MEP 831 FAQ for owners or potential buyers

[Statewide]

I have a friend who has a 831, he has power at the convenient receptacles but none on the main power lugs ( in any configuration), we did find one burnt relay behind the control panel, replaced it no glory... anybody run into this or have any ideas??

 

[DieselAddict]

You'll want to grab the Technical Manual from the manual section of the forum and do a bit of quick reading to get up to speed on how these things work.

If you have power at the receptacle but not the lugs (assuming you flipped the switch) you need to troubleshoot the circuit that energizes the power contactor and troubleshoot the contactor itself.

There are several troubleshooting guides that will help immensely.

https://www.steelsoldiers.com/showthread.php?155865-Manuals-for-the-MEP-831A

 

[Guyfang]

I have a friend who has a 831, he has power at the convenient receptacles but none on the main power lugs ( in any configuration), we did find one burnt relay behind the control panel, replaced it no glory... anybody run into this or have any ideas??

Have you downloaded the TM?
Have you ever seen this gen set work right? Is it new to you?
What relay did you find burnt.
Are you sure that you replaced it with the right relay? K12, K14 and K15 are not all the same relay.
Do you know how to use a multimeter?
Can you read a schematic?

 

[Guyfang]

Have you downloaded the TM?
Have you ever seen this gen set work right? Is it new to you?
What relay did you find burnt.
Are you sure that you replaced it with the right relay? K12, K14 and K15 are not all the same relay.
Do you know how to use a multimeter?
Can you read a schematic?

You really need to start your own thread on this problem.

 

[Mogman]

What a piece of JUNK!! even after you get all the controller issues fixed all you end up with is a generator you cannot run inside (as with all generators) and despite the fact it has a solar panel to charge the batteries you cannot leave it outside because the slightest amount of moisture and the thing will shut down on "overload/short circuit" (I have read MANY accounts of this, not just me) what a POS......

 

[CallMeColt]

What a piece of JUNK!! even after you get all the controller issues fixed all you end up with is a generator you cannot run inside (as with all generators) and despite the fact it has a solar panel to charge the batteries you cannot leave it outside because the slightest amount of moisture and the thing will shut down on "overload/short circuit" (I have read MANY accounts of this, not just me) what a POS......

I had let mine run in the rain overnight & didn't have that issue. Also had a return fuel line blow & it ran all night coated in diesel another time. Sounds like there is an actual short that is showing itself when it gets wet. Maybe a common area that shorts?

 

[Mogman]

I had let mine run in the rain overnight & didn't have that issue. Also had a return fuel line blow & it ran all night coated in diesel another time. Sounds like there is an actual short that is showing itself when it gets wet. Maybe a common area that shorts?

After doing some searches it appears the inverter does not like moisture, I now have three of these and if it rains one will have issues, if it rains hard enough two will have issues, I assume they stay warm enough while running moisture is not a problem, all of them will work if run for a while and warmed up then restarted, if I ever get the time I will tear the worst one down and coat the insides of the inverter with dope and see if that helps.

 

[CallMeColt]

After doing some searches it appears the inverter does not like moisture, I now have three of these and if it rains one will have issues, if it rains hard enough two will have issues, I assume they stay warm enough while running moisture is not a problem, all of them will work if run for a while and warmed up then restarted, if I ever get the time I will tear the worst one down and coat the insides of the inverter with dope and see if that helps.

That makes sense since mine was running that the heat kept it from building up moisture.

 

[FloridaAKM]

I picked up a MEP-831A this morning with 54.5 hours on it that has been thru reset, but there is no fuel in it & the battery is dry of sulfuric acid(actually new). After filling the fluids (oil is clean) I will report back here as to how it runs or doesn't. Thanks for all the info as to what I needed to look for in a unit even though I did go thru the TM's for it.

26 June 2021. Sorry it took so long, but other things get in the way of things I want to work on. I mixed up sulfuric acid & filled the battery & charged it. The battery works great even though is is not factory fresh-contrary to popular belief. It has been raining here every day for almost two weeks, so nothing is dry. The generator sits on a generator trailer & is covered up with the rubber military tarps, so it should be dry, but typical of Florida, the inside had much moisture in it when opened.

After checking fluids & stuff, the generator was started with no hesitation after sitting for a long time @ auction stored outside. The power came up & within seconds tripped out on a fault of short/overload. I let it run for about 15 minutes & shut it down to allow it to dry out from the heat of running. After an hour, it was cranked back up & still no power, but it ran. Left it running for another 15 minutes & shut it off to dry more.

Two hours later, I cranked it back up & behold, there is power. Adding a 1500w load to the convenience outlet showed that it was producing power & all was good. Since it is getting ready to rain again, everything was put back up & covered for the next rainstorm. The oil needs to be brought up to the full mark & it will be ready to take care of the house necessities if we have another hurricane & no power situation. No, it is not perfect, but it fills another bucket list item I wanted.

 

[FloridaAKM]

Since I retired I started working on things around the property more in earnest than normally. I uncovered the M-831 & went to crank it & all the fans & pumps worked fine but the starter wouldn't even clip or chatter. The battery was hooked up to a 7 amp charger & charged for a few hours. After that. the voltage was tested & found to be 23.86 vdc. When the generator was attempted to be started, it would run the fans & pumps, but not start; just click away on the starter.

The battery was removed from the enclosure & put on a different charger as it was boiling acid out of the caps on some of the cells & I didn't want the acid to eat up the generator. A few more hours on the charger just got the battery hot & boil out more acid, so the charger was removed & the battery was left to cool off. This morning, the voltage was checked & it is still 23.85 vdc, so I guess the old adage about you can't let a battery sit to long in its dry state or it will go bad it true. There is no way I will spend $300.00 on another military battery, instead, just make a nato male plug & jump the unit off of one of my trucks or a jump cart!

What say your learned experts on these 24volt lead /acid batteries?

 

[DieselAddict]

I use a pair of motorcycle batteries in series. A much less expensive solution.

 

[kloppk]

I use a pair of motorcycle batteries in series. A much less expensive solution.

Same here in both of my 831's

 

[FloridaAKM]

If you don't mind, which size motorcycle batteries did you buy to put in place of the OEM 24v unit?

 

[DieselAddict]

You can see the batteries and how they look in stalled here - https://www.steelsoldiers.com/threads/mep-831a-troubleshooting.134803/page-4#post-1667559

 

[kloppk]

If you don't mind, which size motorcycle batteries did you buy to put in place of the OEM 24v unit?

In my 831's I installed 17.5 AH 310 CCA AGM's
These.. --> Batteries Plus Battery

 

[FloridaAKM]

I checked on those batteries last night & they would cost me $280.00 plus taxes, so I am back in the same ball park as with the battery that came with the generator. I guess since I have a M-701a with a new military battery in it; I will just move the battery over to the M-831 & jump the M-701 with a jump cart..
The M-701 is either single or three phase & I need three phase to run the A/C - heater in the shop the I got from Gov Planet last year. I hope 3 Kw 3 phase will run a 10K btu a/c.

 

[DieselAddict]

Search Home Depot for YTX20L-BS and their compatible battery is like $60 each.

They will ship them directly to your door.

 

[FloridaAKM]

Excellent, thank you very much for that info!

 

[SurplusIronTherapy]

You can see the batteries and how they look in stalled here - https://www.steelsoldiers.com/threads/mep-831a-troubleshooting.134803/page-4#post-1667559

Thanks for pictures of batteries installed in series. Do you know the gage of the OEM battery cables (my MEP-831A is stored at camp so unable to look directly)? Want to get the correct size ring terminals.

 

[kloppk]

The cables a 6 gauge. I used these terminals. Picked them up in the electrical department at Lowes.