help with my generator backup

[jbusch]

We have a off grid cabin in Colorado and up until this year we have been running our cabin on a 12kw LP generac, this year I installed a solar setup. I installed a 4000watt magnum split phase inverter with charge controller, 12 batteries in a 24volt configuration, 8 panels, and AGS, BMK, and a bunch of other expensive parts. Our system runs everything needed but I need to have a generator for backup. Our generator is finally crapped out. I need to replace it asap as our winter needs are struggling right now. I spoke with Generac and there recommendation is the ecosense 6kw system for $3300, it is designed for offgrid applications with 2 wire setups (which is nice), however, I am not necessarily married to that option. Since the generators only job is to charge the batteries I am wondering if a different electric start generator, maybe a portable gas powered option, which is much less expensive would work. It needs to work automatically with the ags so that I don't have to monitor it as this is a second home for us. So, please enlighten me!

[jbusch]

The batteries are 12 Trojan 105, 6V with 675AH capacity

[Logan005]

If I were going to spend that kind of money, I would reconfigure to 48 volt battery bank and add a few extra panels. depending on how old the batteries are, Unless you really need/want the backup generator? Would need to know your demands and usage. I assume you use gas appliances, (stove, heat and hot water) you power a well pump? washing machine? I also have t-105's unless I am mistaken, they are 225ah, 112.5 usable. Your usable AH rating is X3 = 337.5 AH, Try to balance your demands with the solar and battery system you already have. for a cabin I would use a chest refrigerator and a very small microwave oven. Gas range and gas heat and hot water. Led lighting and a stove top coffee pot or press. try to stay away from electric heating elements. You have a nice system a generator is nice to maintain batteries if solar is under sized.

[Sunking]

The batteries are 12 Trojan 105, 6V with 675AH capacity

You are going to be replacing them soon installed in parallel.

Last thing you really want is gasoline. You genny has to be sized not only to charge the batteries, but run everything in the house at the same time. You will even have to run the genny for several days at a time during cloudy weather spells or you go dark. Even a monthly EQ charge can take 12 to 24 hours of generator run time. So last thing you want is gasoline. You cannot store that much and it goes stale fairly quickly. You want LPG or diesel.

3 Kw is way too small based on your battery capacity. It would take that 3 KW just to charge the battery and that would burn up a 3 KW genny running at full power unless it is diesel. It will take at least a 4 Kw genny with 80 amp charger. However you also need extra to run the cabin, so 6 Kw is just about right.

Generac residential genniy's should be avoided. Commercial units are OK. For consumer genny I would look at Kohler models

[jbusch]

Batteries are wired positive to negative. I must be mistaken about the amp hour capacity. Anyways, all appliances are gas, fridge will be switched over to electric in spring. No dishwasher, no washing machine, no microwave oven. We use an instant on hot water heater, all led lighting, counter top espresso machine, fireplace for heat as well as a free standing gas fireplace, but the biggest draw is the well pump, 65 amps only for a short 90 second draw. I am looking at the generac ecogen 6kw as its designed for off grid applications, but mixed reviews. Thoughts? Or alternatives? It needs to work with the auto gen start

[Sunking]

I am looking at the generac ecogen 6kw as its designed for off grid applications, but mixed reviews. Thoughts? Or alternatives? It needs to work with the auto gen start

Already answered, Kohler in the Kw rating you need. Best around for home pad mounts is Cummins but they start at 13 Kw which would work.

Take note any home stationary generator is fueled with either LPG, NG, and Diesel. Diesel is usually only offered in 40 Kw and larger. You do not want Gasoline as that is just for portable light duty generators on wheels.

If money is no object, you want the best, then Lister is the way to go, and they are all Diesel starting with 5 Kva models. Just be sure to name who gets it in your Last Will & Testament. A Lister genny can even be ran on vegetable oil if needed.

[jbusch]

Money is always an object. Yep, reread everything after I posted. Thanks for the feedback. I'll look at kohler. A bit pricey but will see what I can find. Kohler has a utility backup 8kw for around 2k. But it's not designed for off grid. However, neither was our previous unit and we got 14 yrs out of that one

[Sunking]

But it's not designed for off grid.

That is just marketing hype.

[jbusch]

That is just marketing hype.

Thats good to know, it drastically changes the price. So, know an 8kw or even 11kw unit will work within my price range, given that the "off-grid" units are $5k for the kohler unit

[Sunking]

I need to correct myself as there is a difference between Residential and Off-Grid genny's. My Bad..

None of thee manufactures will honor their warranty if you use a Residential Generator on a Off-Grid property. That is because they say their Residential units are not made to run for extended periods of times Off-Grid genny's need to run. In other words the Off-Grid units are built like a Commercial grade units vs Consumer grade.

[Mike90250]

Mike here, running a Lister clone as my prime generator. The 2 year old Robin/Subaru/Hatz diesel genset had 50 hours before the governor crapped out, Oh well. Lister power keeps me going, 10 days so far in the clouds and rain, maybe monday the sun will come out.

Looking for a new genset, look for 1800 rpm, some RV yards will sell used onan 2 - 5 kw gensets pulled from RV's

[Sunking]

Looking for a new genset, look for 1800 rpm, some RV yards will sell used onan 2 - 5 kw gensets pulled from RV's

Dang I forgot about Onan. Good genny's. Well at least the larger commercial series are.

One thing folks do not realize or understand with Off-Grid, consumer grade generators are not going to cut it.

[Bala]

As well as a quality engine its needs to have a quality generator end bolted to it. Now days company's could bolt any cheap generator end on. I went listed. No coolant problems, 10kva, I can run my whole house if need be. They are noisy but I built a silenced room for it. 40,000hr life expectancy. I have done 1600hrs in 10 years.