W211 SBC battery help

[BAZ-500SL]

Ello guys just needed some help, these SBC batteries are they rechargeable or once they finished you need a need a new one, also ABS sensor fault, mechanic reacons once battery fitted other faults may clear to ? Any ideas

 

[mersum1es]

Eh... it is 'regular' VRLA technology battery, based on AGM structure. Car charges it automatically if it detect low voltage of the aux battery. Yes, you can charge it by battery charger (but since it is AGM you should have proper charger to get it full, old school charger will charge it but leaves it a bit short). And AGMs can fail like any acid-lead battery, at some point they cannot remain charge or receive it. Since they are sealed you cannot put more electrolyte inside like in old school batteries, but it wouldn't save always even them...

Low main battery voltage causes odd electrical gremlins all over the car but I doubt that your sensor or reluctor ring is truly faulty.

 

[Alps]

I assume you mean the small consumer battery? for the sake of £90 just change is.

SBC is the braking system pump and reservoir.

 

[BAZ-500SL]

Lol yeah the small battery, the garage I used said SBC battery lol sorry for the confusion, so it's best to just get a new one than messing about with it, plus I only have a old school charger so shouldn't really try messing about with it, I have ran the car for 30-45 minutes and let it stand on drive running for 3-4 hours but still the battery warning is on the dash my first thought was the main big battery in the boot but now it's been to garage he said it's the small one

 

[whitenemesis]

As the small auxiliary battery only comes into use if the big system battery get low on charge I doubt it would bring up a dashboard message.

Leaving the car idling for hours will not recharge the battery, it needs higher revs to do that, a good run for an hour or so. Are you sure your alternator is 100%? It's not uncommon for the reg pack to fail.

 

[John]

As the small auxiliary battery only comes into use if the big system battery get low on charge

I thought they ran in parallel?

 

[mersum1es]

I thought they ran in parallel?

Nope they are isolated via relay, aux is charged via main circuit if voltage low and only once during ignition is started, aux is connected to main circuit if main circuit voltage fails.

 

[AMGeed]

The Aux battery supplied by MB is a lead acid one too, not an AGM.
It was £72 just over a year ago.

 

[BAZ-500SL]

Had a volt tester on the small battery and put a fully charged big battery on it, still giving a battery fault in dash, the small battery is giving out a reading near 14v, still confused why if the small battery still has a good voltage but still the battery warning light is showing, car starts up ok I know the battery was dead so after a jump start the car was left running and now turns over fine so alternator may be ok, ? Also does the small battery be the same across the w211 range regardless of engine size as I might pinch one of a mate just to test it out or would it end up giving his motor gremlins lol