24v start on 12v system

[trailerman]

Hi PEG ! yes your right about the Cummins having a 12v version ! But you have to change ring gear too a hard part to find as its off Leyland Roadrunner which was taken over by DAF , Ive been down that road and burnt the bridge, that route is out for me.
The build is for a long haul camper ! built to go anywhere with readily available parts and the parts I cant get will be with me on my travels thanks for input

 

[PEG]

See my edit^^ ,also,i cannot remember ring gears being changed on any conversions i have been involved in,not saying it has not occurred...starter bodies and mounts are the same,so i would change drive gear at end of inertia unit,on starter...this, i have done.

I know it is not identical,but i put a NTC350 in a 50 year old Menck crane,that had 12 volt electrics (minimal) and 24 volt start...a mere case of stunt jump-leading first thing in the morning,then happy days digging...just picture "Endo" the torturer with jump leads,in "Lethal Weapon"..and you have it! :icon12:

 

[davesparks]

The build is for a long haul camper ! built to go anywhere with readily available parts and the parts I cant get will be with me on my travels thanks for input

Just buy a landrover!

 

[trailerman]

No LR for me ! I cant get comfy in those,driving position kills me ! anyway Im well past that stage ,if I knew how to upload pics on here would show you where I am then you would know theres no turning back ! not that I would ,Ive been running Transits since 1979

 

[Lucien Nunes]

If there is room, a separate 24V battery (2x 12V in series) just for cranking would be safest. This could be permanently connected as 24V and charged from an isolated 12V-input 24V charger. There would then be no risk of damage to the 12V system in the event of a fault on the 24V, nor any high-current series-parallel switching. The 24V starter solenoid would be energised by a heavy relay with a 12V coil connected in place of the old 12V solenoid. The only drawback is the need to find space for a 24V battery.

 

[trailerman]

Now we getting somewhere in the region I want to be , I do want 12v system to stay standard and separate start ! unless theres an easier way for 24v start , there has to be a LR nut on here that knows about there 24v start up system ,big thank you to all for keeping this going ,please keep going

 

[davesparks]

LR nut? I think I probably fit that description, I've got one doing great work as a driveway ornament at the moment
But it's ok cos I've got another that's currently working

 

[PEG]

I cut my teeth on a series IIa ex-army yoke,WMA605J,which before i was 17,i had fitted a 2.2 BMC,vacuum governed(yawn),a P6 HC V-8 (brakes pointless),and finally,a Mercedes OHC 306 Diesel (was told would NEVER go in)...got converted to Jap,and never looked back...have a rake of pals with newer Rangerovers,all giving the emperors new clothes speech...There is one thing you should NOT be doing,after spending £90,000+....

.....and that's walking :icon12:

 

[trailerman]

Davesparks and Peg ! we seem to be playing ping pong very well ! I can see yous both have wealthy knowledge as well as others !
I know Im in the right place now to solve this ! for sure ! thank you for your time in helping / troubleshooting ! how do I upload pics and will show yous what I have and where I am might kickstart more ideas

 

[trailerman]

Anymore ideas ?

 

[trailerman]

Would this work !
connect one 12v battery as normal to your vehicle then take a lead from the positive terminal to another 12v battery via a 24v solenoid and join it to the negative terminal then take a lead from the positive terminal via a 24v solenoid to the terminal to the starter motor,the 12v charging system will work as normal providing you connect the charging wire from the alternator to the second battery 12v positive terminal

 

[Lucien Nunes]

Er, no. You will end up with 24V across your 12V alternator when starting and an airgap when not. For series-parallel working you need three solenoids in addition to the starter's own, and they ought to be interlocked because closing the wrong combination of them will melt wiring / destroy batteries.

 

[gavin.sibley]

Of course space is going to be tight, you're trying to shoehorn a 6BT into a transit!
In theory you can use two batteries and some high current solenoids to connect them in series for cranking then return them in parallel for running/charging.

Easy fix! Put it in the back, loads of room in there!!

 

[trailerman]

Yeah its Mid engined anyway,got the room ! somebody sent that theory to me and I didnt trust it,so posted here to get feedback !! thank you lads for your input ! any more ideas

 

[Lucien Nunes]

I think you've had all the sensible options already:
a) separate 24V batt and second alt
b) separate 24V batt and step-up charger
c) permanent series, charge second batt with isolated 12V-12V charger
d) series/parallel switching, charge second batt directly from existing alt