Battery charging question

Discussion in 'Motorhome Chat' started by browne4573, Oct 20, 2011.

  1. browne4573

    browne4573 Read Only Funster

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    If I want to use a maintenance charger over winter can I plug it in to vehicle battery and let split charge relay charge both batteries
     
  2. Phantom Menace

    Phantom Menace Read Only Funster

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    charger

    A maintenance charger usually has (smart technology) and will only effectively maintain one battery at a time, use 2 and be safe,or alternate one from battery to battery every week and remember leaving one in a discharged state for more than a month will usually be terminal! pardon the pun:Doh:
     
    Last edited: Oct 20, 2011
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  3. Snowbird

    Snowbird Funster Life Member

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    Am not sure if there would be enough voltage to open the relay. If your going to do that why not plug the camper in and check if the engine battery is charged from the on-board charger.
     
  4. pappajohn

    pappajohn Funster Life Member

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    i dont think that will work...

    the split charge relay is operated by the alternator, not the battery.

    the relay is usually triggered by the D terminal on the alternator as the engine starts
     
  5. browne4573

    browne4573 Read Only Funster

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    I haven't got an onboard charger, the split charge relay is plugged into the vehicle battery terminals. If I charge each battery separately using independant chargers will they interfere with each other as the batteries are connected. The split charge relay opens when the voltage is above a certain threshold.

    I am confused!
     
  6. Phantom Menace

    Phantom Menace Read Only Funster

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    split charging

    your road battery is charged by the altenator, when the voltage reaches a level the split charge relay operates and allows the altenator to charge the habitation battery, A maintenance charger probably wont achieve the voltage neccessary to operate the relay so with 2 chargers the relay wont allow them to interfere. If you are concerned you could always disconnect the habitation battery while charging. Dont forget to ventilate the area as the batteries give off hydrogen while being charged (very volatile)
     
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  7. pappajohn

    pappajohn Funster Life Member

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    if you have an (for example) 80ah engine battery and a 110ah leisure battery and a seperate charger for each battery and the relay does close then the chargers will see just one 190ah battery.
    each charger will see the same and try to charge them as one.

    i believe the relay closes at around 13.6v to 14v and its doubtful you will get 13.6v from a maintenance charger as it is only trickle charging most of the time.
     
  8. Snowbird

    Snowbird Funster Life Member

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    If you don't have an on board charger what charges your leisure battery and what happens when you plug into the mains.
     
  9. browne4573

    browne4573 Read Only Funster

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    The alternator charges both via the split charge system, I don't ever use sites with a hook up but over winter it'll be parked up outside my house so I can plug the maintenance charger in for when I am not using the van.

    The van is from 1985 so I don't think it ever had an onboard charger. I rewired the batteries through a split charge relay, I have a 55ah vehicle battery and a 100ah leisure battery.

    I had hoped that I could just leave the maintenance charger connected and then plug it in whenever I am parked ouside my house.
     
  10. pappajohn

    pappajohn Funster Life Member

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    one way round this is a flying lead between the two batteries and a single charger....a long wire with an insulated crocodile clip each end and clipped to the pos terminal of each battery.
    the two batteries will share a common earth, probably through the chassis.

    if you do this, then please fit a 10a fuse at BOTH ends of the flying lead,

    if the wire has a single fuse and is damaged and earthed then the fuse will blow but the other, unprotected, end will still be live and to earth possibly causing a fire.

    dont forget to remove the lead before starting the engine or the fuse(s) will blow
     
  11. browne4573

    browne4573 Read Only Funster

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    I think I'll just charge one at a time and then swap over every so often. Thanks everybody!
     
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