Battery running too low?

Discussion in 'Motorhome Chat' started by Sam, Sep 17, 2009.

  1. Sam

    Sam Read Only Funster

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    Hi All,

    Tried to find an answer to this by doing a search on the forum but gave up after the 6th or so page.

    My MH has one leisure battery. When hooked up, it reads 14V. When freshly charged it reads about 12.1-12.3V. When a couple of lights (not LED) and the music is on for about 2-3 hours and some usage of the water pump, it goes down to around 11.2-11.5V.

    Question 1: Does this sound reasonable? My heating runs on gas.

    Question 2: To what voltage do I let it drop before I worry about damage to the battery?

    Question 3: Would running the car on idle for 30mins or so make a big difference? I am under the impression that the alternator does not produce any decent charge unless the engine runs at least 2000rpm

    Final question: How many batteries should I have If I want to be independent for at least 36 hours with lights, some music or TV for some of the time?

    Thanks lots in advance!
     
  2. savantuk

    savantuk Read Only Funster

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    It seems that your battery is dead:cry:

    A 12v battery, fully charged, should read around 12.7V, when not supported by the mains. Once it get's to around 12.3V, it's for all intents and purposes flat. 12V and below, means that the battery is beggared. If it's reading below 12V, it's quite likely that the plates are buckled, and sulphated, and no amount of charging will bring it back from the dead.

    I'm very much afraid, that if your volt meter is accurate, you'll need a new battery. There is not even any point in checking the electrolyte levels, and re-charging.

    The reason it reads 14.2V when on charge, is simply because that should be the maximum voltage whilst charging. As soon as the charger is disconnected, the voltage will drop very quickly, because th battery is unable to support a charge.

    Once you have fitted a new battery, it's worth swapping out any halogen or other incandescent bulbs for LED substitutes. You can run 9 or 10 of these for the same consumption as one halogen. Better yet, but a solar panel of 80 watts or more, and assuming that you don't use a 12v television, or other power hungry devices, you should be self sufficient for as long as you need. I've lasted 3 weeks, and never had the battery drop below 12.6V.
     
    Last edited: Sep 17, 2009
  3. JJ

    JJ Funster

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    I agree with Savantuk... you have the exact symtoms I struggled with for weeks... I replaced the leisure battery(s) with new and all running brilliantly now...

    JJ
     
  4. SC 05 OUT

    SC 05 OUT Funster

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    you have a defunct battery, it is no more, its gone to happy land of dead cells


    please buy another



    you know it makes s............
     
  5. vwalan

    vwalan Funster

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    hi sam , visit cornwall batteries at threemilestone industrial estate . probably the cheapest place in cornwall for batteries .
     
  6. Wildman

    Wildman Read Only Funster

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    dare I suggest it your battery is knackered and you need a new one.
     
  7. Tony Lee

    Tony Lee Read Only Funster

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    Sam, I see you have been MHing for a year so if your MH is also a year old, it might be worth reviewing your system and how the battery is treated to see if that has contributed to an early demise.
    If the battery is three or four years old then there may be no problem but otherwise just replacing the battery may lead you to be asking the same question in a year and that would be a waste of money.

    Practices that kill a battery quite quickly include never charging your battery up in the first place, using a cheap taper charger and leaving it connected for days, and running the battery almost dead flat and not charging it up immediately it does get discharged.
     
  8. Gonewiththewind

    Gonewiththewind Read Only Funster

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    Hope this helps
     
  9. Sam

    Sam Read Only Funster

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    Thanks for all the advise everyone very useful indeed. Alan, Thanks for the tip on where to source a cheap one :thumb:

    As I've only had this MH for a few weeks I suspect the battery was gone already when I got it...

    What size battery do you recommend I should get? more than one? The existing one is under the passenger seat. I guess I could fit another under the driver seat. Can I connect the second battery in line with the first one, or should it be a parallel connection to the charger?
     
  10. DESCO

    DESCO Read Only Funster

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    Hi Sam
    The obvious answer is as large as possible, with the batteries in parallel if you go for two.
    I would tend to see what you can fit in easily and take it from there. If you do decide to link two use thick wire to connect to avoid loss in cable with a fuse in the pos line to protect the wiring. You may find that you can get a larger one in the present location, would make life simpler. Depends on how you camp with EHO or without.


    Dave:thumb::thumb:
     
    Last edited: Sep 18, 2009
  11. Sam

    Sam Read Only Funster

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    Thank you Dave,

    Problem actually solved. The dealer I bought from was very happy to put a new one in :BigGrin:(I thought after the clutch he would not want to know...).
    He managed to fit a 110 replacing the 85 that was there before, so I'll see how that goes

    All the best
     
  12. Wildman

    Wildman Read Only Funster

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    It really depends on usage, but if you have room then the more the merrier, 110-120 amp/hr. If you have the room fit a matched pair and connect pos to pos -neg to neg. That would give you 110 or 120 amp hours of use. (you should never allow a battery to get lower than 50% charge).
     
  13. pappajohn

    pappajohn Funster Life Member

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