Electrical issues

[St3veP]

Hi all. Can anyone help?

I have a 2004 e270. Absolutely no issues with it until a couple of days ago. The red battery pic came up with consumer electrics not available and I lost heaters radio etc.

Checked the voltage of the front aux battery with engine off. 12.5.
Car starts with no issues at all but after about 10 secs the warning pic comes on again.
Checked the voltage of the rear battery engine off 12.4.
Now when I'm driving and sat idling the engine is surging. It's never done that before.
Volt meter shows no apparent charge at the aux battery with engine running and fluctuating charge at the rear between 12.4 and 13.8

I've spoken with the garage that does bits to complicated for me and they think it's the charging system and want to replace the alternator.
Idiot alert coming up.......Also there is a spy glass on top of the rear battery. Looking into it is clear. No colours of anything. I'm sure it's too check the battery state but how?

I know with this being a diesel is not the simplest of jobs and money is a real issue for me.
My only driving is short runs off about 6 miles rack way to work. Start at 7 so lights on automatically when driving in.

Any other ideas guys? BCM, Relay?

 

[daveenty]

I'm no expert on electrics, or much else come to that, but the first thing I'd be doing would be to put it on a charger to make sure the battery is OK.

Your pattern of driving won't help matters, maybe worth taking it out for a good blast round when you get the chance just to put the battery back to something like, as a 6 mile run with loads of electrical stuff running won't help it at all.

 

[PobodY]

To me, that fluctuating charge with the engine running is too low. - It should be ~14.4v from the alternator.

As to whether it's the alternator not providing the voltage, or the battery working like capacitor (which they do when they're completely dead), it's hard to tell.

From memory that little window in the battery should be green for a fully-charged healthy battery. - If it's clear and bright, the battery is low on electrolyte. If it's sort of dark and murky (possibly looking black), that's low on charge but plenty of electrolyte.
It does vary by design and manufacturer though.

 

[St3veP]

Took her for a long run. After about 15 miles I got my electrics back. Stopped for a quick cuppa them after a few seconds lost then again. Then after about another 40 miles battery alternator warning then brake warning and then lost everything. Got recovered back.
Any further ideas guys bcm? Or alternator route?

 

[David404]

By chance I've had exactly the same problem this week on my 2009 E320 (W211). Driving home from work red battery warning light came up on dash. When i got home I checked the battery voltage 12.6v. started engine battery voltage went up to 13.something.

Charged battery to 100% with Ctek. (Lidl have an automatic charger on offer this week at about £15 which is well liked)

Next morning battery voltage was down to 12.28v

Drive to work (20miles) check battery voltage 12.08v

Took car into workshop the fitted alternator and it now seems fine.

For info the Alternator parts cost was £342 inc VAT but they will have fitted Bosch or OEM equivalent, somebody like Euro Car Parts may well supply a cheaper alternative.

I would however always recommend cleaning terminals on both batteries and fully charging both with a smart charger to 100%. Batteries in a poor state of health/charge can produce all sorts of odd behavior/error messages before diving in with expensive alternator replacement.

Hope this helps, hope you get sorted.

 

[St3veP]

By chance I've had exactly the same problem this week on my 2009 E320 (W211). Driving home from work red battery warning light came up on dash. When i got home I checked the battery voltage 12.6v. started engine battery voltage went up to 13.something.

Charged battery to 100% with Ctek. (Lidl have an automatic charger on offer this week at about £15 which is well liked)

Next morning battery voltage was down to 12.28v

Drive to work (20miles) check battery voltage 12.08v

Took car into workshop the fitted alternator and it now seems fine.




For info the Alternator parts cost was £342 inc VAT but they will have fitted Bosch or OEM equivalent, somebody like Euro Car Parts may well supply a cheaper alternative.

I would however always recommend cleaning terminals on both batteries and fully charging both with a smart charger to 100%. Batteries in a poor state of health/charge can produce all sorts of odd behavior/error messages before diving in with expensive alternator replacement.

Hope this helps, hope you get sorted.

Thanks. Well new aux battery ordered and rear battery on full charge. Let's see if this approach works first.