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120 Series Leisure Battery Power Supply

Gary Stockton Feb 25, 2010

  1. Gary Stockton

    Gary Stockton Super Moderator Supporter I am in zimbabwe

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    The Euro 120 Series Land Cruiser comes standard with 2 batteries under the bonnet (hood). In order to run a fridge or other 12volt appliances when overlanding, a 3rd deep-cycle battery is needed to ensure you don't drain the starting batteries. So I decided to install one in the load bay on a semi-permanent basis, and thus had to pull cables to the rear to supply charging surrent tot he battery.

    Completed the installation of the cabling and solenoid and auto-voltage sensor today. Once I decided on the cable routing it worked out quite well.

    Primary battery and solenoid (not really visible - behind the diesel fuel filter) on side wall:

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    Grommet on right to shove wires through - they come out behind the glove-box (note - not the cubby-hole anymore ... :lol: )

    002.jpg

    This is where it all comes through:

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    Mr T kindly left some room in the channels under the door sills for me:

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    Be careful not to break these stupid flimsy clips - a bit of sideways movement is all it takes :cry:

    006.jpg

    Then ran the cables thought the same channels in the back door, then up under the carpet under the rear seat to exit through the hole in the carpet next to the tie down ring. Batter connected, and all works as intended!

    Happy days!

    After a break, decided to complete the job ...

    Clearly this has been a weekend for finishing stuff off. Finally got round to completing the wiring through to the rear - it's been a semi-permanent Heath-Robinson affair to now, so this has finished it off quite neatly, and permanently.

    I pulled the left rear inner panel out so I could get a good lookbehind it - I've been procrastinating over where to bring out the cables, and how to sort it all out. I bought a couple of 165 amp Anderson plugs to bridge from the vehicle to the batery, and have been putting off drilling holes. :lol: Dunno why, considering I drilled a sodding big hole in the wing for the snorkel :shock:

    So here we are:

    PowerSupply001.jpg

    PowerSupply002.jpg

    PowerSupply003.jpg

    PowerSupply004.jpg

    Then I finally completed the cable from the battery to the solenoid, via the mega-fuse, wrapped it in a split conduit and shrink-wrapped the ends - looks almost like a bought one!

    PowerSupply009.jpg

    PowerSupply007.jpg

    PowerSupply008.jpg

    PowerSupply006.jpg

    Found a nice high spot on the firewall to mount the solenoid:

    PowerSupply005.jpg

    So that's that done - power flows when the batteries are charging and alternator is kicking out 13 volts or so (or something like that - I dunno - but it works, and isolates when the engine is off ...). Hardest part was getting the damn grommets in place ... :p

    Still to come - the Packing System, with a bespoke battery box and distribution points ...

    Cheers
     
  2. AndyCook

    AndyCook Well-Known Member I am in scotland

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    Hi Gary

    what solenoid did you use for this - brand if poss, but I am also interested in ratings.
    I am after a cheaper setup than the IBS system which is now around £200....

    cheers
    Andy
     
  3. AndyCook

    AndyCook Well-Known Member I am in scotland

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  4. Gary Stockton

    Gary Stockton Super Moderator Supporter I am in zimbabwe

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    That looks like the one I got - I just specified the length of 25mm square cable I wanted, and bought a hydraulic crimper on ebay for £25 and all was happiness!
     
  5. Steve Wright

    Steve Wright Well-Known Member I am in great_britain

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    Hi Gary

    As you have put the cable in, I hope you are not going to use it for starting, or running a winch, over that length
    you need at least 50 mm, as 25 mm it only good for about 175 Amps 50mm is good for about 350 amps, but you also
    need to take into account the volt drop over a long run.

    Steve
     
  6. Gary Stockton

    Gary Stockton Super Moderator Supporter I am in zimbabwe

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    Cheers Steve - yep, did the sums - this is just to put a power point in the load bay to charge a 3rd leisure (deep cycle) battery. Been adequate so far :roll:

    Cheers
     
  7. Crispin

    Crispin Administrator Staff Member Guru I am in great_britain

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    Is there any reason one cannot buy some welder's cable? Cheap, flexible and, well, cheap.
    It's not low grade copper or anything like that?
     
  8. Graham

    Graham Well-Known Member I am in uk

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    Well I was pricing the welders cable,
    firstly because it is stranded, and nice and flexible.
    The down side is it is normally only rated to 110 volts, which don't really affect us on 12 volts.

    I was given a price of 2.40 for 25mm and 2.50 for 35mm.

    I just want it to supply the 2kW inverter I bought from Paul.
    I think 25mm cable is rated about 100 amps, or there abouts ?

    More than sufficient for the 2kW inverter running some small appliances.

    I am opting for a battery isolator, mounted on the battery, as a way of manual isolation.

    Graham
     
  9. Gary Stockton

    Gary Stockton Super Moderator Supporter I am in zimbabwe

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    A quote from my favourite lesson on electrickery, and forgive me if I'm preaching tot he converted here ... ;)

    Today's lesson - Power

    Power is the product of Voltage and Current (P = V x I) and is rated in Watts. Power is not usually measured, it is calculated.

    It is important to know the power of a device as we need to know how much current it will consume. Not many devices are labelled with the current consumption, but most do list the power rating.

    As an example, SWAMBO wants to take her hairdryer in the back of your Cruiser. The hairdryer is rated at 1500W @220v.

    From the formula, P=VxI; I=P/V
    1500W/220v = 6.8A

    OK, so the camp site you're at doesn't have 220v. You knew this before you left which is why you installed a 1500W inverter (we're living in a perfect world for the moment). How much current will flow on the primary, 12v, side of the inverter?

    I=P/V
    I=1500W/12v
    I=125A


    So you will need cable capable of sustaining a draw of:

    I=P/V
    I=2000W/12v
    I=166.67A

    Cheers
     
  10. Graham

    Graham Well-Known Member I am in uk

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    Nice Gary,

    Thanks.
    I only plan on using the inverter to run a couple of small 220 volt consumers.
    Fridge, freezer, DVD - TV, lap top,
    I would be very surprised if my total load exceeded 500w.
    It does mean though, that the 2kW inverter will not run hot, and will indeed enjoy a happy life.

    Interesting
    http://www.autoelectrics.net/battery_cable.html


    The 25mm welding cable has actual capacity for 120 amps,
    The 35mm welding cable has actual capacity for 240 amps,

    Graham
     
  11. Gary Stockton

    Gary Stockton Super Moderator Supporter I am in zimbabwe

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    I think the point I'm trying to make (and I may be entirely wrong here - it's happened before :doh: :lol: :lol: ) is that you've got to run the inverter properly. So - does the inverter consume 2kw irrespective of what is hanging off it, or does it only draw what is required to run whatever is hanging off it??

    If it always runs at full tilt, you'll need to sustain the load. If not, you'll need to total up the cumulative draw + some extra for safety / resistance / start-up current draw for non soft-start equipment, etc.

    I'm sure someone way smarter than me with electrickery will be along shortly to confuse me more :whistle:
     
  12. Graham

    Graham Well-Known Member I am in uk

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    Hi Gary,

    If I am only drawing 200w from it on the 230v side, then the input amps is proportional.
    Plus to the extent they are rated 95% efficient.

    So example, 200watt load on a 2kW inverter is 10% of full load.

    So very briefly, 200/12 = 16, 6 amps input, and just add the inefficiency factor of 5%

    Give or take 17 - 18 amps on the 12 volt primary side as an input.

    Graham
     
  13. Crispin

    Crispin Administrator Staff Member Guru I am in great_britain

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    Just go with the proper rated cable.

    One day you'll forget you only wired up your shiny 2KW invertor for 500W and you'll plug your hair dryer in. You'll either (hopefully!) pop your 50A fuse or stand back and watch the 100A cable getting hotter than the hairdryer.
    If you really want to do it, get a 2A CB and put that on the 230v side. The cost and hassle of that outweighs the cost of putting the correct cable in first.

    Any chance of setting your cruiser on fire is a silly chance. Popping a 50A fuse in the middle of nowhere without a spare, annoying.

    I'll sit down now. :mrgreen:
     
  14. Crispin

    Crispin Administrator Staff Member Guru I am in great_britain

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    Wanted to ask, has anyone actually cranked their's upto the 2KW and seen it run? I know they run quiet and cold but would be interested to hear. (pun intended) :mrgreen:
     
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