1. MotorhomeFun The best Motorhome Club in the World
     
    Register to remove adverts Register Here

    Welcome to Motorhome Fun

    MotorhomeFun is a large community of motorhome and touring enthusiasts. Our website is the busiest of its kind. It serves as a meeting place for thousands of members who share their knowledge of motorhomes and travel, as well as arrange rallies in the UK, Europe and beyond.

    It's easy to join us and takes just a minute

batteries double charging

Discussion in 'TECH/MECH GENERAL' started by lou020, Feb 5, 2013.

  1. lou020

    lou020 Funster

    Joined:
    Oct 5, 2010
    Messages:
    256
    Likes Received:
    101
    Location:
    huddersfield
    another battery question,

    i leave the mh on hook up at home all the time which is charging the leisure battery

    i also have the engine battery coupled to a ctek battery maintainer/charger which is on all the time on hook up.
    i have noticed in the past the in line 25amp fuse from the engine battery to the on board fuse panel,(i presume) has melted the plastic surround of the fuse,it has never blown the fuse
    i have changed this fuse 3 times in the last 2 years.

    i was wondering if it was possible for the leisure battery to be getting 2 lots of charge,1 from the ctek + 1 from hook up, and overheating the fuse.
    there is 2 wires coming from engine battery, i presume 1 is for fridge and the other is the charge to the leisure battery, both are fused with 25 amp fuses, and it only melts the one.

    the fuses are the cheapo type, hard clear plastic.

    cheers Lou
     
  2. FULL TIMER

    FULL TIMER Funster

    Joined:
    May 31, 2012
    Messages:
    712
    Likes Received:
    592
    Location:
    NORWICH
    it is possible that the voltage going into your engine battery could be high enough to trigger the split charge relay therefore linking the two batteries, I had this happen with a durite self sensing split charger when I connected a sterling battery charger (capable of charging 3 separate battery banks independently) to my vehicle battery and the leisure batteries. might be worth taking the fuses out if you want to have both batteries on charge at the same time with two separate chargers, or maybe temporarily run a couple of wires from you leisure battery to the engine battery pos - pos , neg - neg and just have the habitation charger on.
     
  3. lou020

    lou020 Funster

    Joined:
    Oct 5, 2010
    Messages:
    256
    Likes Received:
    101
    Location:
    huddersfield
    Chere's fulltimer, l was thinking of taking the fuse out whilst on hook up.
     
  4. eddievanbitz

    eddievanbitz Trader - Funster

    Joined:
    Oct 4, 2007
    Messages:
    2,182
    Likes Received:
    4,058
    Location:
    Taunton Somerset
    You dont need to. On your motorhome the split charge relay is not voltage sensing.

    When the engine starts, the feed to your alternator warning light (on the dash) is used to energise a relay which puts the batteries in parallel (joins them together)

    A simulteaneous charge will not cause that fuse to blow. Not only that the CTek charger is clever enough to sense when there is no need for it to work.

    A bit like having the engine running on a sunny day, both the alternator and the solar panel regulator would cause the same problem. In reaity one of them (normally the solar regulator) would shut down as it would know that it is not needed.

    The reason that the fuse is blowing is when you go away off hook up and use your leisure battery , when you drive home you have a fully charged engine battery and a flat leisure battery. You start the engine and the batteries are in parallel (joined together) and the batteries try to balance and "pop" goes the fuse.

    Very common after a flat engine battery as well the other way around after a jump start.

    Removing the fuse when at home will have no effect. The only solution is to either live with it and keep an eye on things or replace the wire with a heavier guage add a 100amp relay and uprate the fuse and fuse holder to say 120amps. Or invest in a Battery to Battery charger that will resolve such issues as this.

    Hope that this helps

    Eddie
     
    2 people like this.
  5. FULL TIMER

    FULL TIMER Funster

    Joined:
    May 31, 2012
    Messages:
    712
    Likes Received:
    592
    Location:
    NORWICH
    bearing in mind that it would seem that your vehicle doesn't have a self sensing relay I agree with everything Eddie has said,
     
    2 people like this.
  6. pappajohn

    pappajohn Funster

    Joined:
    Aug 26, 2007
    Messages:
    24,161
    Likes Received:
    7,951
    Location:
    scarborough, nth yorks
    also, dump the cheap fuses....nothing but trouble.

    i used to use the ones from £ shops....50 or 100 assorted fuses for a quid...constantly either melting or 'invisible' blowing. (blowing right at the end where you cant see the break)

    cant see how they can source materials for that sort of money each, never mind manufacturing and packaging costs on top...quality has to suffer.
     
    1 person likes this.
  7. lou020

    lou020 Funster

    Joined:
    Oct 5, 2010
    Messages:
    256
    Likes Received:
    101
    Location:
    huddersfield
    Thanks for the replys, I think i will try a better quality fuse.

    It has never blown the fuse it just try's to melt the casing, the 25amp fuse is clear (ish) but it turns the plastic milky and expands,
    the cable is about 6mm and i wonder if the fuse holder is not capable of carrying the current.
    the fuse holder is the type with ordinary spade ends and the fuse slots in the top.

    i fitted a new fuse(cheapo) tuesday and i will monitor it whilst the mh is parked up.:Eeek:

    I will invest in quality fuses also. soon
    Lou
     
  8. eddievanbitz

    eddievanbitz Trader - Funster

    Joined:
    Oct 4, 2007
    Messages:
    2,182
    Likes Received:
    4,058
    Location:
    Taunton Somerset
    The fact that the fuse isn't blowing means it is nothing to do with the quality of the fuse.

    It is melting as your transferring too much current creating heat.

    Eddie
     
  9. pappajohn

    pappajohn Funster

    Joined:
    Aug 26, 2007
    Messages:
    24,161
    Likes Received:
    7,951
    Location:
    scarborough, nth yorks
    Sorry Eddie but if the fuse is rated at 25amps then it should be capable of carrying 25amps without melting....pointing to cheap Chinese plastic

    if its carrying more than 25amps then it should blow...which again points to cheap chinese fuses.

    the low price of these fuses relates to the poor quality
     
  10. eddievanbitz

    eddievanbitz Trader - Funster

    Joined:
    Oct 4, 2007
    Messages:
    2,182
    Likes Received:
    4,058
    Location:
    Taunton Somerset
    6 mm cable and melting fuses is indicative of too much current. Bring the load up slowly and the fuse will carry a greater load and generate heat. It is a weekly problem that our workshops see.

    The OP can change as many fuses as he wants, he has a fundamental problem, otherwise the original fuse wouldn't have blown.:Eeek:

    If the OP pm's me his address I will happily send him some good quality replacements and we spend tens of thousands of pounds on Ripaults fuses and terminals every year:Wink:

    Eddie
     
  11. lou020

    lou020 Funster

    Joined:
    Oct 5, 2010
    Messages:
    256
    Likes Received:
    101
    Location:
    huddersfield
    The fuse has never blown,, not with me anyway in 2 1/2 years.The fuses definitley are the pound shop type,(probably bought by my father from B&M).

    i will have a look in one of the volvo trucks and see if there is a spare quality one, otherwise i think i'll try a bigger fuse holder.
     
    Last edited: Feb 7, 2013
  12. pappajohn

    pappajohn Funster

    Joined:
    Aug 26, 2007
    Messages:
    24,161
    Likes Received:
    7,951
    Location:
    scarborough, nth yorks
    So quality does have a bearing then Eddie ! :BigGrin:
     
  13. lou020

    lou020 Funster

    Joined:
    Oct 5, 2010
    Messages:
    256
    Likes Received:
    101
    Location:
    huddersfield
    cheers eddie, i'll try and get some off one of our parts people first,if i get stuck i'll pm you.


    if it's any help the fuse is located about 6 inch from the battery.

    Now then another thing is one single 6mm wire comes off engine battery and then T's off into 2, each with a 25amp fuse.

    I think one is fridge and one is to leisure battery,only one melts the fuse, i need to find out which one go'es to where.
     
    Last edited: Feb 7, 2013
  14. Sidney

    Sidney Funster

    Joined:
    Jan 27, 2013
    Messages:
    744
    Likes Received:
    412
    Location:
    Stamford
    Yup too much current

    Yup too much current or to put it another way the fuse holder or crimp isn't man enough for the amps going through this point. Why? Heat is caused by resistance so deformation of the plastic indicates this area has a problem.

    Replacing the fuse holder with something designed for a much larger load will eliminate the problem. Replacing the fuse won't make any difference.

    I alway use heavy duty fuse holders, decent cables and gold battery connections (demanded by in-car stereo geeks) as a result I sleep easier at night.
     

Share This Page