Inverter and EHU problems as fitted to our Hymer

Discussion in 'Tech/Mech General' started by Vennwood, Aug 14, 2015.

  1. Vennwood

    Vennwood Read Only Funster

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    I have recently bought a Hymer that has a Sterling Inverter fitted. It is plumbed directly into the main EHU supply via an automatic changeover switch. when on EHU the changeover selects external and when not available it looks for the inverter and if available it selects that. EHU and inverter both use the same 240 v circuit. So far so good. The problem arises when off grid and you switch on the inverter, the control panel thinks it has 240 v supply and powers all the sockets AND the on-board battery charger. So we have the leisure battery supplying the inverter that supplies the battery charger that then charges up the SAME BATTERIES that its getting its power from. To add insult to injury the control panel isn't smart enough to realise this and thinks its charging the batteries and so the AH reading goes UP and eventually says the batteries are fully charged however the battery voltage drops showing the correct level but this isn't accurate enough to give a clear picture of true battery state. Has anyone ever come across this and if so how did you get around it. Clearly it is wasting energy going around in circles and also the control panel is giving a false reading.
     
  2. Techno

    Techno Funster Life Member

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    Switch the charger off
     
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  3. Vennwood

    Vennwood Read Only Funster

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    I'm not sure its that easy to switch off as the charger is integrated into the whole fuse box/transformer unit. I'll have a closer look on the unit
     
  4. Techno

    Techno Funster Life Member

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    Presumably you have an electrobloc? so it may only be as simple as unplugging the mains lead into it or if it is fed via a circuit breaker switch that off
     
  5. Vennwood

    Vennwood Read Only Funster

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    Hi Andy,
    It is an Electrobloc EBL 99 and it's located outside in a locker behind the leisure battery. There isn't a separate battery charger switch but there is a power in plug but if I disconnect this I'm not sure what will or will not work. It wouldn't be a long term solution as I would have to go out every time I wanted to hook up so maybe an inline on/off switch just before the plug may be a solution.
     
  6. Techno

    Techno Funster Life Member

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    Unplugging it should only disconnect the charger, all the 12 volt circuits are still fed via the battery. Are you sure there isn't a switch already hidden somewhere?
     
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  7. Vennwood

    Vennwood Read Only Funster

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    No other switches - just a battery cut off switch that isolates the batteries. I think you are correct in that it only disconnects the charger so would it solve the problem if I put a switch on the positive 240 v lead to the Electrobloc and located it inside the camper? What do you think?
     
  8. Techno

    Techno Funster Life Member

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    Yes but I cannot imagine that whoever installed the Sterling did not consider this issue.

    @Don Quixote
     
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  9. Jaws

    Jaws Funster Life Member

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    The power lead that goes in to the Electrobloc EBL 99 needs to be disconnected from where ever it is at the moment and connected directly to the EHU feed in.
    That way it will only work when on hook up.. simples :)
     
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  10. TheCaller

    TheCaller Funster

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    With any luck, the EBL99 might be fed via an individual circuit breaker on the Mains Consumer Unit. If not, then follow Jaws' suggestion.
     
  11. Techno

    Techno Funster Life Member

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    The changeover should have been fitted in the radial that does the sockets not the hook up input
     
  12. TheCaller

    TheCaller Funster

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    Hymer + Sterling + auto changeover sounds like an after-market fitment to me.

    If you added up all the auto-electricians with M/H experience that you have ever seen recommended on this forum as competent at this level, I doubt you would run out of fingers. I know there will be more, but there are plenty I wouldn't let near it.
     
  13. Techno

    Techno Funster Life Member

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  14. Jaws

    Jaws Funster Life Member

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    yessss,, shoulda coulda... but we all know 90% of auto electricians who might be quite good with a car, aint got a bloody clue when it comes to motor homes and or mains wiring !
     
  15. Jaws

    Jaws Funster Life Member

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    What are the boxes you use Andy ? Project boxes are so damned expensive
     
  16. Vennwood

    Vennwood Read Only Funster

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    It was an after-market fit by a well known company

    Andy's diagram looks to be the answer however not knowing how or even where the autochanger over switch is fitted may take me some time to figure out. It appears (from the Hymer manual) that the Electrobloc was fitted under the passenger seat but as part of the after-market installation of the inverter it has been moved outside into the leisure battery locker and is now behind the battery. It appears that non of the wires are marked

    BTW the flexible tubing above is the fuel filler pipe.....
     

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    Last edited: Aug 14, 2015
  17. Vennwood

    Vennwood Read Only Funster

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    This would work as well but there are so many wires it looks like a bag of knitting gone wrong
     
  18. Techno

    Techno Funster Life Member

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    It's beaker from ASDA
    [​IMG]
     
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  19. dpsuk999

    dpsuk999 Funster

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    In my Dethleffs I have a normal household consumer unit with RCD's, 4 in total which allow me to isolate the EBL, sockets, air con unit and boiler so when I'm off hookup and using the inverter (which is wired into the consumer unit) I simply switch off the EBL, air con and boiler switches which then just leaves all my 240v sockets in the MH live.

    Switching the EBL off just means it's not charging the batteries or powering the fridge (as this would be on gas if wilding)

    So do you have a consumer unit somewhere allowing you to isolate different circuits?

    David
     
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  20. Vennwood

    Vennwood Read Only Funster

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    Hi David,

    I've recently bought the camper and still finding out things. Sadly most of the manuals etc. are missing. I'm kind of swamped with problems right now and the folks that should be able to help me out are on annual summer shut down until next week so its a case of seek and discover. If it ever stops raining I will be able to get out and trace a few things but I haven't found any RCD's yet.
     
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