it was a fairly easy calculation, Amp Hours of the battery divided by amps per hour used, not hard really

 

[Peter55]

I made some interesting observations recently. Ever since I've owned my A250 (7 months) the battery gauge has shown 12+ volts when driving but 14+ volts when coasting (this is when the alternator is giving a higher voltage). From what I had read about these new fangle dangle charging systems this seemed to be right. Recently I got the battery voltage critical warning so charged the battery with my CTEK over night, now I have 14.1 to 14.5 volts under normal driving and up to 14.9 volts when coasting so it will be interesting to see what happens when (if) I do a bit of stop/start town driving again.

Mine was showing partially charged on the app, just taken it for a 30 minute 14 mile run
The display showed 14.8 up 14.9 coasting.
Now shows charged on app, but I know if I do a 1 mile Tesco run it will be back to Partially Charged, going to have to go the long way round!
I’ve previously left it and other cars at airport car parks for 15 days and never had a battery problem, but I would advise leaving the handbrake off

 

[Macgd016]

I've left my cars at Heathrow for three weeks or more in the past without problems but as my battery went down to critical in 2.5 weeks I'm trying to get a bit more info out of MB, after all they designed and built the thing so they should be the best people to ask

 

[tylers24877]

I've had the battery replaced under warranty 2 months ago, however today I'm getting the critical battery level warning on the app.

 

[johnPadgo]

I received this email from MB yesterday, “Supporting you during this time”,what does this mean :- you don’t need to charge the 12 volt battery, is that the 2nd battery?

If you are not using your car regularly, we recommend starting the engine and letting it run for a period of at least 15 minutes every two weeks. It is important to allow the engine to run for this long so the battery can charge properly. Be sure that your car is outside when the engine is running and don’t leave it unattended.​

Charge (SOC) should ideally be maintained at 50% and shouldn’t drop below 30%. You don’t need to charge the 12-volt battery as this is supported through charging of the High Voltage (HV) Battery.​

 

[Macgd016]

I received this email from MB yesterday, “Supporting you during this time”,what does this mean :- you don’t need to charge the 12 volt battery, is that the 2nd battery?

If you are not using your car regularly, we recommend starting the engine and letting it run for a period of at least 15 minutes every two weeks. It is important to allow the engine to run for this long so the battery can charge properly. Be sure that your car is outside when the engine is running and don’t leave it unattended.​

Charge (SOC) should ideally be maintained at 50% and shouldn’t drop below 30%. You don’t need to charge the 12-volt battery as this is supported through charging of the High Voltage (HV) Battery.​

I also received this email, I have no idea what it means, are they are talking about an EV battery?

 

[Marco68]

I also received this email, I have no idea what it means, are they are talking about an EV battery?

I got the e mail too. Hadn't used the car for 3 weeks and the app was saying that the battery was charged. So today I did as the e mail suggested and started the car and let it tick over for 20 minutes. The app now says that the battery is partially charged!!!! Does that mean that MB's advice is wrong?

 

[Macgd016]

Not sure about wrong but it's not good advice in my view

Firstly you shouldn't start a car and let it idle, especially when it's been standing for a while, you want oil pressure as quickly as possible so 2000 rpm would be good for a few seconds

Second letting it idle will fill the exhaust with wet gasses so you need to take it for a run so the exhaust gets hot and burns the wet off.

Third is similar to 2, if the engine doesn't get nice and hot the block will have condensation which will be absorbed by the oil.

 

[First and last]

Im getting same on both apps ‘Battery Partially Charged’. Happened today.

Getting the alert on Mercedes Me that my battery is low, probably because I haven’t been out on a long trip for a couple of weeks
Did a short one and noticed stop/start was working
Guess it is a case of too much information

A lot of people seem to have similar problems with variations. Similar but different...Love to know how many are out there...

our case is we have an A250... we started having significant battery drain one month after purchase.. it has had a new battery installed by the dealer.. but still has significant battery drain.. we have used ”stand by” function and switched of most of the electrics (wifi, Bluetooth, internal external lighting etc) but no impact..still lose power.. based on stand by function MB estimate a full battery should provide at least 22-23 weeks (yes 22-23 weeks) stand by power.. we have carried out our own extensive tests and our conclusion is that even in standby you only have about 1 week of power before battery is probably dead....

Haven,t tested it until battery is dead as can not afford a dead or damaged battery during the current crisis

We maybe being mischievous but the lack of support even acknowledgement of the problem .. indicates MB has stuffed it’s implemention of MBUX and its extensive functionality by not being able to manage battery drain.. and they are being quiet about the problem because they have new models rolling out with MBUX and are avoiding bad press..

If they just made Standby mode work it, would be brilliant... but ignoring the problem as we have experienced is not the way to go...

MBUX is great in our eyes as is the car.. but it fails simply because of battery drain...it maybe just our car and we are a one off ..but we suggest you test your car.. after 6, 7 or 8 days in isolation see if you get a battery critical message on the dash.. also try and engage standby and see how many weeks battery power you have...

For us 1 week battery power is inconvenient even dangerous in an emergency and if it is a normal condition we would not have bought the car... constantly placing a charger on car that should not require it, to cover for a design flaw is just not good enough Especially for a luxury car.. and a car for daily driving not a super high performance car that spends most of it life in a garage..

 

[Ben&Sandy]

I have an 2019 A220 in England and it does not have "Standby Mode".
I have left the car unused for 3 weeks without problem, I then had the doors open cleaning it when it complained the "Starter Battery" was low.

 

[Marco68]

Not sure about wrong but it's not good advice in my view

Firstly you shouldn't start a car and let it idle, especially when it's been standing for a while, you want oil pressure as quickly as possible so 2000 rpm would be good for a few seconds

Second letting it idle will fill the exhaust with wet gasses so you need to take it for a run so the exhaust gets hot and burns the wet off.

Third is similar to 2, if the engine doesn't get nice and hot the block will have condensation which will be absorbed by the oil.

Then why are Mercedes suggesting the above? They have repeated it on their Instagram page today. I commented the same as above and they directed me to the Mercedes Me team as they said that the partially charged indication on the app may be a fault with the app!

 

[Maxspencer99]

Then why are Mercedes suggesting the above? They have repeated it on their Instagram page today. I commented the same as above and they directed me to the Mercedes Me team as they said that the partially charged indication on the app may be a fault with the app!

I wonder how reliable the app battery status really is. Been trying to drive the car once a week - after using it to deliver odds and sods to my parents - just to keep the battery in decent working order. On Monday the app said ‘charged’ before I set off and ‘partially charged’ after a 30 min drive. Go figure?

 

[Macgd016]

Then why are Mercedes suggesting the above?

It could be that they have had lots of emails from A Class owners saying that their batteries are going critical ?. They cant suggest they go for a drive as that is forbidden, if they suggest a trickle charger some people might ask for MB to cover the cost of this as their batteries have drained in just 2 to 3 weeks. Other than that the only thing they can suggest is letting the engine idle in the drive way which as I have said before is not good for the engine or exhaust and I would be surprised if 15 minute would charge the battery very much in any case.

The only practical solution is a trickle charger which is what I am doing but as its normally connected to my summer car in the garage its a bit of a pain having to swap it over, that and having a mains lead outside where if it rains (remember rain ) it could cause further problems

 

[Smigger250]

Ditto...my A250 is connected to the CTEK this afternoon.

 

[relax24]

Haven't touched the car since end of March and got the alert saying my starter battery was critical

Guess I better go and turn the car on and leave it running for a bit!

 

[Pm001]

Haven't touched the car since end of March and got the alert saying my starter battery was critical

Guess I better go and turn the car on and leave it running for a bit!

I give mine a quick 15 minute run just once a week, seems to be enough.

 

[Macgd016]

I had an interesting conversation with a MB tech today, it seems that if you report this sort of problem they are able to check which module is causing the battery drain, in my case they think it was the Interiour CAN bus waking up and staying on for to long, so they reset it and crossed their fingers 🤣

Its wonderful that they can trace whats waking up when the cars locked, just a shame they can't do anything other than reset the module, update the software and hope for the best. But they are giving me a new battery so that might help

 

[First and last]

I had an interesting conversation with a MB tech today, it seems that if you report this sort of problem they are able to check which module is causing the battery drain, in my case they think it was the Interiour CAN bus waking up and staying on for to long, so they reset it and crossed their fingers 🤣

Its wonderful that they can trace whats waking up when the cars locked, just a shame they can't do anything other than reset the module, update the software and hope for the best. But they are giving me a new battery so that might help

I had a thought the other day,

if the Stand-by function ( not available on all cars eg UK) can read the SOC (StatusOf Charge) and it also appears that irrespective of whether you have the stand-by function or not, you can display your voltage along with Power (KW), Turbo Boost, Torque (NM) why not display SOC on the dashboard.

This way we can minimise somewhat, the parking anxiety we get when leaving the car in the garage. We can thence determine when to put the car on a charger, just like when we look at the fuel gauge to determine when to put petrol in the car.

As it is we do not know the SOC at any stage and repeated small distance drives maybe depleting the battery reducing its ability to remain locked up in the garage for any length of time.

This simply seems a common sense feature for a car that has a heavy load on its battery and a smart alternator that charges intermittently. It simply gives some degree of certainty and control back to the owner.

The only spanned in the works I can see is that the SOC value/module/calculation is not built into cars without the Stand-by function ( I.e in the UK), and this would be shame, as the ability to display the SOC would otherwise mainly be a software update to a digital display.

The software merely needs to read the value and display it. After all we can see the voltage in real time, we can see if and when the alternator is charging the battery, the car has a warning message when the battery charge is critical, so why then can’t we see the SOC on the dashboard.

Maybe I don’t know What is what, but I really would like something to help me plan when to put the car on a charger and not simply because it is critical, but rather let me decide when it is suitable time as part of my busy schedule. That is, when will the car will be in the garage for a day and a night let’s say, to give a good charge and make the effort of plugging and unplugging worthwhile.

Something to think about I guess.