Battery Performance

[duncanh]

As my car is approaching its fifth birthday, I am starting to wonder about the condition of the battery.

Since I have been made aware of the "hidden menu" that shows battery voltage, I have been keeping my eye on it.

I use the car every day, 130 mile round trip commute each day Monday to Friday. Voltage in the morning is 12.3V. After starting it usually goes up to 14.6, dropping down to 14.2 after about 5 miles. It remains at about 14.1 or 14.2 for the rest of the journey.

I am sure that I read somewhere that the running voltage should not exceed 13.8. Does this mean that I have a problem?

Does anyone know if the MB reading is likely to be accurate?

Thanks

 

[Gollom]

Since I have been made aware of the "hidden menu" that shows battery voltage

Sorry I can't help with your actual question But........

Never heard of this before - standard or need Star?

 

[BlackC55]

14.2-14.6 is normal and the MB reading is probably very accurate. You have nothing to worry about.

The secret menu is really good as it allows you to completely turn off esp. If you turn it off with the usual button it only partialy turns it off. It allows some serious fun when on a track of course.

 

[dchaddah]

How can you access the secret menu?

 

[BTB 500]

I use the car every day, 130 mile round trip commute each day Monday to Friday. Voltage in the morning is 12.3V.

I would say the battery is on the way out, not a big surprise after 5 years. You are doing plenty of mileage so it should be fully recharged every day - that would be around 12.7V. The plates start to suffer gradual damage ("sulphation") below 12.4V ... which equates to 75% charge. So 12.3V isn't good, unless something is draining a significant amount of power overnight (plenty of threads/posts on that).

But given the age I would suspect you'll need a new battery at some point in the not too distant future.

 

[BlackC55]

Its a secret......

 

[dchaddah]

Its a secret......

Now thats not very nice is it!

 

[duncanh]

Hidden menu

• Switch off ignition.
• Turn key to position 1
• Access the mileage screen
• Press reset button 3 times in quick succession

Voila! it should now show the battery voltage

Pressing the up arrow on the left of the steering wheel will show the other hidden menus

When you get to the one with the oil level, turn the key to position 2 and it will tell you how much oil is in your engine.

 

[Stratman]

A "Menu Sticky" thread sounds like it might be needed. How's about it mods?

Isn't there another one that allows you to alter the oil service intervals depending on the type of oil used?

 

[MangoMan]

I've found out how to tell if my battery is on the way out, well 2 ways actually; 1) On models fitted with the old Scorpion Alarms, the alarm will arm automatically, even if you are driving at the time, resulting in a lot of noise and the engine miss-firing, hazards flashing and general mayhem and embaresment! (sic)
2) The engine won't start........

 

[tikw2124]

Secret menu

Followed Duncanh's instruction but the mileage screen does not change. Is this menu only on certain models?

Any advice will be appreciated

 

[duncanh]

Hidden menu

I'm surprised it does not work for you. Your car is similar in many ways to mine (model, year, etc) just a different engine.

Are you sure you are following the instructions fully?

Sorry to be pedantic, but in case my earlier instructions were ambiguous:-

• Put in ignition key
• Turn to first position (position 1)
• Bring up the mileage screen on the trip computer (trip mileage and total mileage)
• Press the reset button (the one that you use to zero your trip mileage) three times in quick succession
• Voltage SHOULD be on the screen.

If not, sorry, I can't help.

I don't think it works on the latest W203s, but should work on yours.

Anyone else having problems?

p.s. I didn't use the car over the weekend, voltage was 12.6 on Friday night, 11.8V on Monday morning. It started OK. How low will the voltage need to be to give me problems?

 

[BTB 500]

I didn't use the car over the weekend, voltage was 12.6 on Friday night, 11.8V on Monday morning. It started OK. How low will the voltage need to be to give me problems?

The 'fully discharged' voltage for a 12V lead/acid battery is 11.9V, so if the reading you're getting is correct (I would personally want to verify that using a multi-meter across the battery terminals) you already have a big problem!

As already posted, either the battery is shot or you have something draining power while the vehicle is parked. Or your voltage display is wrong (less likely IMO).

 

[recycled]

What is your fear about batteries . If it does not start in the morning and the warning light is on it means your battery is on its way out.They are not that expensive anyway and the car is not likely to breakdown on the road due to a weak battery as the alternator is charging it.
If you are so scared then just buy a new one.

 

[Stratman]

The first symptom of the battery on the way out my late W202 had was the cruise control playing up!

 

[1998K]

I'm surprised it does not work for you. Your car is similar in many ways to mine (model, year, etc) just a different engine.

Are you sure you are following the instructions fully?

Sorry to be pedantic, but in case my earlier instructions were ambiguous:-

• Put in ignition key
• Turn to first position (position 1)
• Bring up the mileage screen on the trip computer (trip mileage and total mileage)
• Press the reset button (the one that you use to zero your trip mileage) three times in quick succession
• Voltage SHOULD be on the screen.

If not, sorry, I can't help.

I don't think it works on the latest W203s, but should work on yours.

Anyone else having problems?

p.s. I didn't use the car over the weekend, voltage was 12.6 on Friday night, 11.8V on Monday morning. It started OK. How low will the voltage need to be to give me problems?

I confirm that this "secret menù" work well on my W203 C270 year 2003

As far as voltage: mine after a w-end it's before starting the car, 12.2V (drop down to 11 11.5 during start engine procedure, few seconds I means), after during cruising it's about 14.8 14.9V.

this for your info

 

[duncanh]

What is your fear about batteries . If it does not start in the morning and the warning light is on it means your battery is on its way out.They are not that expensive anyway and the car is not likely to breakdown on the road due to a weak battery as the alternator is charging it.
If you are so scared then just buy a new one.

I am not afraid of buying a new battery. I just don't want to buy one unless I need one. I also don't want the car to fail to start.

Having seen no symptoms of a failing battery, other than a low voltage reading (which may not be accurate), I was only asking for advice.

I have now come to realise that my battery is probably on its last legs, and consequently will replace it soon.

If it does not start in the morning and the warning light is on it means your battery is on its way out.

I think that means you have left it too late!

 

[tikw2124]

Hi Duncan, followed instructions again, still no hidden menus. However, found battery condition via COMMAND, Infos menu. First thing this am Batt indicated 12.38v, during transit, indicated between 14.42 and 14.69. All appears fine.

Many thanks

 

[migabc]

...found battery condition via COMMAND, Infos menu.

Can you describe how to get into this menu?
I don't seem to have this option on my W211 COMAND APS.

 

[tikw2124]

1. Select 'SYS'
2. Then select 'AUX'
3. Press 'Mute', '1' and '3' (together) hold these in till the screen changes
4. Select 'configuration'
5. then select 'Infos'
the battery voltage and other info should now be displayed