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R230 Dual Battery On-board Electrical System

Discussion in 'Electrics, Vacuum, Ignition and ECU' started by whitenemesis, Jan 15, 2014.

  1. whitenemesis

    whitenemesis Senior Member

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    Your Mercedes:
    CLS55 AMG '05
    Front (Starter) Battery • Function:

    i) supplies electrical power for starter motor armature only
    ii) provides back up power to the system circuit

    Rear (Systems) Battery - Function:

    i) supplies electrical power for entire vehicle (incl. the starter solenoid)
    with the exception of the starter motor armature

    Everything you need to know about the R230 Dual Battery System
     
    Last edited: Mar 26, 2015
    rorywquin likes this.
  2. jmoser

    jmoser Guest

    Supremely useful - many thanks - especially re not using boot battery for jump-starting
     
  3. SH0X

    SH0X Senior Member

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    Joined:
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    Location:
    London UK
    Your Mercedes:
    SL500 R230
    Hi the link is not working?
     
  4. television

    television Always remembered RIP

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    Joined:
    Mar 14, 2005
    Location:
    Daventry
    Your Mercedes:
    2002 SL500, 216 CL500, all fully loaded
    This information is not valid for late cars. If you remove the rear battery the starter battery will take over, valid some time after 06-06.

    So if working on brakes, take special care on this one.
     
  5. imkaz

    imkaz Senior Member

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    Joined:
    Nov 12, 2013
    Location:
    United Kingdom
    Your Mercedes:
    R230 SL350
    I think the car can start and run just off the auxilary battery, as I did this without realising until I started the car the next morning and the red battery warning light came on, and noticed the starter/front battery was disconnected!
     
  6. wizzman

    wizzman Member

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    Location:
    Grimsby, NE Lincolnshire
    Your Mercedes:
    SL500 2002
    Can anybody recommend a quality trickle charger for the auxiliary battery ? I think my battery is on the way out and when I purchase a new one I would like to give it the best chance. This one is probably only two years old so not happy ! Overnight on a proper charger and its still charging at 5 amps in the morning. Any thoughts folks ?

    cheers

    Ian
     
  7. John Laidlaw

    John Laidlaw Senior Member

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    Location:
    Wirral
    Your Mercedes:
    W212 E63 ///AMG V8 Biturbo Volvo XC90 2018
    C Tek MXS 5.0 Ian, was on Amazon recently at £61 with free delivery on prime
    Loads of folks use these
    Aldi and Lidl do £15 specials occasionally, I have one which works fine but I know of others havent had good experience
     
  8. wizzman

    wizzman Member

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    Grimsby, NE Lincolnshire
    Your Mercedes:
    SL500 2002
    Thanks for that John.
     
  9. Denis O

    Denis O Active Member

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    Location:
    Weald of Kent
    The Aldi/Lidl ones have a major flaw. If you experience a power cut they revert to OFF until you change the mode back to charging. That's fine if you are on hand to re-set but if it happens, 1 week into you being away for 3 months, you come back to a flat battery.

    The C-Tek chargers revert to whatever mode they were in before the power cut.
     
  10. flowrider99

    flowrider99 Senior Member

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    Your Mercedes:
    SL500 (R230)
    The Aldi one i bought had a big flaw, as soon as i turned it on it went pop and never turned on again.
     
  11. John Laidlaw

    John Laidlaw Senior Member

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    Your Mercedes:
    W212 E63 ///AMG V8 Biturbo Volvo XC90 2018
    ^ There you go, 2 good reasons for the Ctek....prices have dropped too, they used to be over £100..
     
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  12. imkaz

    imkaz Senior Member

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    Location:
    United Kingdom
    Your Mercedes:
    R230 SL350
    As John Laidlow has said, I personally use the CTEK MXS 5.0 here: http://amzn.eu/dW37t1G It has worked perfectly, and has a function specifically designed for the AGM auxillary battery in the boot of the R230. I had a few problems with the battery being constantly low, I gave the battery a solid charge using the reconditioning feature, and battery has been golden since! Highly recommended.
     
  13. rpalmeida

    rpalmeida Forum Supporter Authorised Forum Supporter

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    Mercedes own charger is a CTEK one in disguise. So CTEK is the answer.
     
  14. Streetfighter1100

    Streetfighter1100 Senior Member

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    Location:
    London
    Your Mercedes:
    E350 Convertible
    Go to a motorcycle shop and get an Optimate charger.
    It checks the batteries state and charges as needed.
    It is also for sealed lead acid or gel batteries. The battery in the boot is sealed.
    These chargers are around £60.
    I have 4 of them, one for each bike.
     
  15. LostKiwi

    LostKiwi Senior Member

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    Location:
    Midlands / Charente-Maritime
    Your Mercedes:
    '93 500SL-32, '01 W210 Estate E240, 02 R230 SL500, 04 Smart Roadster Coupe
    A CTEK is cheaper. A bike sized one cant cope with a large car battery (they bike ones are rated to 50Ah). One big enough for the AGM in the 230 is over £110 whereas the CTEK MXS7.0 is under £100
     
  16. Streetfighter1100

    Streetfighter1100 Senior Member

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    London
    Your Mercedes:
    E350 Convertible
    I was not talking about charging the big car battery. The bike charger was for charging the small auxiliary battery.
     
  17. John Laidlaw

    John Laidlaw Senior Member

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    Your Mercedes:
    W212 E63 ///AMG V8 Biturbo Volvo XC90 2018
    Same though! Still not big enough
     
  18. ajlsl600

    ajlsl600 Senior Member

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    Location:
    france
    Your Mercedes:
    clk3202001,sl6002003 with everything,A class 170cdi auto
    ctek. never had issues with now,5 of them. 12 weeks away and starts straight of or would if i let it .i crank,stop, until oil lights go out ,then allow start.except where pre lube fitted.
     
  19. gassed up

    gassed up New Member

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    Jul 2, 2006
    Location:
    liverpool
    Your Mercedes:
    2011 C207 350CDI;2010 C207 350CDI sport;2010 SLK300;2004 C209 320;2000 C208 230K;
    Excellent link from the OP, thank you. Can anybody confirm the role of the B14 ambient temperature sensor in the charging system? I've got an SL500 with a starting/charging problem that is defying diagnosis, the one thing that is obvious is the ambient temp displayed on the dash is 49.5. I've ordered a new sensor as a starting point, has anybody encountered this before?
     
  20. LostKiwi

    LostKiwi Senior Member

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    '93 500SL-32, '01 W210 Estate E240, 02 R230 SL500, 04 Smart Roadster Coupe
    Temperature alters the charge rate of the battery and the cell voltage fully charged.
     

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