Red Battery icon (S211 E320Cdi)

[GavinP]

Had this appear a couple of times after not using car for a few days. Car starts fine - main battery showing 12.4V. If I try to apply SBC it says "not available" as I expected. If I switch off and re-start after driving 5-6 miles the "1 malfunction" message clears. Just checked front aux battery after a 40 mile trip and the reading is 11.48V.

Q1 - Does a battery charger charge main and auxiliary batteries?

Q2 - If not is it worth trying to charge the SBC battery or is that asking for trouble?
Q3 - Could it be anything other than a failing battery - car is 2005 and this is original SBC battery - main battery changed after 6½ years
Rgds

G

 

[190]

The first thing to say is that if the main battery voltage of 12.4 volts was measured in a no load condition i.e. with the car asleep then it is only 75 % charged at best and could be as low as 50% charged if it's an AGM battery.

I don't know if charging the main battery also charges the other. My guess would be it's entirely possible that it doesn't but you could always measure the voltage of one battery while charging the other which will answer the question.

If the 11.48 volts was measured immediately after using the car then it seems low but again voltage measurements as an indication of state of charge are only valid when there is no load or very little load which is not the case immediately after turning the engine off.

The starting point to make a diagnosis should be to fully charge both batteries and then see what happens.
Failing batteries don't necessarily show low voltage but the capacity and self discharge rate does mean they don't hold a charge very well when not being used.

 

[John]

211s suffer badly with even moderately lower than usual voltages - they seem to be quite sensitive to it.

Mine is coming up to 11 and I've replaced the alternator and both batteries within the last 3 years - and have since had getting on for a year without any issues.

The voltages you quote are a lot lower than the ones I had when my car gave me jip and did some right quirky things.

 

[GordonTarling]

I'd suggest that you fit a new aux battery - that voltage reading is too low. If that doesn't fix things, then have a reliable indy take a look at it.

 

[guydewdney]

Mine had this. Turned out to be a broken wire from the bcm (boot) to relay (under windscreen scuttle panel). After i replaced both batteries..... doh.....

Run engine. Check volatge of little battery. If it is not charging then check the wire from the relay to the bcm.

Is yours estate or saloon? My estate seven seater was a bastid to get to the bcm.

pm me if you want.

Guy