Couple of questions on a MEP831a

NotPants

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I stumbled onto a local guy who has a MEP831a for sale. 7 hours on the clock. Looks super clean inside and out. No sun damage/dings/dents/oil. $1500

I'm comfortable with electronics and wiring but never touched a diesel engine.

I want the unit as a whole house backup / emergency unit. The next comparable commercial unit is about 4,000 bucks (I want 220 output / pure sine)


Just curious what your thoughts are... is 1500 too much? Will I be in over my head trying to source parts, etc?
 

Demoh

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St Pete, FL
Well I havent hooked up a scope to these units, they are inverter generators rated at 3kw, I doubt pure sine.

Priced like that I would hope its been gone through, all rubber replaced, not just fluids and filters. If its just fluids and filters Id say its overpriced, but thats my opinion. I sell them for more but everything is gone through, all hoses / rubber replaced, load banked, governor controller replaced, batteries, (basically a full overhaul) but it is a get what you pay for type of thing. Sometimes you will get a unit that looks and runs great that is low hours, but find that after a few dozen hours starts to leak because the 10 year old rubber that you are now asking to hold fluids just isnt ready for that.

The bigger question is for a whole house backup, unless you live in an RV or have a SUPER efficient house, it will likely not be big enough. Tell us about your house, your big loads, and what you are going to look to run. Commonly the 802a and 803a is what people run for house backup.
 

NotPants

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Well I havent hooked up a scope to these units, they are inverter generators rated at 3kw, I doubt pure sine.

Priced like that I would hope its been gone through, all rubber replaced, not just fluids and filters. If its just fluids and filters Id say its overpriced, but thats my opinion. I sell them for more but everything is gone through, all hoses / rubber replaced, load banked, governor controller replaced, batteries, (basically a full overhaul) but it is a get what you pay for type of thing. Sometimes you will get a unit that looks and runs great that is low hours, but find that after a few dozen hours starts to leak because the 10 year old rubber that you are now asking to hold fluids just isnt ready for that.

The bigger question is for a whole house backup, unless you live in an RV or have a SUPER efficient house, it will likely not be big enough. Tell us about your house, your big loads, and what you are going to look to run. Commonly the 802a and 803a is what people run for house backup.
I'm OK with making a bit of a project out of it and going through the hoses and rubber parts.

3kw is plenty for me. Small house, just me. At most I'd want to run the furnace blower, some lights, modem/router/laptop. Not a huge amount of stuff running and I'm on all gas appliances.
 

Demoh

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St Pete, FL
With my testing with the 831 they dont like motor loads due to the startup current. While I did not have an AC blower to test because the house I was testing at was an inverter multizone mini split system, some motors that were tried were small bench grinder, chop saw, garbage disposal. All 3 of those would trip the generator short circuit safety which basically means it will not run it.

Get the blower RLA and LRA ratings. We have to make sure the LRA is lower than the short circuit set point.

During michael we had an 831 on an RV with a rooftop ac unit that running was 2kw on the unit (120v only operation) and startup must have been under the short circuit trip of these generators. Anything bigger than that unit im afraid it will not start without a soft start controller.

The 831s are great fuel efficient units if you can get your ac/heat fan/compressor started.
 

gstirling

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i have 831, it is fairly quite, fuel efficient, I have used it to run a 7 in. circular saw, block heater and lights out in a remote shed for my 936 (not all at once). as stated above it is a little on the small side for "whole" house and would recommend looking at the 5 or 10 kw units. it will not run even my very small air compressor. inrush current trips the overload. so i doubt it will run a house well pump. i got mine direct from uncle sam, it needed new batteries (i used two motorcycle batteries as the cheapest option), filter, and the governor was bad on mine, strongly suggest you replace it with the solid state one sold here on steel soldiers (much better than OEM part). The weak point of these machines is the inverter... if it fails you're done, as last time i checked around they are very.. very hard to find. The engines seem to be great and parts are available all day long.
 

gstirling

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and 1500$ is average going rate for a good one, they have been going up at the auction sites. also if it has the solar charger - nice extra.
 

Bmxenbrett

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Westighouse and champion sell inverter based 4k and 3.5k generators with prety good fuel burn number for $600 and $500. Have you looked at them?

Also at $1500 and 3kw your prety darn close to buying a brand spanken new honda inverter.

Sometimes these meps mak sence some times they dont. In the recent years there price had gone up so to me they dont make sence. Meps now are priced just below new Yanmar generators.
 

Bmxenbrett

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240v in a inverter generator..you will be hard pressed to find a 3kw unit. Why do you need 240v?

The cheap inverter generators have come a long way in the last few years. Champion are cheap for a reason but its $1k and 2x the output of the used 831 your looking at.
 

gstirling

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Dav5 - good to know, i have a 240 3/4 hp deep well, never tried it on my 831 (need to do the math but bet it exceeds 3kw inrush current ability), because when it hits my 14kw generac generator it notices the load at start. my 831 will run a dewalt 7 1/2 circular saw with no issues plus a box fan. max capacity (on gauge) it will handle 2 1500w space heaters (how i tested 100% resistive full load), but not my 2 hp air compressor.
 

dav5

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I manage loads and switch between the pump and water heater. I took Dieseladdicts advice and replaced the 3500W elements with 3000W elements. I replaced the OEM controller with one of Kurts controllers. I don't think it would have run the pump with the original controller. Kurts controllers are fantastic.
I really like my camp setup but for full time use at home I went with an 803A. For the limited demand in this case the 802A would be ideal with probably no need for load management.
 

Demoh

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St Pete, FL
Weird that it couldn't spin up a bench grinder. The 831 must not have much in terms of peak/burst power?
It all comes down to the surge being lower than the setpoint on the gen. There were some motors that the gen had no problem starting, but there were some that I was dumbfounded on why it wouldnt start. 3/4hp garbarge disposal and the chop saw I expected not to start, but I expected it to run the bench grinder, but its a cheap unit that takes FOREVER to spin up (so its pretty much a short for a long time). With the 7in circular saw that gstirling had was probably a better design than the bench grinder I had because I can almost guarantee that motor is bigger than the bench grinder.

It ran every fridge, freezer, RV air conditioner that we threw at it. Even ran the heatpump water heater (basically a 240v fridge) without issue. Only point im making is you have to be careful with motor loads. The peak power is in the manual somewhere and I dont remember what the actual rating is.



Once Im done with my projects and Kurt is done with his we are going to get a firmware going for an 831 with an actual 120/240 60hz genhead which im going to test the crap out of side by side with my inverter 831s. (I have a unit with a bad inverter) I predict surge loads would be handled better with this at the expense of fuel economy due to 100% 3600RPM instead of the variable with the inverter. But hey, for people who's inverter went out this is a lot better option than scrapping the unit.
 

DieselAddict

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Why 240? Easier to feed the house.
Here is why I got started down this rabbit hole.

I was originally interested in the 831 due to it offering 240v. I wanted an efficient generator that could start my well pump which is 240v. When we loose power here the main pain point is loosing water. The Honda inverter generators I have do well on fuel consumption but are 120v only.

Where I live power outages are rarely measured in hours. They are normally measured in days.

Add to that my car and truck being diesel I have a LOT of diesel fuel available at any point in time. Having fewer fuels in storage simplifies things significantly. Not to mention the longer shelf life (in general) offered by diesel.

Once I started playing around with them I got hooked on them. Thankfully the change from GL to GP and the significant price increase has pretty much brought my addition to an end. Once I sell the few generators I have left I'll not likely buy any more.
 

ATXKMM

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So, apologies but I am reviving this old thread instead of starting a new one since the subject matter is spot on to see what the result ended up being with an MEP-831a and load.

The recent winter storm in TX has made it clear that self sufficiency is more important than ever. I am as much or more concerned that ERCOT is going to fail us in the end of August, and that my friends will be a different story than a winter blackout altogether.

Has anyone ever determined what LRA an 831a might bear? I have put off getting a clamp meter as this is maybe literally the only thing I might use it for. My hope was that the 831a might run a 2.5ton AC unit with a soft-start setup and very careful management of a router, deep freeze and fridge on a transfer switch I could manage manually (or each is on some sort of battery backup to offset the hard-start issue when power is applied). Any phone/computer can charge via a vehicle if its too close to manage in addition to the four items above.

I haven't gone to try to gather the numbers on the appliances as of yet, and they are all able to be sacrificed if necessary, but if it wont manage the AC it's moot anyway. I figure the deep freeze will have enough thermal mass to mostly just coast along anyway but what do I know...

This AC is 2.5T 30K BTU central system (with gas heat). I could also look to see what I could do to lower the startup current by replacing the fan motors with more modern options perhaps, but the soft-start should manage that for me. Please see the pic below for the data plate.

Your thoughts would be greatly appreciated!

ATXKMM


Min Circuit Amps- 17.8@208/230V
Circuit Breaker 30A
Compressor RLA 12.8 and LRA 61.0
FLA adds 1.8

AC DAtaPlate.jpg
 

DieselAddict

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Virtually zero chance of success of it starting the compressor. It may run the fan but thats it. The 831 can't handle a lot of inrush. The inverter will trip out on overload. MEP802 at a minimum. One of those will start my 3T unit.
 
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