404 12V conversion: my idea.... your comments? suggestions?

TigerMog

Hello all!

I have been off on operations for the last 6 months with nothing better to do than think up new things to do to my Mog. Now that I am back, first on my list of ideas is an electrical system upgrade. I know there are arguments both ways for 24V vs 12V. Suffice to say that I have decided I want to convert to 12V. I can pick up a new alternator, lamp bulbs etc at the local parts store, run GPS, a stereo etc. The lone stumbling block in my plan is the starter. I have yet to find a decent 12V starter. From what I have found so far they are all cheap shyte. This leads to my plan for how to manage a 12V system and a 24V starter.

A 12V 140amp GM alternator is almost a bolt in replacement. It fits perfectly. A new modern fuse panel from painless wiring sorts out the rest of the electricals with no fuss.

My plan (and the bit I want advice and comments on) is to run THREE batteries instead of two. Battery number 1 will be wired into the full electrical system and will be the source of the 12V system. Battery 1 will NOT be in any way connected to the starter.

Batteries 2 and 3 will be wired in series to make the 24V power source for the starter. All fairly straightforward so far until I tried to decide how to charge them from a 12V system. Here is what I came up with: I will install a master kill switch in line between batteries 2 and 3. The battery cable going from the positive post of battery 2 to the negative post of battery 3 is routed through a keyed kill switch to effectively isolate them from each other when necessary.

From the main relay off of the alternator I run a 10 gauge wire to a toggle switch and from the switch the wires will run to batteries 2 and 3.

What this allows me to do (in my head at least) is to isolate battery 1 for normal use when running.

During startup I turn OFF the toggle switch that provides power to batteries 2 and 3. This separates Batteries 2 and 3 from all contact with the 12V system. I turn the main kill switch between batteries 2 and 3 to ON. Now the batteries are connected in serial and provide 24V to the starter.

Once the vehicle is started, I turn the main kill switch to OFF separating batteries 2 and 3 making them 12V each respectively. Turn ON the toggle switch to provide a charge from the alternator.

Will this all work? So far I can find only two things that MIGHT be an issue for me.

1) charging three batteries may end up being a significant drain, but I believe the 140 amp altrernator can cope.

2) will charging battery 3 even be possible? With the main kill switch in the OFF position isolating the batteries a ground for battery 3 is the issue. Battery 2 is grounded, but the ground for Battery 3 is routed through the kill switch to the positive terminal of battery 2. Once I put the kill switch in the OFF position, battery 3 effectively has no ground. Will it still take a charge?

Any thoughts and comments are appreciated!

minimog · Off-Road Guru Joined: 25 Nov 2004 Odometer: 1700

what about seeing if the 411 or 421 starter will fit they run very similar gearboxs or even the merc car veriant m180 engine all are 12v
other than that what about using a voltage droper for everything and still keep the 24v starter(i think thats what moggs did with his to run the 12v ignition)

dxmedia · Mud Obsessed Joined: 10 Dec 2008 Odometer: 2185

Or just pull 12v from tapping one battery before the link to 24V?

OK the current drain will be slightly mismatched, but it will not have a huge effect on the batteries.

TigerMog · Posted: Fri May 15, 2009 3:55 am Post subject:

If I could find a reliable 12V starter that would bolt in would be the very best scenario. I just haven't been able to identify one yet.

I am currently pulling 12V from one of my 2 batteries now. So far it works, but there are problems with it, and it doesn't solve my desire to be able to purchase "normal" parts at the local store rather than have to mail order everything specifically for a 24V system. I really want a true 12V system at the end of the day.

So if you know anyone who is interested in a 24V warn winch, I will have one available soon!

dxmedia · Mud Obsessed Joined: 10 Dec 2008 Odometer: 2185

jeepmadmike · Posted: Sat May 16, 2009 6:34 am Post subject:

24v electrical systems are more reliable than 12v

A 24v starter will be more effiecent<cant spell

12v is easily obtained as stated above

I have gone the other way before 12v system to 24v it makes no sense to downrate.

24v bulbs etc are dead easy to get every town will have a factor or auto elec or farm shop which sells them- just not halfords

TigerMog · Posted: Sat May 30, 2009 6:36 am Post subject:

For right or wrong, I am going to convert to 12V. I found a company to rewind the starter converting the original starter to 12V and sorting out the issues. Will keep posted on how it all plays out.

TigerMog · Posted: Wed Jun 17, 2009 7:30 am Post subject:

UPDATE

The upgrade is going well, but the project has expanded as they all seem to do. When I pulled off the fan pulley I found the water pump had a small leak.....so.....we now have an all new and modified cooling system. New water pump, new electric fan (12V), new silicon hoses, and aluminium pipes. But the coolest thing about the whole process was that I took the overflow tank out of the dash and binned it. The local radiator shop was able to knock a hole in the top of the rad and braze on a new flange with radiator cap and overflow outlet. New stainless over flow is mounted on the inner fender. No more boiling hot summer days with a hot water tank in the cab!

The fuse panel / wiring loom from Painless Wiring is brilliant. It is color coded and every wire is labeled every 6" which makes sorting it out a breeze. The wires are also plenty long to do everything from headlamps to tail. I mounted the fuse panel in a small military ammo cam high between the seats on the back of the cab. Not totally waterproof because of the hole to route the wires through, but still pretty secure place for the heart of the electric system.

With the boiler out of the dash, I now have somewhere to mount a stereo that hooks up to the 12V system with no issues.

I finally found a gent that had converted to 12V and found a 12V starter from BMW that bolts in with just a ring gear change. Saves me from having the original rewound.

A small bit of grinding had the new GM alternator mounted up using the factory Mercedes mounts.

This weekend will hopefully see a new set of Stewart Warner gauges filling the dash if all goes well.

Next up.......hydraulic power steering to handle 42" tyres! muahahahahah

dxmedia · Mud Obsessed Joined: 10 Dec 2008 Odometer: 2185

Brilliant

Sounds like it's really coming along.

Leccy fans are pretty high up my own list, I was planning on a set of ford v6 fans and pulling 12v from one battery.

Do you have a link to the painless wiring site? I've found painless performance but they don't have anything mog related. Thanks,

TigerMog · Posted: Wed Jun 17, 2009 1:37 pm Post subject:

I bought everything from summit racing in the states.

www.summitracing.com

They have the full line of painless goodies from switches to fuse panels etc. They dont have anything Mog specific, but they have gobs of universal fit "hotrod" set ups. I have used their fuse panels, switches etc before on 24v applications without issue.

One word of advice on the electric fan. Check the thickness of the fan not just the diameter! The space between the rad and pulleys is thinner than you might think!

dxmedia · Mud Obsessed Joined: 10 Dec 2008 Odometer: 2185

normalbloke · Articulating Joined: 29 Aug 2007 Odometer: 633

Hey Dan, how's things?Coming out to play anytime soon??

TigerMog · Posted: Thu Jun 18, 2009 5:09 am Post subject:

Absolutely! As soon as I get the last of the electrics converted I will be dying to go out and play some more!

normalbloke · Articulating Joined: 29 Aug 2007 Odometer: 633

Good man!
Glad your last trip was ok!
We have a date of the 28th pencilled in for Hogmoor Enclosure,same town as the last trip(Bordon) but a different site.
I went there on Sunday,it was a great site, but I got distracted with a lot of recoveries and had to tow my friend's Jeep home after he smashed his transmission case! doh!
catch up soon!

mike97 · Guest

On the subject of going out to play, have either of you guys been to the 'Muddy bottom' site near Lyndhurst? Been up there with a friend in a land rover a few months ago and its an awsome site, now i've got the mog on the road, really looking forward to taking that out for a play, quite local for me too! Very Happy

TigerMog · Posted: Fri Jun 19, 2009 5:32 am Post subject:

I dont know if I will be fully operational by the 28th. That will be cutting it close. I guess it all depends on how the mail order parts do on getting here in time. I would love to go back again though!

As far as playing near Lyndhurst? I am just around the corner in Marchwood! I would love to find some more local playgrounds.

normalbloke · Articulating Joined: 29 Aug 2007 Odometer: 633

TigerMog · Posted: Thu Jul 30, 2009 9:48 am Post subject:

Minmog,

I actually JUST finished the whole conversion this week. The starter ended up being the one sticking point that was holding me up for weeks on end. I will get some photos pulled together and post a full update with all of the details on what I used, what worked, and what didnt.

Specifically for the starter, I wasnt thrilled with rewinding the factory starter to convert it to 12V. It is possible, but I am just not thrilled with that option honestly. After getting some terrible service from a few other shops (which held the process up for weeks at a time) I came on Nippon Dist. in Sutton Coldfield. Fellow there name Barry more or less built me a custom starter. I sent in the factory unit, he found a starter with a matching nose cone, then mated up a motor that matched the Kw output, found an appropriate ring gear etc. At the end of the day I do not have a part number to give you, but can say it engages more smoothly and spins faster than the stock unit ever did.

Of course it started as a simple conversion and then spiraled out of control and ate up far more time than expected. These projects always do. But I am very pleased with the outcome now.

mike97 · Guest

Hi Dan,

I too am going the 12volt route soon, nothing against 24, but I have a diesel conversion in the pipeline which has 12v starter, alternator and glow plugs, so it makes sence to change to 12. Rolling Eyes

Just one question, what did you do about the wiper motors??

cheers Mike

TigerMog · Posted: Fri Jul 31, 2009 9:16 am Post subject:

For the small items like the wiper motors and heater blower motor, the drop in voltage just isnt that big of a deal. Obviously the starter motor needs the torque, but the wiper motors just run a bit slower, and fan blows a bit weaker and I am still happy with them as is.

crblanleil

Hi there,

I just started to go through the 12V change over and ran into the same problem - the starter... can you post some details or a number or email to contact the guys who did it for you??

Thanks
Claude

johnhughes · Gate Opener Joined: 01 Dec 2009 Odometer: 40

A common landrover conversion used to be the Nissan 3.3 diesel in its various forms. it was 24v starter but used a 12v altenator, gauges etc. Nissan did it by having 2 12 batteries wired in parallel to give effectively a big battery for lights etc and big special Nissan relay controlled by the starter key that connected them in series purely for the starter for the duration of the starter run.
problem solved

j

TigerMog · Posted: Fri Dec 11, 2009 8:36 pm Post subject:

Two options for a decent 12V starter really. Trust me I went through LOTS of attempts at a decent one. Finding someone in the UK willing to rewind one from scratch was near impossible.

I ended up going with Nippon Distr. here in Sutton Coldfield, West Midlands. They basically took my old starter, ripped it apart and found bits that matched...i.e. nose cone that fit and mated it up to an appropriate motor and ring gear to make me a custom starter.

http://www.exchange-starters-and-alternators.co.uk/index.htm

0121 311 0313

The only problem is that the ******** kept my original 24V starter Sad

Have called and e-mailed a few times and finally gave up on getting whatever was left of it back.
Not sure what I would have done with the scraps of it, but it was mine and I expected it back.

The other option I found, that is actually probably better, but has to be ordered from the US is from the Mog Shop.

http://www.themogshop.com/index.html

Their starter will run you about 225 GBP at todays exchange rates. The reason I say it is better is that they offer a high torque gear reduction starter.

If you go with Nippon tell him I am still waiting for my bits back!

dave404 · Posted: Sat Dec 12, 2009 9:49 am Post subject:

For 12v rewinds try these guys in Yeovil, somerset

http://www.carwood.co.uk/yeovil-location.html

They have rewound some very unusual starters and alternators for me in the past. They use to be called Lucas rewinds before the demise of Lucas UK.