Thoughts on 12v conversion on MEP-831A and MEP-803A possible or not?

[Leonardo]

I did search! But came up empty... So, I would like to explore the option of converting my generators to 12v. This would be better for me as every other thing I own is 12V and batteries are bloody expensive and do not seem to last as long as they use to anymore. Also the conversion to 12v would yield benefits for the life of the machine once done. I respect the hell out of the armed forces (Dad is Army vet who served in vietnam) and I understand why these things come in 24V but I have all 12V equipment and having a few generators that are 24V is a bit of a PITA for me. If I want to jump start one I need 2 sets of jumper cables and 2 separate batteries.... the 24V NATO cables are too expensive for me so that is out...


This is my plan for the 831A....

Playing around with my MEP-831A today and like most of you probably do, I use 2 motorcycle batteries in series. And I can't help but wonder if I could convert the starting system to 12v in order to not need 2 batteries. I am going to see if a $30 lawnmower battery will fit. it looks like it might fit with a bit of work to the battery box and hold down bracket. And even if a mower battery wont fit I believe I would still be better off using 1 motorcycle battery instead of 2....

What I realized is that this thing does not actually need a battery to run. It makes its own 24V so.... with that said, if i taped off the existing 24v battery cables and left them alone I could leave the 24V system intact and functioning how it normally does. Just not use it anymore. However the 24V system would still be there for the generator because I suspect it needs it. Next I would take the 24v starter off and replace it with a 12v starter and its own dedicated 12v battery cables going to a 12v battery. (inline fuses too) Then add a momentary push button contact switch to the generator gauge panel that engages the starter relay. Finally I would Wire in a 1-2 amp 12v battery trickle charger to the back side of the 10 amp 110v socket and connect it to the 12v mower battery so it would be charged whenever the generator is running.

I would like to know what you guys think of this plan and if I am missing any gotchas here that would get me into trouble. If this seems complex take a moment to read it over again and think about it for a few minutes. I am pretty confident this would work but I want to see what you guys think. In a nut-shell I would isolate the existing 24V system and leave it intact and alone. Then I would add a separate 12V starting system and trickle charge it with a battery tender jr wired to the back of the 110v 10a convenience receptacle. And boom a 12V conversion is born! At least I hope this is how it would go...... There seems to be a lot more knowledgable people here then me so tell me if you think this would work in your opinion or at least tell me why it would not work?


Now, onto the bigger MEP-803A...
This may be a little bit trickier. I don't think the same idea would work because the 803A is set up differently. I believe that I could change the starter to a 12v and add a single 12v battery and a button to push start it just like the 831a but I would probably need to disable and remove the alternator and replace it with a 12v alternator to charge the battery . Then add a dc-dc inverter which would convert the 12vdc into 24v dc to power the 24v system so that the generator still has 24v.

the process to start and run the generator would be quite simple, I would walk up and flip the switch to turn on the dc-dc inverter, then go around and turn the generator start switch to the run position, and finally press the momentary contact switch that I added which would engage the 12v starter. To turn the system off I would just to that in reverse.

I have been playing around with this idea in my mind for a while now and I can't see why it would not work. The only downside is that I would have to add a toggle switch to the dc-dc inverter so that I could turn it off when the generator is not running. The benefits would be the same as with the 831A...... 1 battery instead of 2. Half the cost of replacment. PLus the ability to jump start from my truck with a single pair of jumper cables.

What say you fine folks. Has my idea even got a chance of working?

 

[Mullaney]

I did search! But came up empty... So, I would like to explore the option of converting my generators to 12v. This would be better for me as every other thing I own is 12V and batteries are bloody expensive and do not seem to last as long as they use to anymore. Also the conversion to 12v would yield benefits for the life of the machine once done. I respect the hell out of the armed forces (Dad is Army vet who served in vietnam) and I understand why these things come in 24V but I have all 12V equipment and having a few generators that are 24V is a bit of a PITA for me. If I want to jump start one I need 2 sets of jumper cables and 2 separate batteries.... the 24V NATO cables are too expensive for me so that is out...


This is my plan for the 831A....

Playing around with my MEP-831A today and like most of you probably do, I use 2 motorcycle batteries in series. And I can't help but wonder if I could convert the starting system to 12v in order to not need 2 batteries. I am going to see if a $30 lawnmower battery will fit. it looks like it might fit with a bit of work to the battery box and hold down bracket. And even if a mower battery wont fit I believe I would still be better off using 1 motorcycle battery instead of 2....

What I realized is that this thing does not actually need a battery to run. It makes its own 24V so.... with that said, if i taped off the existing 24v battery cables and left them alone I could leave the 24V system intact and functioning how it normally does. Just not use it anymore. However the 24V system would still be there for the generator because I suspect it needs it. Next I would take the 24v starter off and replace it with a 12v starter and its own dedicated 12v battery cables going to a 12v battery. (inline fuses too) Then add a momentary push button contact switch to the generator gauge panel that engages the starter relay. Finally I would Wire in a 1-2 amp 12v battery trickle charger to the back side of the 10 amp 110v socket and connect it to the 12v mower battery so it would be charged whenever the generator is running.

I would like to know what you guys think of this plan and if I am missing any gotchas here that would get me into trouble. If this seems complex take a moment to read it over again and think about it for a few minutes. I am pretty confident this would work but I want to see what you guys think. In a nut-shell I would isolate the existing 24V system and leave it intact and alone. Then I would add a separate 12V starting system and trickle charge it with a battery tender jr wired to the back of the 110v 10a convenience receptacle. And boom a 12V conversion is born! At least I hope this is how it would go...... There seems to be a lot more knowledgable people here then me so tell me if you think this would work in your opinion or at least tell me why it would not work?


Now, onto the bigger MEP-803A...
This may be a little bit trickier. I don't think the same idea would work because the 803A is set up differently. I believe that I could change the starter to a 12v and add a single 12v battery and a button to push start it just like the 831a but I would probably need to disable and remove the alternator and replace it with a 12v alternator to charge the battery . Then add a dc-dc inverter which would convert the 12vdc into 24v dc to power the 24v system so that the generator still has 24v.

the process to start and run the generator would be quite simple, I would walk up and flip the switch to turn on the dc-dc inverter, then go around and turn the generator start switch to the run position, and finally press the momentary contact switch that I added which would engage the 12v starter. To turn the system off I would just to that in reverse.

I have been playing around with this idea in my mind for a while now and I can't see why it would not work. The only downside is that I would have to add a toggle switch to the dc-dc inverter so that I could turn it off when the generator is not running. The benefits would be the same as with the 831A...... 1 battery instead of 2. Half the cost of replacment. PLus the ability to jump start from my truck with a single pair of jumper cables.

What say you fine folks. Has my idea even got a chance of working?

.
Maybe some of the real Mobile Electric Power guys can chime in, but just converting from 24v to 12v is gonna cost you some serious money. The starter motors for example aren't cheap. I don't know the amp draw on the start motors either, but everything doubles when you go from 24v to 12v as well. A wagon made into a "Jumper Cart" of some sort with a pair of batteries would give you the ability to jump start either MEP. A house charger could keep the Jumper Cart ready to go...

 

[Evvy Fesler]

I ‘m wondering if a single battery can overcome the compression of a diesel engine?

 

[FarmingSmallKubota]

I think you just need to adjust your thinking a little. All you need to do is keep buying more Mil surplus equipment and magic no need to spend all the time and money on a conversion. You have 2 now so your well on your way. slave cable and more equipment done.

 

[DieselAddict]

Put on a 12v starter with a button to engage it and leave the rest of it as it is. Should work fine.

Use a 12v charger wired into the 120vac to recharge the starting battery.

 

[Evvy Fesler]

@DieselAddict, does the MEP-803 have an exciter circuit?

 

[kloppk]

Like the 831 the 802 can generate it's own 24 volts with the alternator. An 802 will run without batteries. They are only needed to start it or 24 volts in thru the slave port to get it started.
The minor hitch is the alternators exciter will need 24 volts momentarily to get it generating 24 volts if you use a 12V starter.

 

[DieselAddict]

@DieselAddict, does the MEP-803 have an exciter circuit?

it does. My comment is more applicable to the 831 since it has a permanent magnet alternator and doesn’t need an external jump to excite it.

You could use a 12v to 24v boost converter to excite the systems on a 802/803 once you start the engine With a 12v starter.

 

[kloppk]

Another gotcha on the 803. You'll need 24 volts for the fuel solenoid to retract to allow the engine to start.

 

[kloppk]

If you need the glow plugs for cold starting you'd need to modify their wiring to get 12v to each heater element.

 

[DieselAddict]

Another gotcha on the 803. You'll need 24 volts for the fuel solenoid to retract to allow the engine to start.

If I were going to try this I’d put a 12v starter on the engine. I’d use the boost converter to power up the 24v systems on the generator. I’d energize the 12v starter solenoid from a Relay on the 24v starting circuit.

The starter cutout could be used to disconnect the boost converter when the engine started.

 

[DieselAddict]

But for my $$$ it’s a lot easier to buy a couple of lawnmower batteries for like $75 and put them in series. Done.

 

[Ray70]

Forget trying to convert the 803. Like others have said, it will be much cheaper to simply buy batteries than to convert it.
A while ago I posted an article about my son putting a DN2M into a John Deere garden tractor, I also wanted to convert it to 12V but found it would be impractical and virtually impossible. I looked for a 12V starter and found a couple that appeared as if they would work, but then came across a guy who seemed to know a bit about the civilian versions of the DN2M with 12V systems and he said I would need to change the flywheel too because the 12V starter wouldn't work with the MEP's flywheel. So we left the engine 24V and used a bunch of relays to keep the engine 24V but the tractor 12V.
You can either get a couple cheap batteries or get something decent that will at least have a 3 year warranty. Believe me ( and the others ) it will be cheaper and easier in the long run!

On the 831 I've found that a pair of 12V 21AH SLA batteries from a jump pack / emergency light application ( available for about $40 each ) fit well and work perfectly. Or just forget the batteries and pull start it or slave cable off your 803.

 

[Mullaney]

Forget trying to convert the 803. Like others have said, it will be much cheaper to simply buy batteries than to convert it.
A while ago I posted an article about my son putting a DN2M into a John Deere garden tractor, I also wanted to convert it to 12V but found it would be impractical and virtually impossible. I looked for a 12V starter and found a couple that appeared as if they would work, but then came across a guy who seemed to know a bit about the civilian versions of the DN2M with 12V systems and he said I would need to change the flywheel too because the 12V starter wouldn't work with the MEP's flywheel. So we left the engine 24V and used a bunch of relays to keep the engine 24V but the tractor 12V.
You can either get a couple cheap batteries or get something decent that will at least have a 3 year warranty. Believe me ( and the others ) it will be cheaper and easier in the long run!

On the 831 I've found that a pair of 12V 21AH SLA batteries from a jump pack / emergency light application ( available for about $40 each ) fit well and work perfectly. Or just forget the batteries and pull start it or slave cable off your 803.

.
Thanks @Ray70 !
I knew there had to be a voice of reason around here that had considered it before!

 

[Guyfang]

Why "Fix" something that aint broke. In the end, you will have something that will cost 4X the cost of two cheap batteries, AND you will be sorry for the rest of your life.