Interior Wiring and Electrics - including info for leisure battery hook up

Discussion in 'Mech Tech' started by MadFrankie, Aug 12, 2011.

  1. Right, here goes...From a combination of google cached searches and some brain power, (on a Friday I might add), here are the useful bits I posted about interior wiring...

    What I want:
    - I want my leisure battery, (LB), charged as I drive along
    - I want all my internal electrics to run off the LB so I can still use them all when I'm parked up with out worry of draining my main battery, (MB)
    - I want to have the ability to plug in a 240v hook up if available and have it charge my LB, or at least run my internal electrics so my LB doesn't have to

    So, my diagram for this system is below. A few caveats before we start...

    - I am not a qualified electrician so am very open to comments or errors that may be on here, and don't blame me for any problems you have following this diagram, I'm happy to update it where needed.
    - The diagram is split into the different parts of the van so you should be able to follow where each bit is situated and how wires wind their way around
    - My van is LHD, so just swap it over for any RHD vehicles
    - I've taken various diagrams from various websites so it should be a pretty good diagram to follow
    - I'm using similar to a Ctek charger to power the 12V system when on hook up, but there are plenty of others about
    - I will have 2 x 240v sockets in the van. 1 will be powered from an inverter so will drain the LB quickly when not on hook up so will only be used sparingly or when I know I will be on the move soon after. The other will only work when on hook up and can be used to death as they won't drain the LB
    - Hook up plug will be located in the engine bay
    - I will probably locate the secondary fusebox, ctek, RCD etc, under the R&R bed and build a little unit to house them and keep them separate from prying fingers. The diagram shows the ctek unit and RCD in the interior units, I only did this to make it legible!
    - The colours and boxes of the wires / units aren't electrically correct, they are just colours...

    So here is the diagram:


    So, we have for my shopping list:
    1) Main Battery
    2) Self switching split relay - This one so far - £18
    3) Leisure Battery
    4) 240v Hook Up
    5) Fusebox - Like this one. Has 12 terminals and the common bars already in there, just wire and go. - £30
    6) RCD
    7) Charger - The ctek one, but might move up to the XS7000 as it seems the XS3600 is only really rated up to a 70Ah battery, it does go higher but at a stretch. - £44
    8) 12v to 240v Invertor
    9) Plug sockets
    10) Battery condition meter - This one looks quite tidy and you can easily put a switch on it so only switch it on when you want to see the volts in the battery, and it's pretty accurate. - £5
    11) Cig sockets
    12) Fridge
    13) Fuses
    14) 12v Wire - Something like this will be fine, just need to check the length of wire v current to make sure it's ok... - £5
    15) 240v Wire
    Fridge > Some split relays off you the chance to have a 12v wire from it to the fridge so that it charges the fridge when you're driving but cuts off when you stop to save the battery.

    Oh and you might like to get something like these and em=180664132073&ssPageName=STRK:MEWAX:IT#ht_500wt_1081">these if you are starting from scratch, they make the often tricky job of crimping, wire and cutting quite easy. Also, just got this as I just found my old voltmeter without a display!


    Question: What can I run on an invertor?

    Well, here goes!

    350W should be ok for most basic applications you'll use it for, so laptop or mobile charge etc but to be sure you do some maths:

    You need to remember the formula Watts = Volts x Amps
    NB, you can easily work this formula around to find either Watts, Volts or Amps:
    Volts = Watts / Amps --- Amps = Watts / Volts --- Watts = Volts x Amps

    It all depends on what you will have plugged in. Lets assume you want to plug a laptop into the invertor. Have a look at the transformer on the laptop. It'll have printed something like "Output 18v, 4A"
    You need to multiply the volts by the amps to give you a wattage figure - in this case 72. So you are drawing 72 watts, and then add 20% for inefficiency (its gets inefficient as it gets warm, for example), so call it 90 watts.
    Therefore, the 350W transformer is more than adequate! You just need to do this check with anything you think you might plug into it. To be honest you could get away with 200W for most items...


    Question: How long will my battery last?

    To work out how long a LB will run for you need to do some more maths I'm afraid:

    Your leisure battery is rated at 85Ah and is a 12 volt battery. At peak it has/had (when new) 85 x 12 watts (1000 give or take) total capacity. Take off 10-20% for age and overall usage (assuming it's fully charged). So 800w available. As you using an invertor to give you 240v to plug in your laptop transformer you can take off another 10%, just for the inefficiency of the invertor process.

    So you have available say 700 watts - and you are drawing 90w. Divide 700 by 90 - about 8, and that's the number of hours you should be able to run for.

    Now that is all assuming you are only running that invertor and nothing else, so no stereo / cig lighters / interior lights etc

    To get the total running time you just do the same maths for each thing wired to the LB and add it all together.
    Simples, I think!


    Question: What fuse do I need for each piece of equipment:?

    To find out how big a fuse you should have fitted, look for the Wattage information on the electrical equipment. For instance a television may require 300 Watts at 240 V.

    If you divide the rated wattage by the Voltage (300 divided by 240) = 1.25, therefore, this item would run happily on a 2 amp fuse, (in reality a 3 or 5 amp is fitted), this is OK but the lower the fuse fitted the safer the item will be as the fuse will blow quicker in the event of a fault.


    Approx watts for some Low Power Applications
    Digital camera - 3W - 19W
    Camcorder charger - 3W - 20W
    Mobile phone charger - 5W - 10W
    Portable work light - 8W - 60W
    Electric Razor - 10W - 25W
    Portable stereo system - 10W - 40W
    Light Bulb - 25W - 100W
    DVD Player - 35W - 100W
    Video game console - 39W - 100W
    Laptop computer - 60W - 90W
    X Box - 75W - 110W
    Baby Bottle Warmer - 80W -100W
    TV 55cm Screen - 85W - 160W
    Printer - 100W - 300W
    CD/Radio Player - 200W - 400W
    PC and Monitor - 200W - 400W
    Sander (orbital) - 250W - 400W
    Camp Kettle - 750W - 1200W
    Toaster - 800W - 1500W
    Coffee Maker - 1250W - 1500W
    Hairdryer - 1000W - 1000W
    Hammer Drill - 1000W - 1300W
    Vacuum Cleaner - 1500W -2000W
    Circular Saw - 1400W - 2000W
    This a guide only and is by no means a definitive list.
    Check that the inverter is correct for the application it is to do


    Power consumption of vehicle electrical leads (average values)

    Backup lamps 25W
    Battery ignition 20W
    Blower motor 80W
    Cigarette lighter 100W
    Fog lights 35W each
    Fog warning lamp 35W (red fog light on rear)
    Glow plugs 100W each
    Headlamps, low beam 55W each
    Headlamps, high beam 60W each
    Heated rear window 120W
    Horns and fanfare horns 25W...40W each
    Instrument-panel lamps 2W each
    Interior lamp 5W
    License-plate lamp 10W
    Parking lamp 3W...5W
    Radio 10W...15W
    Side-marker lamps 4W each
    Starting motor for truck 2.2kW...12kW
    Starting motor for car 0.8kW...3kW
    Stop lamps 18W each
    Tail lamps 5W each
    Turn-signal lamps 21W each
    Vehicle heater 20W...60W
    Windshield wiper 90W
    geordieandy likes this.
  2. Just a little tip, I have my charger wired to both batteries via a 3 position switch on-off-on so I can charge either the leisure battery or van battery at the flick of the switch.
  3. Looks good
    With the fuse rating make sure the cable is rated one size up to allow for volt drop.

    It is very important to make sure the body of the van is earthed to the incoming supply at the RCD.

    If fitting the supply plug in the engine bay take extra care not to damage the cable with the lid.
    A good place to fit the socket is under the van between the jacking point and the outrigger.
  4. I was planning on installing an on-off-on switch so I can charge either battery. My only concern is that if I accidentally knock the switch off - the Ctek may not like being on while the output is open circuit. So I was thinking about putting in a rotary switch but can't find one suitable.
  5. I fitted 240 volt electrics recently to Tilly.
    A consumer unit with RCD and earthed to Chassis is essential, easily wired from external plug to 2 x 240 sockets
    A Zig unit CF8 wired to the 240 volts system provides
    1 A ready made fuse and distribution system
    2 A split charge system that allows both batteries to be charged on the move or when on site
    3 All in house, DVD, interior 12 volt systems to be operated when plugged in on site without the danger of draining the liesure battery or worse the vehicle battery
    Because the Zig unit is a transformer it does generate heat so site where it ha s a good air flow around the unit and away from inflamables items.
    Just thought it may save you some time

    Cheers Steve
  6. Great post, I like that fuse box, its a right pain linking the things normally. :)
  7. Yeah, so far I can say it's been a god send, quick connect and you're ready to go. It also has a hidden benefit. If you want to make sure the appliance doesn't drain the battery if you aren't using the van for a time you can just pull the appropriate fuse! Also good for testing.
  10. At the time i was sourcing all the items you listed Frankie, the 12v shop didnt have it in stock. I sourced it at ECS though and thought i'd post the link for others. ECS is quite a useful little place for electrical bits and bobs. Also I wasnt happy with the split charge relay kit fuses using scotch lock connectors and i used some inline spade fuse holders instead from ECS and soldered them in. Ive also added 'isolators' to both batteries using quick release connectors.

    Next I plan to use these as on/off switches for lights, fridge, stereo, etc. Installed on the upstand fascia of the rock'n'roll bed. Along with battery condition guages

    I know i could buy a zig unit but this is more fun.

    Oh and as per youre question to vwwesty. The split charge relay you listed. My understanding is that its an intelligent relay. It knows when the main battery is fully charged and then directs it to the liesure battery. Thus if the battery charger is connected to the main battery and that battery is satisfied should it not then direct it to the liesure battery? Am i right or missing something?
  11. The split charge relay I bought was rated to turn on at 13.4v and off at 12.6v I get about 13.8v when charging. I guess if the main battery is very low it could pull that 13.8v down to below 13.4v and hence charge the main battery first, or at least get it partly charged up first. in practice though you are charging both batteries at the same time though

    If you're trying to size up an inverter or work out how long your LB will last dont believe whats printed on power bricks and phone/game chargers - typically that will be a maximum draw and often you'll find that the actual draw is lower.
  12. Can I ask what may seem like a stupid question but all this electrickery is complicated for a bear of little brain! ???

    If I follow Mad Frankie's wiring diagram will it be possible to charge up the leisure battery whilst connected to hook up; and as well as running the internal electrics off the leisure battery we could also run them off hook up. At the moment we can only have internal electrics such as lights and water pump running off the LB and have to plug in separate lights to use when on hook up.

    The bit I'm really not sure about is the split relay - does there have to be a physical switch to change from hook up to LB or is there a way of rigging it up so that it happens automatically. Apologies if this sounds really dense but to say I'm an absolute beginner where electrics are concerned is a complete understatement.
  13. The easiest way is have a battery charger plugged into the hook up and run all lights etc at 12v from the leisure battery.

    If you have any doubts about you abilities dont mess with mains hook up you are putting voltage that can kill into a metal box parked on damp grass.
  14. ^^^ WHS 110%

    The idea is everything internal runs off the leisure battery, regardless of where you are or what hook up you are or aren't on.

    The trick is then to have whatever electric charge you have recharging the main battery and then in turn the leisure battery.

    So, when you are driving along or have no 240v hook up you use the alternator to do it. This naturally charges the main battery in an engine so you connect the main to the leisure battery via a split relay.

    Now this next example isnt 100% accurate technically but will hopefully help you imagine the process, it's what I did to get my mind working in the world of electrics...

    Imagine all the wires in the engine are one way roads and that the electric moving around in there are little electric people in electric cars trying to get from place to place along the wire / road. Your aim is to find somewhere to park.

    So, the road we are interested in starts at the Alternator, goes along to the main battery, (MB), or car park 1, and then you build a new road, (add a wire), that goes from the MB to the Leisure battery, (LB), car park 2. In the middle of this road you put a traffic light, the split relay.

    Ok, the alternators job is to create the cars when the VW engine is on, so you start your journey there, you follow the road to the MB or car park 1. You try to park there, if there is space then you stay, if not you continue along the road until you hit the traffic light, (split relay).

    His job is a bit like a bouncer and he will make you wait there until he is happy that all the spaces in car park 1 are taken. When he is happy, he allows you through. You continue along the road until you reach car park 2, where you park up and end your journey.

    It's a bit of a crass example as it does ignore quite a few laws of electrics but there you go...

    As regards hook up, all this does is replace the alternator. So the 240v come in, gets converted down to 12v and then can eother go back down into your LB or to the back of your secondary fusebox to power your internal equipment.

    However, as Matty quite rightly says, if you struggle then get someone professional in as 240v, metal and wet don't mix at all well.
  15. thanks Matty and Mad Frankie for the advice- it is all becoming a little clearer.

    We did get a so called professional to some electrical work for us a few months ago but a 3 day job turned into a 3 week one and now we have less working than when we started - ho hum. Its our aim to get this sorted as our next job, I've got the cupboards out of the bus to renovate them as well so that should help with tracing the wiring back to source (that's the idea anyhows). Since I last posted though, this has been put on hold as my dear old dad (87year old) had a nasty fall last week and is in hospital with a broken hip - high as a kite on morphine and totally away with the fairies.

    Will post again with pics when we finish Ruby's interiors.
  16. I'm in the process of fitting out my camper with some internal electrics. I'm weighing up the pro's and cons of the PMS3, zig CF9 and Sargent EC155 etc against the buying the parts and wiring myself.

    Just found this.... looks like a wealth of information here and pretty much the exact situation I find myself and my exact requirements. i.e...

    What I want:
    - I want my leisure battery, (LB), charged as I drive along
    - I want all my internal electrics to run off the LB so I can still use them all when I'm parked up with out worry of draining my main battery, (MB)
    - I want to have the ability to plug in a 240v hook up if available and have it charge my LB, or at least run my internal electrics so my LB doesn't have to.

    I would like the 12V system to run:

    Waeco CR50 Fridge
    stereo headunit
    4 channel amplifier, not massive
    internal lights
    2 12v cig sockets

    Has anyone got a similar updated thread like this?

    As far as the split charge goes i've found this (link below) that looks the !@*#s, but is it worth £200??! is there a similar lower cost product?

    I imagine I will be going away for 3-4 days at a time, with a 2-3 hour drive at the start and end of the trip, but not much driving in between, I don't want the hassle of the battery's running flat. so keeping the batteries up to charge whilst on the go is important. Another [glow=red,2,300]FACT[/glow]or of having a good in built split charger is that when at home the van is parked on the street so the leisure battery will not be put on trickle charge as soon as it's home again. OK the battery can come out in the winter but don't fancy taking it out and putting it back in after every trip in the summer.

    Does anyone have any updated ideas stemming from this thread or similar?

    oh also, the van currently has a generator installed as opposed to alternator, is the generator going to be hopeless at running this equipment and need upgrading to alternator?



Share This Page