Confusion over W204 Stop/Start battery charging

Discussion in 'Electronics' started by nickpb, Jul 21, 2016.

  1. nickpb

    nickpb Hardcore MB Enthusiast

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    So this is probably going to end up being a dumb question, but I'll ask anyway.
    I have a 2012 W204 Estate with Start/Stop. Presumably this means that I have 2 batteries (i've only found the one in the boot at the moment - I can't see one under the bonnet yet).

    Anyhow, I am looking at getting a CTEK charger as I often don't do many miles and the Start/Stop doesn't stay active for long (which I presume is the battery).

    So the CT5 charger is designed specifically for Start/Stop batteries, but will I have to disconnect the battery before charging? I presume that the battery is on a completely different circuit from the 'main' battery, so connecting a charger to the battery points under the bonnet will charge only the 'main' battery?

    The CTEK CT5 is designed specifically for Start/Stop EFM/AGM bateries, so maybe I would be better off with a MXS 5 which will do all types?

    Any advice would be welcome please (along with tips to help find the 2nd battery). Thank you
     
  2. grober

    grober MB Club Veteran

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    The main battery is under the main heater airduct which is clipped to the front bulkhead [ other side from the steering column] .
     
  3. grober

    grober MB Club Veteran

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    I have a stop/start C200 W204 and have had it permanently hooked up to trickle charge in the garage for 3 years via an MSX 5 with no problems. No battery disconnect necessary
     
  4. OP
    OP
    nickpb

    nickpb Hardcore MB Enthusiast

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    Thanks Graeme, I appreciate your answers but there is still one thing I am not clear on.
    The handbook says to charge the battery 'using the jump-start connection point'. Will this charge both batteries, or will I need to connect direct to the stop/start battery to charge that one?
    Thanks,
    Nick
     
  5. grober

    grober MB Club Veteran

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    AFAIK the battery in the boot is a backup battery used to power the car's essential electronic systems ---usually made by FIAM part no A2115410001 its rated at 12v 12Ah 170 CCA as such it won't be used to start the car but will be linked into the main battery circuit by control circuitry. As such it will be automatically charged via the car's normal battery/alternator setup-- so all you need do is make sure the main battery is fully charged. If you ever experience any problems with it from age --straight replacement is the usual course of action.
     
  6. OP
    OP
    nickpb

    nickpb Hardcore MB Enthusiast

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    Ah right. Thanks for clearing that up. I always assumed that one was for the stop/start function alone. Now I see my mistake.
    Thanks Graeme.
     

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