Flat engine battery

Discussion in 'Tech/Mech General' started by jacken, Jan 13, 2009.

  1. jacken

    jacken Read Only Funster

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    Hi,

    went to start the motorhome to-day and nothing happened, dash lights came on and then dimmed when trying to start. I put a multimeer across the battery and it only showed 12.1 volts. I can't keep it on hook up as I have to keep it on the road. Can any-one confirm what it should read fully charged and read when flat. It is an 88 amp hour battery. I also checked the level of the cells and there was nothing showing so I had to put a whole litre of distilled water in. Is it time for a new battery? this is 5 years old now.

    ken
     
  2. Wildman

    Wildman Read Only Funster

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    13.8v -14v is fully charged, 12.6 is half charge and 12.1v is flat.

    Only time will tell if the battery will take a proper charge again as it has been left with a low level of electrolyte for some time. You could always take the battery indoors and leave on a float charge over the winter. Or add a solar panel to keep it topped up however unless you check it regularly and keep it topped up you will lose it. Good luck.
     
  3. Myfanwy

    Myfanwy Read Only Funster

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    Hi Ken

    Your engine battery is normally 13.8 volts when fully charged. I would suggest that if the battery is 5 years old then a new one is necessary. If you wish to test the battery this can only be done with a specific gravity meter. This is like a large syringe which you draw up the water and sulphuric acid mix and the balls float to tell you the state of the battery.

    I would suggest if you are leaving your vehicle on the road that you should purchase a small solar panel from Maplins (£9.99) which plugs in the cigarette lighter socket. This will not charge the battery but will stop it from discharging under its own steam.

    All batteries that are left will discharge themselves with time so this will stop that.

    Hope this is of use and help with your problem.

    Myfanwy's husband Alan
    :thumb::thumb::thumb:
     
  4. scotjimland

    scotjimland Funster Life Member

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    A fully charged battery won't read 13.8v unless it's just come off charge and certainly not after being charged by an alternator .. see chart .. but before taking a reading it must be left off charge for at least four hours..
    A fully charged battery will hold it's charge for many months, most problems arise with 'phantom' loads .. eg alarms, radios, etc which take tiny loads but ultimately flatten a battery

    [​IMG]
     
  5. Hycon

    Hycon Read Only Funster

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    Does electric hook up charge engine battery

    My engine battery was flat on my 1994 Hymer Fiat Ducato so I pluged in my electric hook up and expected it to charge the engine battery.It did not seem to charge it but was definitely charging the leisure battery.I had to charge it with a seperate battery charger and it was Ok. Is this how it should be or are some motorhomes wired to charge both batteries and others just to charge the leisure when on electric hook up.When the engine is running both batteries are charged.
     
  6. moandick

    moandick Read Only Funster

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    I can only really talk about US RVs as that is what I have - and yes, the engine charges both batteries but the hook-up only charges the house battery - unless you buy a modification to allow the hook-up to charge both.

    It usually causes a certain amount of consternation amongst RV owners when they find their engine battery dead after a few days on the hook-up. The problem is that there is always something applying a drain to the engine battery - the immobiliser, the engine management system etc., etc., etc. It may only be a small drain but it is always there - so most of us buy some form of supplemantary charger to keep the engine battery topped up. Whether it be a plug-in solar charger or a Halfords battery master is irrelevant - you generally need something extra!
     
    Last edited: Jan 13, 2009
  7. PeteH

    PeteH Funster

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    Simple things?

    Hi

    I use a Length of Substantial wire with a Croc; clip either end and a Fuse holder with 20Amp fuse in the line,conected between the "house" and "Chassis" batteries this allows the EHU to float the Chassis battery, the Fuse is for the day when I "forget" to disconect before starting as otherwise the Wire will try to take a full start charge and burn out!! (or burn something!!).


    Total cost ZILCH, as I had it all in the workshop!.

    (other more expensive devices are available!!!)

    Pete
     
    Last edited: Jan 13, 2009
  8. Tony Lee

    Tony Lee Read Only Funster

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    Either a very strange battery or very strange measurement technique.

    For OP. Correct technique for this condition is to just cover the plates, fully charge with a good three-stage charger and then top up to bottom of ring.

    A battery that has uncovered plates for a long time will suffer some permanent damage, but correct treatment in future may give a couple of years more satisfactory performance. If all cells were way down and you did check the levels say a month ago, then you may have a cheap taper charger and left it on for many days.
     
  9. Neckender

    Neckender Funster

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    My Fiat Trigano Tribute was the same, now I've fitted a van bitz battery master£58, it is a small electronic box with 3 wires, one to the positive to engine battery, one to positive on leisure battery, and one to earth. When on hook up now, it charges both batteries, if parked up and no hook up it shares the drain load between both batteries so vehicle battery lasts longer. since I brought this, CAK tanks do a similar device which is about £25.

    John.
     
  10. pappajohn

    pappajohn Funster Life Member

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    our kontiki can charge either battery on hookup BUT not at the same time.
    by flicking the 3 way rocker switch from 'cab' to 'house' or 'house' to 'cab' on the control panel it will charge or use either battery.

    flick it to the middle position and neither battery does anything but the hookup still powers the 12v side....i think anyway.:RollEyes:

    my solar panel kicks out around 7amps on a sunny day so a couple of hours will give my 'cab' battery enough charge for a 'warm weather' start....(wouldnt want to try that in winter though:Eeek:) and keeps the 'house' battery topped up no matter what the weather.
     
  11. Frankia

    Frankia Read Only Funster

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    If your Hymer has the schaudt electro block it is able to maintain a charge for both the house and engine batteries from a mains hook up. (as long as Hymer has wired it for that). The charge to the engine battery is only about half an amp though so it would not be much good for a totally flat battery. Which is possibly why you didn't notice the engine battery recovering.

    Again if it is a schaudt there is a connector on it for solar so you could attach a panel to it which would maintain both the house and starter batteries when the 'van is not being used for some time. n.b. it will only charge both batteries from solar when the solar panel is connected to the electroblock - most fditters of solars ignore the EBL and attach directly to the house batteries
     
  12. jacken

    jacken Read Only Funster

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    Thanks for the replies. Just going on to another point raised in one of the replies, I thought that on electric hook up both leisure and engine battery would be charged. Am I wrong? I have a control panel that has 1 meter and you press a button that shows engine battery and press again it shows leisure battery.

    ken
     
  13. sinbad1

    sinbad1 Deleted User

    Not sure wahat model you have ;but when the engine is running it will charge both engine and habitation batteries via a split charge relay system.

    To be honest if your battery is five years old its well past its sell by date. if there is a battery drain you can allways check this by switching everything off, then remove the positive battery connection , using a multimeter set to ohm's , connect the two leads of the meter red one to the battery, black one to the disconnected terminal. Any current drain will show on the meter. would suspect a new battery would solve your problem.
     
  14. GJH

    GJH Funster Life Member

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    In our Autoquest we have a switch which can be used to power the habitation electrics from either the leisure or vehicle battery but in our case EHU charges only the leisure battery.

    I left the switch on vehicle once by mistake and flattened the vehicle battery. Van was on EHU at the time.

    I subsequently bought a Tronic T4X charger as sold by Lidl (I think they've been selling them again recently and Aldi have been selling their version as well). At this time of year, if I think the vehicle battery might need a boost before we need to use the van, I use that overnight to give the vehicle battery a float charge.

    Graham
     
  15. scotjimland

    scotjimland Funster Life Member

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    disconnect the negative rather than positive ,it's much safer when doing a 'drain' check

    set the meter to DC mAmps, setting to Ohms will destroy the meter..
     
  16. sinbad1

    sinbad1 Deleted User

    Your right doh( got my undies wrapped over) perhapa diagram would have been better
    Mobile Solutions :: How To's : Measuring Stand-by Current Drain

    Not sure,if you would need to re enter the radio security code?
     
  17. scotjimland

    scotjimland Funster Life Member

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    No worries.. I have the same problem at times.. :Doh:

    nice link by the way.. :thumb:
     
  18. PeteH

    PeteH Funster

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    Battery Drain etc;

    Hi

    Don`t lose sight of the fact that Euro "charge" units ONLY maintain a battery. they are not designed to "boost" charge as under normal (EHU) conditions you would "cook" the battery.

    A good 3 stage battery charger is essential, disconect the battery when using as it IS possible to "bu***er" the electronics during the "bulk" charging phase, which CAN be as high 15volts.

    pete

    P.S I currently have a neighbours caravan battery on my 180amp boost charger, it was showing 9.4 volts when connected and is probably "dead", but I said I`d try it!!. the van had been in storage for over 6 weeks without charge. I suspect his "zig" unit is defective.

    p
     
  19. jacken

    jacken Read Only Funster

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    Just come back from a nice long drive to Hastings and back. Put a multimeter across the terminals and the reading was 12.85 volts. I will check it again to morrow night.

    ken
     
  20. Jaws

    Jaws Funster Life Member

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    Today I was called out on a bike job and the chap had a MH in the drive.. he said it was driving him nuts as the battery kept going flat.. After I got his bike sorted I wandered over and found a fairly big drain was taking place..
    Ten minutes later it was sussed. The relay that isolates the cab battery from the fridge had stuck on.. he had left the fridge on 12v and THAT was draining the battery.
    The reason I sussed it so quick was cos it is not the fist time I have seen it..
    Moral is just double check the fridge is REALLY off when you park up ! :Wink:
     
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