RED BATTERY SIGN

[Gail Baxter]

Hi, I have a C180 sport 2007 and all of a sudden the red battery light icon has came on. Does this mean I need new battery or is it the alternator? How do I know? Can I still drive car just now?

 

[Blobcat]

I‘m guessing you’re not using it much... the battery will be less than 12.6v with engine off so needs charging or replacement. If you can, charge it - many of us use battery conditioners to keep them up to charge.

 

[Ron240]

When the red battery light comes on it is a warning that something is wrong with the charging system, which could be the battery itself or the alternator.
You need to have it investigated to find out exactly what the problem is, but it is not a good idea to drive the car with this light on.
If you are a member of any breakdown organisation then easiest thing to do is phone them and get them to check it.

 

[Blobcat]

When the red battery light comes on it is a warning that something is wrong witht he charging system, which could be the battery itself or the alternator.
You need to have it investigated to find out exactly what the problem is, but it is not a good idea to drive the car with this light on.
If you are a member of any breakdown organisation then easiest thing to do is phone them and get them to check it.

They’ll most likely say you’ll need a new battery then sell you whatever they have in their van. Up-selling batteries is one of breakdown services biggest money earners

 

[Woodleigh]

I spent a good 7 hours last week cleaning and valeting the car...running back & forth from the drive into the garage; doors opening and closing when I got this warning on the dash.
Took the car to the main dealer who tested it and it failed, so I asked them to install a new battery.
PS: The battery was 4 years old, but I blame lockdown short runs and Stop-Start. Also when I saw the warning rather than stat the engine I put it on CTEK for 24 hours.

 

[Ron240]

They’ll most likely say you’ll need a new battery then sell you whatever they have in their van. Up-selling batteries is one of breakdown services biggest money earners

You are such a pessimist Blobcat.
I would use my own judgement based on knowing how old the battery is. If it is more than at least 5 years then it is potentially more likely to be the issue, but it could just as easily be the alternator which will be more costly.
It should be a simple plug in and check to find out, and until this is done nobody will know for certain.

 

[LostKiwi]

If you have access to a voltmeter measure the voltage across the battery terminals engine off. If its 12.5 or less you need a new battery.
If it's above that start the engine and measure the battery voltage again. It should now be above 14v. If not wait a few minutes and recheck (leave engine running). If still not 14v or more your alternator has failed.

 

[Gail Baxter]

Thank you all. So, hopefully it’s just the battery. I wonder if I just order new battery from RAC. They won’t fit it if they do a check and it shows up that it’s not the battery.
The sign flashes up then disappears.
Am I doing more harm to car if I drive it??

 

[LostKiwi]

If it flashes up then disappears it's almost certainly the battery.
The risk you have is that it will fail to start the car when you're out.

 

[Gail Baxter]

If it flashes up then disappears it's almost certainly the battery.
The risk you have is that it will fail to start the car when you're out.

Ok, thank you.

 

[John77]

Hi I had this happen on mine as I have not been using it. Recharged the battery over night and it has not happened since, as I am using the car more. If you do need a new battery then a lot of people on here get them on line from Tayna, They are far cheaper for a quality battery. I am sure you could find someone to fit it for you. Maybe someone off here lives close. You do not need to be precise, but which town are you near?

 

[Woodleigh]

Ok, thank you.

Make sure you get the correct capacity for your car, mine is an 80Ah

 

[Gail Baxter]

Make sure you get the correct capacity for your car, mine is an 80Ah

Ok. Thanks.

 

[Gail Baxter]

Hi I had this happen on mine as I have not been using it. Recharged the battery over night and it has not happened since, as I am using the car more. If you do need a new battery then a lot of people on here get them on line from Tayna, They are far cheaper for a quality battery. I am sure you could find someone to fit it for you. Maybe someone off here lives close. You do not need to be precise, but which town are you near?

I am in Glasgow. I use my car all the time, so not sure why it has came up. I suppose the car battery is old - would that happen over time, that I need to renew battery?

Hi I had this happen on mine as I have not been using it. Recharged the battery over night and it has not happened since, as I am using the car more. If you do need a new battery then a lot of people on here get them on line from Tayna, They are far cheaper for a quality battery. I am sure you could find someone to fit it for you. Maybe someone off here lives close. You do not need to be precise, but which town are you near?

 

[Blobcat]

I am in Glasgow. I use my car all the time, so not sure why it has came up. I suppose the car battery is old - would that happen over time, that I need to renew battery?

Yes, batteries die over time. Unlikely yours is as old as your car, check the battery post and one will have a week and year number on it

 

[LostKiwi]

Yes, batteries die over time. Unlikely yours is as old as your car, check the battery post and one will have a week and year number on it

It could be that old. The one in my 2001 E Class was the original when I changed it year before last!

 

[Mr Hatt]

I changed out a battery on an Audi Q7 in March and it was the factory original making it over 10 years old, Audi Q7 batteries have to be coded using a BEM code to make the smart charging system know to go back to full charging again and all records of changes are in the system, these AGM type batts last realy well, even buying from Tayna it was £170 for Varta so just as well really

 

[Ron240]

I am in Glasgow. I use my car all the time, so not sure why it has came up. I suppose the car battery is old - would that happen over time, that I need to renew battery?

A fine city...I hail from a town 10 miles East.
An original battery should last around 5 years, but this can vary up or down depending on use.
I bought a 6 month old Ford Mondeo in 1997 and sold it in 2006 still using the original battery which started first time every time. In fact pretty much everything on that car was original apart from tyres.

 

[mioba]

post #7 thats it

 

[Ron240]

post #7 thats it

Well that's all very well...but unless you happen to be an electrician not many people have access to a voltmeter and know how to use it.