Numerous first timer "pre-buy" questions, can I get some help?

[OffgridIdaho]

Hi and welcome from N Idaho!

I watched the OR auction today and wanted to buy 1 of two gensets up for auction. Gen 1 was an 831 air cooled yanmar and gen 2 was an 802a water cooled onan. Gen will be used to charge my homemade Idaho power wall from LifePo4 EV cells. I currently charge at 40a/24 v or 1390w. I am upgrading my battery and solar in the spring so that charge number will go to 1400w/48v maybe a bit higher.

The questions:

Would a water cooled last longer? Temps here range from -25f-103f

When the ad says "engine not complete" but I see nothing missing what does that mean?
(battery? fuel? water?)

How much fuel per hour would an 831, 802a, 803a use at those amps/watts?

What is the likelihood of getting a dead generator that I have to fix or cannot fix?

Currently I use a Honda 3k pure sine, are the above gensets going to give me a clean wave or garbage? Will the gen pass through bad waves while charging and transfer is going to house?

If I do get a non-running genset what are the chances I CAN fix it? Are parts available to civis? I have been doing my own mech work for 50 years.

How many hours are the air/water cooled good for? Mean time failure hours?

How loud are they at 1500w load?

When bidding, am I better off buying a gen that has 1,000hrs/13yrs old or 21hrs/13 yrs old? Is a gen that got run more often better then one that sat for a decade and not run?

OK thats it for now...........

The results of todays "watch"

I saw a not complete non tested 2003-831 with 125hrs go for $1100 and an 2009-803a with 21hrs go for $3400 +15% commission +driving+fuel+time

Is that good or not good?

 

[Scoobyshep]

greetings and welcome to the fun

1. not sure tbh

2 somethings missing it can be as simple as a battery or larger, you have to look close at the pics

3 load dependant, for these sizes id say no more than 1 gallon per hour but dont quote me

4 anything can be fixed with enough money and patience, usually there is a good chance of getting something runable with minimal effort

5 the 802 and 803 are brushless gen heads so clean wave. i dont have enough hands on with an 831 to tell

6 there are parts available, may take some looking but most things can be obtained

7 there is a overhaul hour point ( i dont know it off the top of my head) but its like a car, good care and they will last for quite a bit

8 I have a 004 and 003, (70s - 80s) and they sat for a bit both took minimal work to get going. heres the thing also to think about with hours. the meters can be replaced and not reflected in the actual unit soo take the hour readings with a grain of salt.


Also watch the pictures for the nameplate its not unheard of to have a listing with the wrong number. you dont want to end up with a 400 hz unit


Hopefully you find some of this helpful

 

[OffgridIdaho]

What should a ballpark price be for an 802/803 genset? Should I shy away from an 831?
Would the 803 be overkill and wasting gas?

Occasionally, while charging at 40a/24v and maybe running the 700w microwave on transfer the chest freezer can kick on drawing 23a/110v peak amps and settle at .8a/110v. Also under same scenario and while charging the well pump kicks on 10a/110v and 10a peak/run.

 

[Scoobyshep]

What should a ballpark price be for an 802/803 genset? Should I shy away from an 831?
Would the 803 be overkill and wasting gas?

Occasionally, while charging at 40a/24v and maybe running the 700w microwave on transfer the chest freezer can kick on drawing 23a/110v peak amps and settle at .8a/110v. Also under same scenario and while charging the well pump kicks on 10a/110v and 10a peak/run.

You should size based on the load, If you dont get these things to run around 50 to 80% rated load they will start wetstacking (buildup of unburnt fuel gunk in the exhaust, and eventually the head) which can be cleaned out by some good heavy loaded running. The ones I selected were more based on availability at the time. The 831 can be a great unit, I just dont have any hands on so I cant provide you any good info on them.

Need a good load calculation to tell what size for sure you need. another factor, these arent like consumer sets where 10000 watt is the starting rating. 10000 means 10000 and sometimes 12000. these sets are built like a brick out house.

 

[OffgridIdaho]

OK thanks, thats good info.

So, currently Im pulling 12a/120v and that will go to 20-24a/120v when I upgrade. Would the 802a be at 50% with those loads?

 

[DieselAddict]

Quick question, What is the motivation for changing to a diesel generator?

What is your current experience with the EU3000? Is it not getting the job done?

 

[OffgridIdaho]

Quick question, What is the motivation for changing to a diesel generator?

What is your current experience with the EU3000? Is it not getting the job done?

The 3000 is rated at 23a at 100% . Im upgrading solar this spring to 48v and doubling battery size and doubling charge rate to 100% gen output, no reserve for other devices to start.
Im currently charging at 12a 50%. If my well pump kicks on im at 100%. If then my chest freezer kicks on im at 200%.

I run all winter on generator, sun is below trees and clouds for the most part. Putting 800-1000hrs per year on genset. Hondas good for 3khrs. Will wear 2800 dollar gen out in 3yrs. Almost 1000/yr in gen cost.

I wont even go off on the zombie apocalypse diesel stores longer and will be more available bs.

Meps last 10x as long?

 

[FarmingSmallKubota]

Do you have the ability or equipment to move the generator. 802a weighs 800 pounds 803a 1100 pounds. Also 831 i think is only rated for 3000 hours before overhaul

 

[OffgridIdaho]

Do you have the ability or equipment to move the generator. 802a weighs 800 pounds 803a 1100 pounds. Also 831 i think is only rated for 3000 hours before overhaul

Ill bribe my neighbor with some fresh butchered red wattle, he has big toys. I only need to move it one time.

 

[DieselAddict]

The 3000 is rated at 23a at 100% . Im upgrading solar this spring to 48v and doubling battery size and doubling charge rate to 100% gen output, no reserve for other devices to start.
Im currently charging at 12a 50%. If my well pump kicks on im at 100%. If then my chest freezer kicks on im at 200%.

I run all winter on generator, sun is below trees and clouds for the most part. Putting 800-1000hrs per year on genset. Hondas good for 3khrs. Will wear 2800 dollar gen out in 3yrs. Almost 1000/yr in gen cost.

Meps last 10x as long?

That is good info. First, MEPs don't last 30k/hrs. Like any machine they do break and they do wear out. The engine in a MEP802 has long life potential, but not knowing how it will be treated or the initial condition of the set, I'd guess that 10khrs is what you should expect to get. Could you get more? Sure. I'd plan for a water pump failure ever 5khrs or so.

Based on what you are saying I would suggest against a MEP831. I love these little generators but if I'm being honest, they are not as reliable as their larger siblings.

My larger concern is if you will be able to load it sufficient to keep it in good shape. Having 20A of load @ 120v totally rules out an MEP803. You'd kill it in no time. Running one at even 50% will cause the exhaust to load up over time.

Assuming a MEP802, you will want the set to spend some time in the 35-40 amp output range @ 120v. Are you going to be able to get there with your setup? By "some time" I would define that as an hour continuous after running under 50% load for 10 or more hours.

 

[OffgridIdaho]

That is good info. First, MEPs don't last 30k/hrs. Like any machine they do break and they do wear out. The engine in a MEP802 has long life potential, but not knowing how it will be treated or the initial condition of the set, I'd guess that 10khrs is what you should expect to get. Could you get more? Sure. I'd plan for a water pump failure ever 5khrs or so.

Based on what you are saying I would suggest against a MEP831. I love these little generators but if I'm being honest, they are not as reliable as their larger siblings.

My larger concern is if you will be able to load it sufficient to keep it in good shape. Having 20A of load @ 120v totally rules out an MEP803. You'd kill it in no time. Running one at even 50% will cause the exhaust to load up over time.

Assuming a MEP802, you will want the set to spend some time in the 35-40 amp output range @ 120v. Are you going to be able to get there with your setup? By "some time" I would define that as an hour continuous after running under 50% load for 10 or more hours.

Thanks for the 411!

I am so glad I didnt bid on the 10k 803.

Im scratching my head as to how I can pull 40a. I have a 1 bdrm cabin off grid built around being self sufficient.

Maybe I can mine bitcoins with a server array while charging?

 

[DieselAddict]

How much battery capacity will you have?

My Schneider inverters have battery chargers built in but I'm considering not using them when I build my final config. Reason why is the inverter will pass through the generator power to loads and use any excess to charge batteries. They use the same transistors to either invert or to charge batteries. They can't charge AND invert simultaneously. This isn't the best use of the generator capacity since any imbalance between phases results in reduced charging current. I'm running 240v split phase by the way. What I want is to bring a generator on to charge batteries and apply a steady 80% load to it. That seems to be about the middle of the sweet spot for engine health and power to fuel efficiency.

To accomplish that I'm considering buying a "cheap" inverter/charger to use for charging only. One of the cheap inverters costs less than a grand which is less than buying a stand-alone charger. With that setup I can apply a constant load on the generator to charge batteries while keeping all the loads in the house on inverter power.

Sounds complicated but its cheaper (for me) to buy a charger that lets me optimize the generator load than it does to replace/repair generators.

On a side note, there is someone that I know that is looking to repurpose the Engine/Permanent Magnet Alternator setup in a MEP831 to use as a battery charger. If that were to work it could change the calculus completely. Its the inverter that is the weak point in the system. The engine in the MEP831 is reliable. Eliminating those parts and taking power directly off the PMA through a charge controller would be a super sweet setup that I expect would be a bullseye for your needs capacity wise.

Sorry for all the rambling. I'm going to stop now.

 

[OffgridIdaho]

How much battery capacity will you have?

My Schneider inverters have battery chargers built in but I'm considering not using them when I build my final config. Reason why is the inverter will pass through the generator power to loads and use any excess to charge batteries. They use the same transistors to either invert or to charge batteries. They can't charge AND invert simultaneously. This isn't the best use of the generator capacity since any imbalance between phases results in reduced charging current. I'm running 240v split phase by the way. What I want is to bring a generator on to charge batteries and apply a steady 80% load to it. That seems to be about the middle of the sweet spot for engine health and power to fuel efficiency.

To accomplish that I'm considering buying a "cheap" inverter/charger to use for charging only. One of the cheap inverters costs less than a grand which is less than buying a stand-alone charger. With that setup I can apply a constant load on the generator to charge batteries while keeping all the loads in the house on inverter power.

Sounds complicated but its cheaper (for me) to buy a charger that lets me optimize the generator load than it does to replace/repair generators.

On a side note, there is someone that I know that is looking to repurpose the Engine/Permanent Magnet Alternator setup in a MEP831 to use as a battery charger. If that were to work it could change the calculus completely. Its the inverter that is the weak point in the system. The engine in the MEP831 is reliable. Eliminating those parts and taking power directly off the PMA through a charge controller would be a super sweet setup that I expect would be a bullseye for your needs capacity wise.

Sorry for all the rambling. I'm going to stop now.

I run Victron. I think it does what you want.

2 shore powers in.
Can run transfer
Can pull from battery while charging

Victron Quattro 48/10000 | 48V Input | 10000VA Output 120V | 140A Charger | Transfer Switch

Signature Solar provides solar panels, off-grid solar systems, grid-tie, and hybrid systems. Quality solar inverters, bifacial solar panels, complete solar kits, solar batteries. Featuring brands such as EG4 Electronics with their solar battery, LifePower4 and EG4 LLifePower4 and EG4 LL

signaturesolar.com

How much amps do you need for your battery and what voltage?

 

[DieselAddict]

I have about 40 kw/hr of battery now. I have another 30 kw/hr of battery on standby to add to the system. Its 48v.

When I build the house the plan is to have 100 to 120 kw/hr of battery power. The inverters are a pair of Schneider 6848s.

One of the cheap inverter/chargers will fully load a MEP802 which is perfect.

 

[OffgridIdaho]

I have about 40 kw/hr of battery now. I have another 30 kw/hr of battery on standby to add to the system. Its 48v.

When I build the house the plan is to have 100 to 120 kw/hr of battery power. The inverters are a pair of Schneider 6848s.

One of the cheap inverter/chargers will fully load a MEP802 which is perfect.

What type of batteries? I built a 13kw LifePo4 pack with grade A NEW EV packs. Delta on batteries fully charged is .001. I have never seen such a balanced pack before. I run a JK BMS which balances at 2a and keeps the batteries in perfect match.

(Version 3) - EVE LF280K Grade A Cells - LiFePO4 Battery

Now with 8,000 cycle life and testing much higher than 280Ah, most all test above 300Ah. Cells include the double hole terminal block welded factory direct by EVE and Flexible busbars. Offered per cell BRAND NEW, GRADE A EVE LF280K CELLS (Version 3) Matching Voltage, Capacity, Internal...

www.18650batterystore.com

 

[DieselAddict]

The 40kw/hr are batteries from a Chevy Volt (3 of them actually) with a Batrium BMS setup.

The new batteries are LiFE 5kw/hr rack mount modules.

 

[OffgridIdaho]

The 40kw/hr are batteries from a Chevy Volt (3 of them actually) with a Batrium BMS setup.

The new batteries are LiFE 5kw/hr rack mount modules.

I built my 13kw for $2300. Looked at rack batteries, grade B genfung batteries at 3x the price of mine.
My first 24v "tester" pack to make sure the batteries were solid and GTG.


This guy on youtube has tested every battery and solar system out there. He said this was the best rack mount.

 

[Daybreak]

Here is a member which put up a bunch of video's off grid with his MEP-802A.
Noble Country - YouTube

 

[robertsears1]

If you get a MEP 802, make sure the exhaust flap on top is present. No flap is almost always a precursor for large problems due to rainwater getting inside the engine And sitting for who knows how long.