Mounting a B2B

Discussion in 'Tech/Mech General' started by SteveandDenise, Feb 8, 2014.

  1. SteveandDenise

    SteveandDenise Funster

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    Where do most people have their B2B mounted I have just bought a 50 amp b2b and had a look at fitting it I would like to have fitted it under the passenger seat but not quite enough room the only other option I seem to have is in with the two batteries under the lounge seats any one else got one fitted. I do want to keep the leads as short as possible it is a Fiat A Class:Smile:

    Steve
     
  2. jonandshell

    jonandshell Funster

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    As close to the batteries being charged as possible.:thumb:

    With your van having a CBE electrical system, don't forget to put in a heavy duty 5 pin relay in the original leisure battery positive cable to isolate the leisure batteries whilst being charged by the B2B.
    This should be switched by an ignition or D+ feed.
     
  3. SteveandDenise

    SteveandDenise Funster

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    batteries

    Thanks John.

    After having a further look I think I will mount the charger under the battery comparment in the double floor, so a very short run for leads, so that in its self is not a problem.

    Yes our van does have a CBE charging system, although I do know how a relay functions, what is the purpose of this ? I am assuming the charging system has a diode to stop any power going back to the charger. I suspect I could be wrong about that.

    Thanks

    Steve
     
  4. jonandshell

    jonandshell Funster

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    Hi Steve

    Consider this-

    When you start your engine, your B2B fires up and takes current from your starter battery, amplifies the voltage and directs this to your leisure battery.
    Simultaneously, the original split charge relay connects your starter battery positive to your leisure battery positive.
    This connects the output to the input of the B2B charger!
    Whilst this will not damage the B2B charger, it does prevent it from working correctly. Your batteries will never reach float voltage of 13.4 volts because 14.3 volts or so will be continually supplied by the original split charge system. This is not ideal for the long life of your batteries and they will not be subjected to the proper 4 step charge.
    Add to this the complication of 12 volt fridge operation and potential interference from a solar regulator, that expensive charger you have just fitted will never be able to determine accurately your leisure battery condition and won't charge them correctly!
    To combat this situation, you simply place a 5 pin relay in the positive lead from the leisure battery to the hab electrics. This is wired in such a way that when stationary, the battery is connected to the hab electrics. However, when the engine is started and the B2B is charging, the relay disconnects the leisure battery, leaving only the B2B connected to the leisure battery.
    Meanwhile your original split charge relay supplies your habitation electrics and fridge.

    Much easier done than explained, bit it will ensure your new B2B works correctly and your batteries last longer.

    NB, the voltages described above are relevant to the open lead acid setting on the charger.
     
  5. SteveandDenise

    SteveandDenise Funster

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    b2b

    I think I get the gist of that Jon, so when the engine is running the hab batteries are disconected via the relay so nothing in the van will run on 12v but the batteries get max amps/volts charge from b2b. Dose this also mean whilst driving the hab batteries are disconected ie so no 12v fridge etc. I think I will install right up to conection then have to seek some help from some one familiar with this type of set up:Doh:

    Thanks
    Steve
     
  6. Techno

    Techno Funster Life Member

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    [​IMG]
     
  7. jonandshell

    jonandshell Funster

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    No, the hab electrics and fridge are run by current supplied by the starter battery (and alternator) via the original split charge relay.
    You don't lose any of the original electrical systems functions with this setup.
     
  8. bungy

    bungy Funster

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    Would this still apply if you have a cbe parralel charging system like we haven in our van?

    Having checked out the leccy diagram for the van, and done some meter reading ours seem to work on voltage sensing relays and when the b2b is in action the hab batteries are isolated from the cbe, and fridge etc still work ok

    also, I thought it was best to have the b2b as close as possible to the van battery?
     
  9. SteveandDenise

    SteveandDenise Funster

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    b2b

    Now it is starting to make sence I had not realised the split charge would do that:thumb:
     
  10. jonandshell

    jonandshell Funster

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    Hi Bungy

    I reckon CBE must configure their DS300 panels for different manufacturers. Ours has a separate split charge relay. On the panels PCB, their is a gap where one would have been. Our previous CBE-equipped Elddis had the integrated split charge relay in that PCB location. Mind you, it was also configured for NCC compatibility! You had to remove a 2 amp fuse to keep the lights on!
    Does your leisure battery get floated at 13.4volts or does it keep getting alternator voltage?

    The reason I said the B2B is located closer to the leisure battery is voltage drop. The drop is more critical at the battery to be charged than the charging source due to the voltage amplification of the B2B.
     
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  11. haganap

    haganap Funster Life Member

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    I have mine located under the seat as per Techno's photo.

    I also went for the relay fitting options as it makes life much easier and gives satisfaction knowing your not being grumbled by any other parallel charging or fridge issues. Yes the fridge will still work without a relay but it's continuing to draw power and therefore effecting the recognized state of the batteries. That is not me saying that BTW that was mr Sterling, yet people still fit without the relay and have no problems, but I know the pros insist on fitting the relay.

    It's easy enough to do anyway, I done mine without even bending my back :Wink::Laughing:

    All whilst John watched to make sure it was going well :whistle:
    I then fitted another relay for my inverter whilst Bungy watched to make sure that was done properly too. :whistle:


    In other words I ffffiiiiiinggg hate Relay,s I simply can not seem to get my head around them.... But if you have a heart attack, you will be greatfull im there. :Cool:

    good luck what ever way you go...


    look at my ticker time John boy,,,, Im packed and ready to go :thumb:
     
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  12. bungy

    bungy Funster

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    And what an exerience that was:Rofl1:

    have you not had the call to go to sotchi yet?
     
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  13. bungy

    bungy Funster

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    Last time I checked it dropped back to 13.4 so assumed all was good:BigGrin:

    weve two relays, one for the hab and one for the van bat...the van bat one only kicks in when on 240 and the hab bat is full, and the hab one only kicks in when the van bat has reached its voltage, and as far as I can tell whilst the b2b is running it doesnt kick in...might just recheck that!!!

    I did try the relay route, but it played havoc with the hab electrics in that the fridge may or may not come on when on 12v, cbe panel may or may not come on...all very weird so took it out again and everything was fine..thats when I checked into how our van was wired up and discoverd the parralel charging and 2 relay setups workings....few nights studing the wiring diagram and testing everything with a mmeter:BigGrin:

    Ive also got a gert piece of wiggly string between the hab bat and the b2b...all 6m run of it, no voltage drop either as a result...so all good and its worked a treat for the last 18+months
     
  14. jb0371

    jb0371 Read Only Funster

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    I also fitted my b2b with a relay, for the afore mentioned problem, well I started to do it then went to work while Jon finished it off.:BigGrin:

    I also bought a smart charger connected to the engine battery, which then charges the engine battery while putting power through the sterling which in turn properly floats the traction batteries whilst the smart charger floats the engine one.

    Just checked the battery levels and dont why I bothered, both sysytems doing what there meant to.:thumb:
     
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  15. jonandshell

    jonandshell Funster

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    Can I offer an explanation for the fridge?

    On tickover, the Sterling puts such a load on the alternator that the alternator and cab battery voltage drops considerably.
    The fridge ECU sees the voltage is low and reverts to gas operation. At least that's what ours does when the A2B charger is sucking 90 amps and the alternator voltage is down to less then 13v!!:Eeek:
     
  16. bungy

    bungy Funster

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    Hadnt thought about that to be honest...makes sense
     
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