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12 VOLT 308 V8 INTO 24 VOLT MQ PATROL

Tech Talk for Nissan owners.

Moderators: toaddog, V8Patrol

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12 VOLT 308 V8 INTO 24 VOLT MQ PATROL

Post by yogi17 »

I'M PLANNING ON PUTTING A 308 INTO A 1982 DIESEL MQ PATROL.
i'VE GOT MYSELF AN ADAPTOR TO GO BETWEEN DONOR MOTOR AND MQ 4 SPEED GEARBOX, AND I EXPECT THAT ENGINE MOUNTS WONT CREATE TOO MANY HASSLES. MY CONCERN IS THE ELECTRICS.... BECAUSE THE 308 IS REQUIRING 12 VOLT FEED AND VEHICLE IS SET UP FOR 24 VOLT. WHAT IS THE BEST, OR MOST POPULAR WAY TO APPROACH THIS ???? YOGI17..
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    Post by Hoppy11 »

    Pm Screwy, I believe he put a a v8 in his 24 volt MQ

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    Post by V8Patrol »

    Delete one battery
    or
    re route the main power cables so its duel batteries and 12 volt
    at the moment you main cable goes
    negative, posative, negative, posative....... change it to
    negative to negative, & posative to posative, then run the earth from a negative terminal and the power wire from the posative terminal


    then.....

    change over the ...
    * heater fan motor
    * windscreen washer motor & relay
    all headlight and tail light globes

    * denotes a full replacement with a 12volt unit ..... trip to the wreckers !



    There's a brown wire in the loom on the drivers side near the battery... it gets pinned back into the loom ( doubled back)..... 2 min job at the auto elect's


    DONE

    :armsup:
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    Post by V8Patrol »

    V8Patrol wrote:...... change it to
    negative to negative, & posative to posative, then run the earth from a negative terminal and the power wire from the posative terminal
    I ran 2 earths .... one from each battery :idea:

    I ran the winch and the rest of the vehicles needs from the drivers side battery ( + terminal ) .......

    The passengers side battery ( + terminal) went directly to the engine's starter motor.

    :cool:
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    Post by money_killer »

    im sure u could get some sort of step down transformer to do the job.
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    Post by lolergram »

    I'm guessing the main issue would be charging the batteries from alty?

    You could fit a 2nd alty, maybe your old 24v one to the new motor.

    But I am not sure how to wire electrics if you have a split 12/24 volt car system.

    Hopefully someone else might have a bit more of a clue. ;)
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    Post by yogi17 »

    WHAT ABOUT KEEPING THE VEHICLE AND ALL THE STANDARD ELECTRICS IN 24 VOLT AND JUST RUNNING THE ENGINE STARTER MOTOR AND COIL IN 12 VOLT.? HAS ANYONE DONE THIS ? OR DOES IT CREATE PROBLEMS IN OTHER AREAS.?
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    Post by ausoops »

    centre tap the batteries for 12volt (ie where the lead that connects the first battery pos to the second bat negative is 12v with respect to chassis, tee off this cable for 12v supply) for the starter and coil then buy one of these http://www.redarc.com.au/ce.htm to re-equalise the voltage across the 24v bank.
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    Post by V8Patrol »

    "SERIES" wireing

    &

    "PARRALEL" wireing


    the two are differant ;)

    take ( for example) ten 12v batteries

    run the first batteries neg to earth and the pos to the starter motor
    for every other battery after that, the pos goes to the previous batteries pos and the neg goes to the neg.... repeat till all 10 are hooked up

    you'll have 12volts at the starter..... HUGE AMPS..... but only 12volts



    the other way of wireing is.....

    run the first batteries neg to earth and the pos on that battery goes to the neg on the next battery in line, that 2nd batteries pos then goes to the 3rd battery in the line NEG terminal ..... repeat till all 10 batteries are connected...

    you'll have 120VOLTS at the starter


    that one is how 24volt MQ's are wired.... :armsup:

    like this....
    first batteries neg to earth and the pos on that battery goes to the neg on the next battery in line, that 2nd batteries pos then goes to the starter motor.
    12volts plus another 12volts = 24 volts
    :cool:



    to change it to a 12volt system you must change it from -,+,-,+
    to
    -,-,+,+

    link the 2 pos's together..... link the 2 neg's together......

    one pos then feeds the system and the neg goes to earth






    why would you maintain the 24V system ??????
    why waste $$$ in 'transformers' ??????
    why fit duel alts ??????

    ITS SIMPLE

    CONVERT IT TO 12VOLT

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    Post by yogi17 »

    I SUPPOSE I HAVE A FEW OPTIONS NOW.
    THE MAIN THOUGHT WITH STAYING WITH 24 VOLT WAS PROBABLY THE CONVIENIENCE OF NOT HAVING TO CHANGE ALL THE HEATER MOTOR, WIPER/WASHER MOTORS, AND ALL BULBS. PLUS THE 24 VOLT EXTRAS I'VE ADDED OVER THE LAST 10 YEARS OF OWNERSHIP.
    BUT I NOW REALISE THAT THERE IS A LOT MORE UN-WIRING TO DO WITH REGARDS TO GLOW PLUG CIRCUTS AND THE LIKE.

    MAYBE I'LL KEEP AN EYE OUT FOR DEAD,RUSTY 12 VOLT PETROL PATROL AND DO A SWAP OVER OF THE WIRING LOOM AND ALL ACCESSORIES AS SUGGESTED BY SCREWY.
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    Post by neRok »

    my mate purchased a former 24v diesel with a 253 in it.

    the people that done the conversion retained the 24v system and alternator for the cars electrics and had hooked the starter, coil, fuel pump and thermo fan to 12v, which they took from the drivers side battery (PS- factory wiring takes its 12v from driver side battery as well for the radio and cig lighter. the 24v comes from the passenger side battery as explained by V8Patrol). All the 12v things were turned on via relays, which were hooked to a switch on the dash (like a kill switch, but they hadn't been hooked to the key at all). the relays were located on the passenger side, between the battery tray and the firewall, exposed in the open. they also ran one of those redarc equalisers to fix the batterys. all the diesel stuff behind the drivers side battery tray was still there as well.
    he had bulk trouble with this, batterys were always going flat, then the alternator died, was all a bit dodge but it was working. i wouldn't recommend doing it this way.

    then he started talking about putting in subs and amps and stuff, so i convinced him to fix it and make the whole car 12v, we done it in one arvo, easy as. first we decided to use the drivers side battery, because that way there would be less wiring running around the car. we also decided to ditch the second battery all together at this stage, as it was dead anyway and he didnt want to spend money getting a new battery or a dual battery system.
    so first point of attack was un-tapping all the wiring in the engine bay. then we pulled out all the relays and the redarc that had been added, which left us with the stock loom. we started at the alternator and ripped out all the wires which were 'useless'. this turned out to be most. FYI, the factory wiring all comes out of the drivers side of the firewall and runs around the front of the car to the passenger battery. so all the fuseable links that went to the passenger side battery stretched around the car already, so we cut all these back and hooked them up (with links) to the drivers side battery. All the wiring that went to the voltage regulator was removed (little module on passenger side near the headlight). then we removed to all the diesel components behind the battery cover on the drivers side. pretty much every wire came out here. the glow plug relay also hooks up to the battery, so this was removed. some of these wires go into the car, so we attached that part of the loom as well. next we removed the 12v accessory relay that is near the drivers side headlight. you can trace this back to the internal fuse block, we chopped it back and just hooked off the existing 24v accessory circuit. we then put in a new wire for the starter motor, but from memory i think the factory wire goes from the key to the diesel module and then another wire goes module to starter, so you could just link these. also, the power wire to key had some trickery going on, it got its power from somewhere wierd, so we ran a new thick wire to the battery and put a nice big fuse on the end.
    so that sorted out all the factory wiring. nothing needed doing to the headlights, dash, wipers etc.

    we removed the 24v alternator and replaced it with a single wire 12v one. the original conversion had already ran a big fat 100A+ wire from the driver side battery to the starter motor, so we just made up a short wire (fat as well) form the alternator to the starter motor. he replaced all the bulbs in the car and got some second hand sealed 12v headlights for $30. i think you can get them for about this price new as well (for 1, not 2 though). he still needs to replace the wiper motor, this works on 12v but it is a bit slow. he's not fussed atm, because it is summer. the car didnt have aircon and the original people didnt hook up the heater pipes (and he cbf as well) so we just ripped out the whole heater unit. gives heaps more leg room. only problem is he doesnt have a demister now, but i recommonded him this, which I run in my commodore because i ripped the heater unit out of it as well. http://www.calaisturbo.com.au/showthrea ... 563&page=3 - post 69 in particular

    then we knocked up the wiring for the relays for all the petrol stuff. we hid these behind the battery cover where the diesel stuff was, this way it was shielded etc. to do this, we ran a big fat wire from the battery down through the side hole and connected this to a fuse block. we used a separate fuse for each petrol thing, which fed a separate relay. we could have ran a single relay and fed that straight from the battery, but we decided not to. a standard relay is like 30A, which would be fine for running a fuel pump, coil and the small davies craig thermo fan he had at the time. he was however shopping for some falcon thermo fans. I have these in my commodore and hooked each fan on its own 20A fuse, because apparently they are rated in the mid teens each (so i was told at the time). so if running these, it may have been too much for the 30A fuse. if you were running the mechanical fan, I would probably just go the 1 relay, keep it simple.
    anyway, we ran a wire from the ignition of the key to signal the relays. this was just linked from one relay to the next. we did the same thing with the earth as well and just hooked this into a wire that was already near by in the stock loom.
    We had a small mishap at this stage, I was not aware but there is actually 2 ignition 'circuits' on the key barrel. They are both on when the key is at 'run', but when you turn the key to start, one of them turns off. and of course we hooked to this one. so when we were testing all our fresh circuits, we turned the key to run and were pretty pleased when everything was pumping and spinning as it should straight away. then we cranked it over and it spun but did not run. we were pretty devo, but worked it out quickly.


    so anyway, jist of my writing is just convert it to 12v properly. its heaps easier for everything, any accessories he hooks up now, he doesnt have to worry about where he is getting power from etc, or batterys dyeing when you in the bush.
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    Post by yogi17 »

    Thanks neRok, you make it all sound sooo easy.
    Mind you, I did go back and re-read some of it 3 times.

    I guess I agree..... WTF, do it properly, do it once.

    I will be keeping my 2nd battery though (only 6 months old) but as a
    duel battery setup. I have actually been running a 3rd battery up till now for my fridge and other 12v accessorys, but i'll have to wait and see if there is room for it with the v8 in. Thanks again.
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