Split-charge relay - More than 50amps can flow between the engine battery and your leisure battery, so always get a relay that is rated at 50amps or more.   Preferably 75 or 100 amps.  Many relays sold on eBay are 30amps and designed for systems on cars, and not for connecting heavy duty batteries.

http://www.iem-services.co.uk/showdetails.asp?id=1169

Comments (206)

  • jacket's picture

    Hi Darren
    I have just purchased a van fitted with a Sterling battery to battery charger connected to a leisure battery which in turn is connected to the inverter, this is separate to the 12v split charge system on the van, so in fact I have two leisure batteries. Would it be possible to go from the inverter straight into the hook up socket on the outside of the van as though I was on mains power? I do a lot of wild camping & the fan on the combi boiler soon flattens the leisure battery, if I turned the onboard battery charger off would this set up (via inverter) still run the combi fan? Many thanks

    Feb 13, 2014
  • Darren's picture

    Hi

    I'm not sure I understand what you mean.
    I'm not sure why you would want to connect the inverter to the main hookup.
    Can you give a drawing explaining what you have?

    Feb 13, 2014
  • jacket's picture

    Hi Darren
    I'll try & explain better I always over explain I think. I have the normal split charge system & the battery is located behind my driving seat. Some distance away I also have an extra leisure battery fitted in the rear of my van charged via a Sterling battery to battery charger, this is connected to a 2500w inverter, can I go from the inverter (ie plug a modified lead with a household plug into the 3 pin socket on the inverter) then put the other end of the lead into the side of the camper (the blue 16amp inlet)?
    So when the 1st battery is getting flat I could use the 2nd one as though I was on "hook up" Hope this makes sense. Many thanks - Steve

    Feb 13, 2014
  • Darren's picture

    Hi Steve

    Yes, in theory this would work. I would be careful to not run anything with a high load on this configuration. But should work fine.

    Feb 14, 2014
  • jacket's picture

    Thanks Darren much appreciated

    Feb 14, 2014
  • jacket's picture

    Hi Darren
    Just another question regarding above. If I am plugged in using the inverter as a hook up so to speak, if I turn off the battery charger will I still be feeding the 12v side of the system as well. Thanks in advance - Steve

    Feb 14, 2014
  • Darren's picture

    Hi Steve

    Hard to say without seeing it, but I would say yes. In fact I would recommend turning off battery chargers when using this configuration. It will save your battery power.

    Feb 15, 2014
  • ChrisC's picture

    Hi Darren, i really need your help and cant find the answer anywhere.

    I need to know if I parallel link 3x 140amp leisure batteries ( i need ALOT of power! :) can i use a 140amp splitter relay charger? This is my first time trying to convert a van but I'm worried that by parallel linking the 3 batteries (420amp) thats its to much for the relay! or does it not effect it like that??

    Really appreciate your advice mate!

    thanks

    Chris

    Feb 10, 2014
  • Darren's picture

    Hi Chris

    Yes the 140amp split relay will be fine. I have a similar setup on my van and it works great. Do fit fuses between the batteries. Try a MegaFuse, 100amp should be fine.
    Even if the batteries we are completely flat the relay wont pass 420 amps. The engine has a regulator which will take care of this, which you are borrowing via the engine battery.

    Cheers

    Darren

    Feb 11, 2014
  • ChrisC's picture

    Thanks Darren, much appreciated, have fitted it all , just order higher fuses like you said, van is nearly fully converted and ready for the road, leave on Monday! thanks mate!!

    Feb 18, 2014
  • Neo 's picture

    Hi,

    Can anyone pls help. Just converted Renault Master and put in a 2000w pure sine inverter. The inverter is connected direct to two 110aH Leisure Batteries and from the inverter there are two sockets and the malaga heater with 230v option.

    I have not used the heater yet and only run an ipod player but still the inverter starts beeping and cuts off?? The van is stationary and nothing else running but still the inverter starts beeping.

    I have a solar panel feeding the two batteries and the indicator light shows half to full charge most days??

    Any advice very welcome
    Thanks

    neil

    Jul 24, 2013
  • Darren's picture

    Hi Neil

    The inverter would normally beep if there is not enough power in the batteries to function. But the iPod charger will use very little power, and it sounds like you have enough power in the batteries.
    Does it do the same if the engine is running? Assuming you have a split-charge relay which charged the leisure batteries from the engine when running.

    Jul 25, 2013
  • Gerald's picture

    Hi I have been asked to look at the electrics on a VW camper and have found that the electric hook up is connected into a garage consumer unit to run most of the lights and sockets ok so far, but also connected into the consumer unit is an inverter, This is totally unsafe as when the mains is hooked up 240v can flow back into the inverter but more importantly if the plug is removed from the inverter there is mains voltage at the terminals of the plug. My question is does a change over switch exist that can be fitted to make this situation safe, I would appreciate any help many thanks. Gerald

    Jul 16, 2013
  • Blairtwo's picture

    Hi,

    Thanks in Advance!! I really need help. I have just bought a minibus to convert, I really need help with the electrics in simple terms. Please can someone tell me exactly what I need??? I plan on running a fridge, tv, kettle and lighting. I would like a mains hook up and 12v. Please Help? I am trying to price it all up but not sure what I need! I have also thought about buying a cheap caravan and transferring all the electrics and interior?

    Thanks

    Rachel

    Apr 11, 2013
  • Ivecopaul's picture

    Hi Rachel,

    I am currently converting my Iveco 59.12 minibus I'm new to this, however i have searched the internet on other conversions.

    Your 12v set up is easy enough (just do it one wire at a time)look on web sites on how to convert a van, i bought a Haynes manual of of Amazon (build your own motor caravan) think its best to buy the 2nd edition as it covers in more detail on electrics. Its invaluable at around £20 well worth it.

    Your 240v hook up you will see you will need a garage type consumer unit with 2 or 3 trip switches and RCD built in to the one unit the RCD is VERY VERY important as it protects against any shorts as it will trip out. You will also need some sort of switch panel I'm going to use a Zig unit cf8 as it has a charger built in to it and some fuses. I think I'm right in saying you will also need to protect every electric item with in line fuses, make sure they are the right amperage for each item.

    Also maybe a good idea to fit a manual electrical shut off switch, just out side the sealed battery box.

    Just one more thing you say you might strip out a caravan for electrics just bare in mind i don't think anything will be marked up (labeled) as to where which wires go to what unless your willing to trace each wire back yourself and label with masking tape before removal.

    On new items such as consumer unit, switch panel etc will come with fitting instructions. These are useful websites for new and second hand parts,magnum motor homes, O'leary motor homes,UK classic car carpets, W4 limited, CAK tanks (for water tanks etc), and your local sheet wood suppliers for lining the van with plywood.

    For insulation i looked on Amazon i got a 1.4mtr x 50mtr x 4mm thick roll of foil insulation for about £130 (i have only lined the ceiling at the moment and its so much warmer already (seems to be very good stuff). Oh i also got a roll of 50mm x 45mtr roll of aluminum foil tape to join and seal the edges of the foil insulation.

    Lastly once you have your conversion PLEASE VERY IMPORTANT FOR SAFETY get it all checked by a qualified person, such as auto electrical person (for electrics) and a gas fitter for (gas).

    Good luck with all.

    Feb 03, 2014
  • Vadim's picture

    Hi Darren,

    Working on converting a 1998 Sprinter. Curious about 220v. From inverter to the plug, do I need to put either latching relay or DPDT? At the moment it has no fuse.

    thanks

    vadim

    Mar 22, 2013
  • Darren's picture

    Hi Vadim

    Are you connecting the inverter directly to the leisure battery?

    Regards

    Darren

    Mar 22, 2013
  • Vadim's picture

    Hi again Darren,

    Thank you so much for the reply.

    Yes, that is the idea, i was not sure there was another way. At least that is what I saw on other plans.
    The inverter is going to be connected to the battery and from the inverter it is going to go to the 230v outlet.
    What is the other option?
    I guess i can just put a regular 220v breaker?

    What do you think?

    Mar 22, 2013
  • Darren's picture

    Hi Vadim

    No, that is the best option, just checking you were doing that.
    You can put in a 220v breaker. The inverter should already contain safety switch and equipment. It will cut off if it cannot delivery the power, or if it senses a problem.
    Add a breaker for piece of mind, but you don't need too

    All the best

    Darren

    Mar 23, 2013
  • John's picture

    Good Day. You suggest a fuse when connecting the vehicle battery to a leisure battery, but I can't seem to find one that has a big enough connection for the 16mm cable that you recommend. If you use one of the inline fuses you can find online, they all have much thinner cable which surely negates the benefit of using 16mm cable between batteries?

    Thanks
    John

    Feb 17, 2013

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