Time for a new Genny

zozomike · August 2017

When I started this place in Central NM, I opted for a 15KW PTO generator behind my tractor which I could move all over property as needed. But as things have matured this is not needed much anymore, and the primary purpose of generator is back up. And that only in the winter when we get those snow and darkness storms that keep the solar near useless for three days. ( then the NM sun comes home again)
And I have realized that ;
A: winter will come again, and
B: its way dumb to be running a 28 HP tractor just to charge my battery.
In looking for " sizing rules" all over the internet it seemed like I had to have 10 KW, but many here seem to do just fine with much smaller. Ran through all similar posts, and probably confused myself...
So I am thinking the Honda EU300is as the EU2000i seems too small when rated.
So 2800 watts 120 vac 23 amps
Derate for 7200 ft =Prox 25% = 2100 watts
Minus 15% for losses = 1784 w, 14.875 A AC or 82 Amps DC, just a bit lower than max output of the VFX3524
Our AC loads are quite small, the well is a different system that fills 500 gallons of elevated storage when sunny, with a gravity delivery system.
All LED, converted Chest fridge, induction cooktops, ( but in the case of winter storms would cook on the wood cookstove anyway)
Am I looking at this in too simplistic a fashion? Realistically would not be using the generator more than 150 hours per year as I see it, and some of that just to keep it alive...
Thanks for sharing any of your wisdom.

MichaelK · August 2017

What the size of your battery bank? You should base the decision based in part by the maximum charging rate your batteries should take. Do you use L16s? Lets use the Trojan L16 was an example. If not, just plug in the appropriate numbers for you own setup.

Assuming the L16 has a capacity of 370 amphours, and you don't want to charge them at more than 1/8 capacity, then that 370Ah/8=46.25amps. If you battery bank is 24V, you want to charge them at about 29.6VDC, so that's 46.25ampsX29.6V=1369watts. Assuming you only have 85% efficiency from your inverter that's 1369/0.85=1610 watts. Derating that for your altitude that becomes 1610/0.75=2147watts. Assuming that you want reasonable overhead for the generator, running it at only 75% capacity, that works out to be 2863watts. So, a 3000 watt generator should be adequate.

That being said, you want to throw in a little extra for dirty spark plugs, dirty air filter, or extra loads you might run (like a saw), so bump that number up another 500-1000 watts. A 3500 watt Home Depot generator should work for you.

mryimmers · August 2017

When I built my cabin a few years ago I got a Yamaha EF2400 inverter generator, I needed something big enough to run a circular saw, but not too big as I would be using it to power the cabin after. I looked at 2000 watt generators from Honda and Yamaha, but didn't think they would "cut it" with the circular saw. The next size up with Honda is 3000 watt and a lot more money. Yamaha has the 2400 watt and it did the job just fine, I have close to 1000 hrs on it now with no problems, very quiet and good on fuel too.
One "feature" that I didn't realize when I bought it, is that all the controls are on the same side if it matters to you. I keep mine in a box with sliding doors so all controls are behind one door, and the exhaust blows out another sliding door. There are lots of reviews on the net.

zozomike · August 2017

Sorry, I had thought my system specs I set up as signature long ago would show up. Guess not.
So we are off grid,
Array 1 1980w -Flex max 80
Array 2 1590 w- flex max 60
Well array 600w with grundfos sqflex11 to tanks
GB industurial 510 AH battery 24 V
VFX 3525 inverter, but something went wrong with the circuit board and the mate wont connect. ( on my list)
DHW by flat plate collectors with large tank per Build it solar plan
Wood cook stove back up to induction and convection cooking. Direct gain passive solar building design.
No propane on property any more. Not quite finished with the new house but living in an adjacent building. Most of the last ten years
have been spent working out of state, so the systems have had to self sustain and done pretty well. Plan to retire to here in Ja 2018 and
finish everything!

zozomike · August 2017

MichaelK thanks for the clear analysis. Based on those numbers it looks like the EU3000i would be a bit small. As you suggest. Running those I come up with 2950w . Might work the EU3000i too hard?

Estragon · August 2017

If you find the generator is faulting with overload, you can set max charging current lower on the vfx. I do that when charging with a little eu2000. Normally I bulk with a 4kw diesel, but can use the honda in a pinch by adjusting Outbacks.

You'd need to get the mate going to change settings though.

zozomike · August 2017

Yes on the Mate, thanks. That may be a solution to using the EU3000is. Several years ago when I added the Mate, got it all set up and while tidying the wiring, I think the connection on the circuit board of the inverter fried. So I have been without a Mate, ( in more ways than one) Inverter still works great so have not been home enough to address that issue, and do not know how I would with only one inverter... The mate is on the controllers now, so is of limited use. And absences have been so extended working out of state, that I have to re-learn everything solar when I have a bit of home time. Damn memory went the same time the brown left my hair.

jonr · August 2017

I believe that two EU2000is in parallel is the same price. And more flexible in terms of shutting one off during absorb. And provides redundancy. But if possible, I'd buy just use one and tolerate slower charging.

mike95490 · August 2017

The inverter generators are a bit of price overkill for charging batteries. And charging batteries is quite demanding for generators, it's a solid heavy load with no letup, for hours. You have to check the PF rating of your charger and make sure your generator has enough overhead to cope with the PF and any odd loads that come on line when charging,
Too bad other generators won't install quiet mufflers like the inverters have,

zozomike · August 2017

jonr seems like the pair is a couple of hundred higher. BUT can deliver 400 more watts. Which would put me more in comfort range using Michael Ks methodology I would need 2950w before any loads.
Never gave serious consideration to a pair of EU2000is. Seems like double the fueling, double the parts etc. BUT, redundancy is a big plus. Per your idea to just use one, I can tolerate slower charging, can the system? Outback seems to give MAX specs but not much said about minimums. I figure to use a smaller one I would have to buy a new inverter, so I could use the Mate, and send the existing to Outback for repairs to have that as backup.
That said the idea of one quiet little generator is way appealing.
And yes mike95490, inverter generators are pricey. At this stage of having worked 84+ hours per week for the last year and half. I want reliability, not something I have to mess with.

Estragon · August 2017

Using an eu2000, you could set the limit at around 40-50a, which isn't a bad rate of charge into a 510ah bank. 50a times 28v charging = 1400w, which the eu2000 should handle. When you get to absorb, you could put it in eco mode to save gas and run quieter.

There's really no minimum charge current needed. It just takes longer to bulk charge with a lower max.

zozomike · August 2017

Thanks Estragon. I think I have a plan now due to everyone's help. Going to, as I mentioned earlier, order a replacement inverter so I can use my Mate. Send the old for repairs. Start with the EU2000i and if too limited, add the companion later.

mryimmers · August 2017

FYI, Yamaha has a new model, the EF2000iST, that allows you to twin 2 generators together like Honda does.

zozomike · August 2017

Looks like direct competition for the EU20001. Did not know about this one. And the combo kits cheaper. In the states seems to be labeled

EF2000ISV2. Decisions, decisions, red or blue?

westbranch · August 2017

I have some of both brand, 3 Honda, 1 Yamaha, 2 Husquavarna and 1 Echo. treat them all the same, OPTI-4, Premium gas if available, Seafoam [or OPTI-2 @ 100:1 for 2 cycle stuff..]
local dealer is about the only item you do not control... &/or operator error...

Time for a new Genny

Comments

EF2000ISV2. Decisions, decisions, red or blue?

Categories