gas generator powering a home computer

everlandfarmeverlandfarm Registered Users Posts: 5
Hi Folks,

Newbie, first post. Retired Engineer (I&C), own a farm which experiences up to 7 day power outages during ice storms, SE Ohio.

I initially was interested in setting up an inverter, batteries, solar "maintenance charger," for use during the outages to power an upright freezer. Load is 1200W starting, 140W steady state. Value were determined with a clamp on ammeter at the load center. The "bulk" DC would be provide by an idling farm tractor (12VDC from the alternator) to power the inverter and charge the batteries. Oh, the solar charger would be simply to keep the batteries charged during non use times. Obviously keeping the batteries on a trickle or maintenance charge for extended periods isn't the preferred way to go.

We have experienced these 7 days outages twice in the 5 years since we moved here, so odds are it'll happen again this winter or next at the outside.

The more I looked at the cost for all the components, the more I realized that you "can't be a little bit solar" any more than you can be a little bit pregnant. Particuarly looking at the previously mentioned load I'd be initially setting up for.

I'm fortunate in that my electricity cost is usually $70/month and Ohio is not a "net metering" (if that's the term?) state where you can sell electricity back to the utility. Well, you can, but they reimburse you 4-7% of what you pay for it. AND you have to pay them to put in a special meter to monitor it.

So doing a pretty straight forward cost benefit analysis, I decided that I would simply get a gas generator. I've decided on a Generac GP3250, $449 all over the web and free shipping.

My question is, does anyone have any experience running a home computer powered by a gas generator? I know a UPS would be the way to go, but have talked to people who had problems with a UPS on a generator as the voltage and frequency varied and it shut off. Discarding the UPS, they powered the computer directly off the generator and it worked fine. My experience with "home" computers is that they generally have a pretty "forgiving" tolerance for power, given that the electrical environment we live with isn't as pure as we think it is. I'm talking about brownouts, surges, outages, and other electrical pertubations.

BTW, I'm not one of the "bad guys," in fact I have a meeting tomorrow with a Phd at Ohio University, Athens, who has a grant to study and quantify the wind power availability in the southern part of the state. The wind resource maps indicate that we have an availability of 0-1 on a scale of 10! Grade elevation at my house is 817' and we have wind-lots of it!! There's a 100' tower behind my barn which is used by the local ISP for providing high speed internet to us rural folks. I've offered that as a place to hang necessary monitoring equipment and the internet connection is obviously there for uploading data. It is also used as a relay point for the HAM operators in a 3 county area, and as such is part of the EMS system-Think Hurricane Katrina when all the cell towers went down.

Sorry to be so wordy, but belong to a few forums and wanted to put "my view of reality" out there rather than simply asking the question and then providing bits and pieces for several days. You folks now enjoy the same level of confusion that I enjoy.

Be well,

Ev

Comments

  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: gas generator powering a home computer

    a generator does have its drawbacks with noise in addition to fuel availability and its costs. it should work ok though. as far as the ups goes you may wish to find out which ones are specifically doing that that it won't work well with the generator. a generator is the cheaper route to take for the place that experiences that rare outage.
    as to the solar system you had thought of, you could've used an inverter/charger and batteries via the grid for charging and no pvs are required if you do not wish to have them, but during 7 day outages there would be a problem as this would need the grid to come back on before the batteries fall below 50%. that would be a big battery bank!
    btw, did you already buy the generator as i've got a 4kw generac i'll let go that has less than 25hrs on it and a 10 gallon tank. it does not have wheels and is very heavy and that's why i'd get rid of it as i can't be moving this thing around anymore. you would have to come get it and i'm not too terribly far from you as i'm in pittsburgh. make me a reasonable offer via pm if you're interested.
  • blackswan555blackswan555 Solar Expert Posts: 246 ✭✭
    Re: gas generator powering a home computer

    I would without doubt go the generator route, For the price of them these days even maybe two, One as a spare, The one thing to keep an eye on (I am the other side of the pond, I am presuming Gas is Petrol ?) Is that it go`s off, Either drain it off then run gen carb out of fuel, then keep fresh supplies for emergencies, or give it a half hour run and top up with fresh every month or so.
    Have a good one
    Tim
  • everlandfarmeverlandfarm Registered Users Posts: 5
    Re: gas generator powering a home computer

    Thanks Niel, but the one I'm buying has wheels and a handle for moving around. Wheels are a definite necessity as I'm not as young as I used to be. Hey, we're already into Hurricane season, so storms and power outages aren't far behind, advertise that genny and you'll be able to get most of your $$ back if you wait a couple of months.

    Tim, owning a farm I have small and large gas engines all over and am familiar with gas issues. I ususally put "Stabil" a gas additive that stabilizes the gas for up to 6 months ( so they claim) in engnes I'll be trying to start/run during the winter, others, I simply run dry as you suggest.

    No one has specific expereince with a home computer on a gas genny? Intellectually I feel it should work, but would like to hear from folks who have been down that road.

    Ev
  • GreenerPowerGreenerPower Solar Expert Posts: 264 ✭✭✭✭✭✭
    Re: gas generator powering a home computer

    Not using PCs on generator much but familiar with the internals of the power supply side of PCs. Yeah, they are very forgiving with AC generators, just make sure to get the gennie run stable before you plug it in and unlug it before shutting down the gennie to avoid voltage spikes when the engine speed is not stable.

    Yes, using AC generator for backup in your case is best. I would reccommend a gennie with electric start or option to add one later. Those can be easily controlled to be auto start with an automatic transfer switch and an "auto-start" circuitry that can be added on later if a couple of minutes interruption before power back on becomes too inconvenient (kids are watching their favorite TV shows) ... or you can put those on a PC UPS to avoid a few minutes interruption.
    GP
  • mike95490mike95490 Solar Expert Posts: 9,362 ✭✭✭✭✭
    Re: gas generator powering a home computer
    No one has specific expereince with a home computer on a gas genny? Intellectually I feel it should work, but would like to hear from folks who have been down that road.

    It should work OK. Will you be powering other loads at the same time? A big genset to run a 300W computer is overkill.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • sub3marathonmansub3marathonman Solar Expert Posts: 300 ✭✭✭
    Re: gas generator powering a home computer

    Actually, there is another choice besides a gas generator. If you own a Prius, you can have the car do dual function as a generator too. The site is Priups.com if you're interested.

    In fact, I think it has been shown that as a generator the Prius is much more efficient than the generators out there, since it only runs the engine on occasion after the big battery pack (312V) has run down. You can easily get a 1kw inverter to use with it, or actually Richard Factor, the guy at the website, has rigged a 12kw inverter and can run it off of the car.
  • BB.BB. Super Moderators, Administrators Posts: 32,013 admin
    Re: gas generator powering a home computer

    Ev,

    Are you looking for a "generator" backed UPS type function (i.e., you cannot have a power failure during operation) or just backup power for long outages.

    You can setup a Inverter + battery bank for a "large" UPS type function and use the genset (manual or autostart) to provide backup power beyond xx minutes of backup power (size batteries for xx minutes).

    Or, you can simply flip over to a backup genset once the power is out (auto or manual transfer switch plus manual/auto generator start). And, if practical, use a laptop computer as it has a nice internal battery for an hour or more of backup power built in (plus laptops are designed for low power operation--always a good idea for emergency power/off grid/conservation).

    Computers are pretty frequency tolerant--they just convert the incoming AC power into high voltage DC for down conversion to 1.8/5/12/etc. volt usage.

    Regarding the genset, I would spend the $900 for a Honda eu2000i Inverter/Generator (1,600 watt rated). It has an internal sine wave inverter for rock solid AC power (accurate voltage and frequency).

    The problem with most gensets is that they do not scale down fuel usage when their loads are below 50%... So, lets assume that the Generac is a 3kW unit that gets around 5.5 kWhrs per gallon of fuel and its 50% rating is 1.5 kW watts. fuel usage for 7 days (24 hours per day) will be:

    3kW * 0.50 load * 1/5.5 kWhrs per gallon * 24 hours * 7 days = 46 gallons of fuel.

    The Honda eu2000i actually scales down on fuel usage to below 25% of rated power (and probaby even lower--but I don't have any data for that) and uses about 5.45 kWhrs per gallon of fuel (15 hours, 1.1 gallon fuel tank at 400 watts or less load):

    1.6 kW * 0.25 load * 1/5.45 gallons per hour * 24 hours * 7 days = 12 gallons of fuel

    If your average load was 3kW*50%=1.5kWatts or larger--the Generac would be as fuel efficient (or possibly even more fuel efficient) vs the Honda.

    For loads at 400 watts or less, the Honda will be hands down more fuel efficient and quieter too (probably more reliable also).

    The Honda has a couple of nice features... One is an "Eco Throttle" mode... It can slow the engine down for light loads (quieter and more fuel efficient) but keep the frequency/voltage at spec. because of the internal inverter. Downside is that for starting loads (fridge, A/C) they may fail to start the first time as the engine has to speed up to handle the starting loads (probably would brown out a PC).

    Also, since the Honda has an internal fuel pump, you can take the fuel cap and put a fitting and fuel hose+inline filter on the cap... The generator will then pull fuel from a 5 gallon gas can for continuous operation (vs refilling the internal 1.1 gallon fuel tank). Very nice for longer power outages. (another feature is that you can parallel two Honda eu2000i gensets together for larger loads).

    I would only buy the Generac as a cheap backup/loaner/high power (for pump, saws, etc.) generator. They generally are way too noisy and don't last very long before something breaks--and use the Honda as the main emergency power genset.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • BB.BB. Super Moderators, Administrators Posts: 32,013 admin
    Re: gas generator powering a home computer

    Regarding the Prius backup--It is a neat solution--however remember that its traction battery bank costs $5,000 for replacement... A cheap $900 genset for long term outages may be more cost effective.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: gas generator powering a home computer

    I have done this for many years prior to getting a decent PV set up and still use the gen for back-up. Furthermore, I'm familiar with farm equipment as well! :D

    I used first a B&S powered 5kW generator. It was noisy and fuel-thirsty. Then I got the Honda eu1000 which was the antithesis of the B&S. Still have both. Plus my new back-up gen, a Honda eu2000. The Hondas deserve the praise they get.

    There was never any problem with the voltage/waveform from any gen running the computer. Computers have quite sophisticated power supplies, and can handle a wide range of V and 'dirty' waveforms. I've had both laptops and towers running thusly; never a problem with either. I do recommend a small UPS device, because sometimes even fuel-efficient generators run out of gas at the worst possible moment.

    You're right not to use the tractor for power: not efficient at all. Big motor/small output compared to any generator. And you can't run anything continuously off a UPS; they aren't made for it.

    For household emergency power you might consider an inverter/battery set up that's constantly recharged from the grid. This could handle critical systems when the grid goes down. The generator could re-charge batteries if it stayed down. Then save your money towards a future solar array. I did that too. :D
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: gas generator powering a home computer

    now i'm confused. were you talking of using the small computer ups with a generator attached to it or were you talking of the generator as being the ups for the computer? i had assumed the small computer ups were giving you problems when a genny was attached to it rather than the utility.
    in any case it is workable either way as long as the turn/off is done properly as was pointed out by green power.
  • sub3marathonmansub3marathonman Solar Expert Posts: 300 ✭✭✭
    Re: gas generator powering a home computer
    BB. wrote: »
    Regarding the Prius backup--It is a neat solution--however remember that its traction battery bank costs $5,000 for replacement... A cheap $900 genset for long term outages may be more cost effective.

    -Bill

    Well, it isn't quite that bad. The traction battery currently cost about $2400 or so from a dealer, and can be had for $500 or so from a junkyard. Of course, you do need to buy the car first.
  • BB.BB. Super Moderators, Administrators Posts: 32,013 admin
    Re: gas generator powering a home computer

    Glad to hear the costs are coming down for the battery pack...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • RandomJoeRandomJoe Solar Expert Posts: 472 ✭✭✭
    Re: gas generator powering a home computer

    I'll echo the suggestion to consider the Honda generators. I bought one a little over year ago for exactly the same reason as you - ice storm outages - and was at first going for something a bit larger, until I added up how much fuel I'd have to have on hand to keep the thing fed. With my power requirements during an outage, for a week's outage switching to the Honda let me drop from needing a small gas station somewhere on hand to a 5 gallon gas can will get me through almost a whole week! Big deal should the gas stations themselves lose power...!

    And it's so quiet! I set it at the far side of the patio (all of 10 feet or so from the patio door) and with the door shut and the unit throttled down - which it does for most loads, even the 800W furnace fan doesn't force it to full speed - I can barely hear it sitting in the room with the door. Go elsewhere in the house - or, especially nice to me, out front in the street - and I can't hear it at all! Generator theft is a big issue during outages, and the thought someone headed down the street won't hear mine is nice.

    I also went ahead and put in a solar system to *mostly* handle my emergency power needs. However, I do have another normal use for it (ham radio bench power) that makes the cost a bit more palatable! (Aside from it being a fun hobby for me.) 540W in solar panels will almost but not quite keep up with the fridge in the winter time, summertime I could keep it on but with very little extra for anything else - of course insolation matters, mine here in Oklahoma is better than many areas of the country. The six Trojan T-105s (660AH @ 12V) will handle the fridge for a couple days without any power input. My plan for an outage is to use the battery bank to run the fridge at night and when I'm gone, then the generator can add back whatever the solar panels are unable to make themselves.
  • icarusicarus Solar Expert Posts: 5,433 ✭✭✭✭
    Re: gas generator powering a home computer

    I have been active in the Prius community for a couple of years as Susan has one. (great car) Most of the people who speak about using an inverter, hook it up to the 12vdc battery which, is IMHO a dumb idea. Using the traction battery is a pretty good idea, EXCEPT for any warrantee issue. I think that Toyota is going to have something to say if you have a 1.5 kw inverter hooked up to your traction battery and that battery croaks within the 150k (mile) battery warrantee.

    For my money, a Honda Eu is a great choice for emergency power at 1/40 the price!

    Tony
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