Question:
Hi; For those that are already using one. For backup power,I wish to run my full size 120volt house fridge on a battery and inverter,so that I do not have to loaf a genny all day. On a sears page there is a fridge that claims 468 kwhs per year. That gives ~ 1.3 kwh hours per day. If the fridge runs ~ 15 minutes per hour,24 hours a day then it is ~ 214 watts. This is small for a inverter except for surge. 214 watts X ~10 for surge = 2000 or 2100 watts surge. Please check my math and reasoning. Are any of you running a full size fridge on a 2000 watt surge inverter ? a gas(Dc charger) should be able to recharge 1.3 kwh quickly(short run time). Thanks Mike PS I do not check the e-mail at the above address
Response:
>Are any of you running a full size fridge on a 2000 watt surge >inverter ?
No, but my Watts Up Pro tells me that three fridges I tested recently measure, in order of age (oldest first): 150W Run, 1,900W Peak (fridge over, non-frost-free) 200W Run, 2,400W+ Peak (SideBySide, icemaker, FF) 200W Run, 2,300W Peak (SideBySide, Icemaker, FF) If that’s really the only thing you want to run on this inverter, I’d make sure it’s rated for 2,500 to 3,000 surge, and has a good warranty.
Response:
>Are any of you running a full size fridge on a 2000 watt surge >inverter ? > No, but my Watts Up Pro tells me that three fridges I tested recently > measure, in order of age (oldest first): > 150W Run, 1,900W Peak (fridge over, non-frost-free) > 200W Run, 2,400W+ Peak (SideBySide, icemaker, FF) > 200W Run, 2,300W Peak (SideBySide, Icemaker, FF)
Did you test them over a 24-hour period? What was their daily consumption? Perhaps it’s just because I live in South Florida, but I think that the 15 minutes/hour assumption made by the origininator of this thread is impossibly optimistic. I have tried this with a 1,200 watt inverter (peak capacity unknown) with mixed results at best. You would need a truly impressive battery bank to make this idea practical. For only occasional power outages, it would be far cheaper to just run an appropriately-sized generator. This would be a great job for an inverter-type generator (but that is also an expensive solution). Vaughn – Hide quoted text — Show quoted text -> If that’s really the only thing you want to run on this inverter, I’d > make sure it’s rated for 2,500 to 3,000 surge, and has a good > warranty.
Response:
> >Are any of you running a full size fridge on a 2000 watt surge >inverter ? > No, but my Watts Up Pro tells me that three fridges I tested recently > measure, in order of age (oldest first): > 150W Run, 1,900W Peak (fridge over, non-frost-free) > 200W Run, 2,400W+ Peak (SideBySide, icemaker, FF) > 200W Run, 2,300W Peak (SideBySide, Icemaker, FF) > If that’s really the only thing you want to run on this inverter, I’d > make sure it’s rated for 2,500 to 3,000 surge, and has a good > warranty.
And 800Ah of battery storage for around five days autonomy
Response:
>> 150W Run, 1,900W Peak (fridge over, non-frost-free) > 200W Run, 2,400W+ Peak (SideBySide, icemaker, FF) > 200W Run, 2,300W Peak (SideBySide, Icemaker, FF) > Did you test them over a 24-hour period? What was their daily consumption?
I tested them over several days. Monthly KWHR averages were {40,25}, 95, and 95. The first one is in my basement in MA, the third one is in my kitchen in MA, and the middle one is in the Turks & Caicos Islands. The {40,25} means that it was running at an average of 40 KWHR/month until a power failure, then it started up again at 25 KWHr/month, yeah very strange…) Duty cycle was {55,20}, 95, and (60+/- 10) percent. Different ages, different technologies, different environments. I’d suggest the OP get a Watts Up Pro and log his actual fridge for a while and then plan either his inverter setup or a new fridge…
Response:
>I tested them over several days. Monthly KWHR averages were {40,25}, >95, and 95. The first one is in my basement in MA, the third one is >in my kitchen in MA, and the middle one is in the Turks & Caicos >Islands. The {40,25} means that it was running at an average of 40 >KWHR/month until a power failure, then it started up again at 25 >KWHr/month, yeah very strange…)
Did it have heater strips in the door frame? These are often used to prevent condensation. They’ve often got a manual switch hidden away somewhere labeled "energy saver" or "humidity control". they, natch, waste plenty of power – both by running and by pumping extra heat into the frame -> the refrig space. Could be that either you flicked the wsitch or that a fused connection/relay/whatever died during the power hit. — Knowledge may be power, but communications is the key [to foil spammers, my address has been double rot-13 encoded]
Response:
> I tested them over several days. Monthly KWHR averages were {40,25}, > 95, and 95. The first one is in my basement in MA, the third one is > in my kitchen in MA, and the middle one is in the Turks & Caicos > Islands. The {40,25} means that it was running at an average of 40 > KWHR/month until a power failure, then it started up again at 25 > KWHr/month, yeah very strange…)
I hear if fridges get frosted up, they actually use more power because the heat exchanging coils are insulated by the ice. Therefore the motor stays on more often. Is it possible that the power failure allowed the fridge to defrost and start working more efficiently?
Response:
> >> 150W Run, 1,900W Peak (fridge over, non-frost-free) … > The {40,25} means that it was running at an average of 40 > KWHR/month until a power failure, then it started up again at 25 > KWHr/month, yeah very strange…)
Perhaps it benefitted from the defrost. I happen to be a huge fan of separated freezer and fridge non-frost-free (or "manual defrost" fridges, because most of my annoying defrost problems have been directly related to "frost-free" (not exactly) units which use one set of coils to cool both the fridge and freezer, so all the fridge water ends up in the freezer. Once a day they heat up the back of the freezer where the cooling coils are – this warms up the food in the back of the freezer, and often does not actually remove the frost in the coils, so you eventually have to tear it all down for a manual defreost anyway – meanwhile, you’re running an electric heater inside the space that you are trying to cool on a regular basis. Your numbers support the idea that automatic defrost (not, obviously, isolated from other differences) sucks a lot of energy; and that doing an occasional manual defrost is indeed worthwhile on a manual defrost fridge. > Duty cycle was {55,20}, 95, and (60+/- 10) percent.
Looks like it from this number, too. — Cats, Coffee, Chocolate…vices to live by
Response:
Thanks for your replies. I intend to recharge the batteries every evening while the Generator(diesel 12kw plus low speed alternator)is running for other loads. 1kwh per day should be easy to recharge. My question is more about a realistic surge requirement. Mike
Response:
>{40,25} means that it was running at an average of 40 >KWHR/month until a power failure, then it started up again at 25 >KWHr/month, yeah very strange…)
A fuzzy plot is at http://compusmiths.com/BasementFridge.gif where you can see that it was doing a very regular cycle before the power failure, with operating power around 100W and peaks aorund 1700W. After the power failure it was operating around 200W, was no longer regular, and peaked out around 2,300W, but since the duty cycle was less than half the previous value, the total power was down significantly. Strangely, the power factor was 1.0 before the power failure and around 0.6 afterwards, maybe something wiped out the power factor correction? Bizarre, anyway. I can post the raw data if anyone wants to download the (free) graphing package from doubleed.com and take a look at it in greater detail.
Response:
>For backup power,I wish to run my full >size 120volt house fridge on a >battery and inverter,so that I do not have >to loaf a genny all day.
Get real. New "energy efficient" mid-size GE refrigerator I recently got is 750W. If you’re going to run a refrigerator on an inverter, what are you going to power lights, computer, microwave, TV, etc. with – or will the power be on for them and just out for the refrigerator? Get a small generator that can power the stuff you can’t live without – and it’ll keep fuel consumption very low. <B>Dissident news – plus immigration, gun rights, weather, Internet Gun Show <I><A HREF="http://www.alamanceind.com">ALAMANCE INDEPENDENT: official newspaper of the Vast Right Wing Conspiracy</A></b></i>
Response:
For some power use comparisons between AC & DC fridges and discussion about some problems running them off inverters, see the FAQ- Fridges at www.rpc.com.au Dave – Hide quoted text — Show quoted text -> Did you test them over a 24-hour period? What was their daily > consumption? > I tested them over several days. Monthly KWHR averages were {40,25}, >. I’d suggest the OP > get a Watts Up Pro and log his actual fridge for a while and then plan > either his inverter setup or a new fridge…
Response:
> Thanks for your replies. > I intend to recharge the batteries every evening while the > Generator(diesel 12kw plus low speed alternator)is running for other > loads. 1kwh per day should be easy to recharge. My question is more > about a realistic surge requirement. > Mike
As a basic rule of thumb the surge could be as high as ten times the run load. This of course depends on many factors. A realistic number can be had if you have a meter designed for the job. Not cheap but not all that expensive either. Will see if I can get you a part number for one. OTOH you could just ask the manufacturer of the fridge. The other way is to take the fridge to the inverter and plug it in. Try before you buy. This is often the best, but with a fridge can be a bit of a job.
Response:
– Hide quoted text — Show quoted text -> >Are any of you running a full size fridge on a 2000 watt surge > >inverter ? > No, but my Watts Up Pro tells me that three fridges I tested recently > measure, in order of age (oldest first): > 150W Run, 1,900W Peak (fridge over, non-frost-free) > 200W Run, 2,400W+ Peak (SideBySide, icemaker, FF) > 200W Run, 2,300W Peak (SideBySide, Icemaker, FF) > If that’s really the only thing you want to run on this inverter, I’d > make sure it’s rated for 2,500 to 3,000 surge, and has a good > warranty. >And 800Ah of battery storage for around five days autonomy
Amp hours independent of voltage…. *again*. As expected, no correction from Smith because he has you plonked. But Nick has either given up hope that you’ll learn, or is on vacation.
Wayne
Response:
>>For backup power,I wish to run my full >size 120volt house fridge on a >battery and inverter,so that I do not have >to loaf a genny all day. > Get real. New "energy efficient" mid-size GE refrigerator I recently got is >750W. If you’re going to run a refrigerator on an inverter, what are you going >to power lights, computer, microwave, TV, etc. with – or will the power be on >for them and just out for the refrigerator? > Get a small generator that can power the stuff you can’t live without – and >it’ll keep fuel consumption very low.
750W? Are you a "solar design consultant" by any chance? :-) Perhaps you mean 750Whrs per day….. If so, then running that from a battery-inverter system is no big deal. If you can find something similar to your GE on this chart, it might be helpful. Lowest (conventional) full size unit seems to be over a kWh per day. Wayne
Response:
>>Are any of you running a full size fridge on a 2000 watt surge >inverter ? >No, but my Watts Up Pro tells me that three fridges I tested recently >measure, in order of age (oldest first): >150W Run, 1,900W Peak (fridge over, non-frost-free) >200W Run, 2,400W+ Peak (SideBySide, icemaker, FF) >200W Run, 2,300W Peak (SideBySide, Icemaker, FF) >If that’s really the only thing you want to run on this inverter, I’d >make sure it’s rated for 2,500 to 3,000 surge, and has a good >warranty.
I just checked ours (Amana BR22 IIRC), 22 cu. ft. bottom freezer. 1.3 Amps running, 12.3 surge. Measured with Fluke 337. To the OP – you might ask the inverter manufacturer to be specific about whether their 2kW surge rating is real-world. Wayne
Response:
– Hide quoted text — Show quoted text ->>For backup power,I wish to run my full >size 120volt house fridge on a >>battery and inverter,so that I do not have >to loaf a genny all day. > Get real. New "energy efficient" mid-size GE refrigerator I recently got is >750W. If you’re going to run a refrigerator on an inverter, what are you going >to power lights, computer, microwave, TV, etc. with – or will the power be on >for them and just out for the refrigerator? > Get a small generator that can power the stuff you can’t live without – and >it’ll keep fuel consumption very low. >750W? Are you a "solar design consultant" by any chance? :-) Perhaps >you mean 750Whrs per day….. If so, then running that from a >battery-inverter system is no big deal. >If you can find something similar to your GE on this chart, it might >be helpful. Lowest (conventional) full size unit seems to be over a >kWh per day. >Wayne
Oops, forgot the link for the chart. http://www.aceee.org/consumerguide/topfridge.htm
Response:
>Newsgroups: alt.energy.homepower >Thanks for your replies. >I intend to recharge the batteries every evening while the >Generator(diesel 12kw plus low speed alternator)is running for other >loads. 1kwh per day should be easy to recharge. My question is more >about a realistic surge requirement. >Mike You might question about recharge time. On my system, an hour’s generator run recharges 80% of the overnight discharge. Most of the rest would take another 2 hours. Then there’s a couple hours’ additional light overcharge for maintenance. On a mediocre solar day my PV’s will usually finish the charge – much more efficient than running the generator at light load. How long is your expected evening gen run? Someone suggested 5 days’ autonomy in your battery capacity. That’s nonsense for your use. Overnight discharge to half capacity should be adequate for back-up service where you recharge each day. To determine surge requirement, I’d measure the locked rotor current draw of the reefer compressor motor. After setting up your ammeter, run compressor for a few minutes, shut off (change thermostat setting), then restart. High gas pressure will stall compressor. Take your reading quickly and shut off, let bleed down a few minutes before restarting. Now you have a number for asking advice from the inverter mfr. Mine is 15 amps. Tom Willmon near Mountainair, (mid) New Mexico, USA Net-Tamer V 1.12.0 – Registered
Response:
– Hide quoted text — Show quoted text ->>>For backup power,I wish to run my full >size 120volt house fridge on a >>>battery and inverter,so that I do not have >to loaf a genny all day. >> Get real. New "energy efficient" mid-size GE refrigerator I recently >> got is >>750W. If you’re going to run a refrigerator on an inverter, what are you >>going >>to power lights, computer, microwave, TV, etc. with – or will the power >>be on >>for them and just out for the refrigerator? >> Get a small generator that can power the stuff you can’t live >> without – and >>it’ll keep fuel consumption very low. >750W? Are you a "solar design consultant" by any chance? :-) Perhaps >you mean 750Whrs per day….. If so, then running that from a >battery-inverter system is no big deal. >If you can find something similar to your GE on this chart, it might >be helpful. Lowest (conventional) full size unit seems to be over a >kWh per day. >Wayne > Oops, forgot the link for the chart. > http://www.aceee.org/consumerguide/topfridge.htm
hi all, just a question really on this topic, could a large capacitor handle the surge, only as i see it it is only a start up surge, not an expert so please tell me where I am wrong. cheers – Hide quoted text — Show quoted text –
Response:
– Hide quoted text — Show quoted text -> Hi; > For those that are already using one. > For backup power,I wish to run my full size 120volt house fridge on a > battery and inverter,so that I do not have to loaf a genny all day. > On a sears page there is a fridge that claims 468 kwhs per year. > That gives ~ 1.3 kwh hours per day. > If the fridge runs ~ 15 minutes per hour,24 hours a day then it is ~ > 214 watts. > This is small for a inverter except for surge. > 214 watts X ~10 for surge = 2000 or 2100 watts surge. > Please check my math and reasoning. > Are any of you running a full size fridge on a 2000 watt surge > inverter ? > a gas(Dc charger) should be able to recharge 1.3 kwh quickly(short run > time). > Thanks > Mike > PS I do not check the e-mail at the above address
WOW your looking at a HUGE UPS. You will have to allow for the startup current which is 6 times running load. Your going to end up with a bank of batteries to store and take care of. Would it not be easier to just start the gen up 2-3 times an hour and if the refer needs to cool it will if not it wont.
Response:
> hi all, just a question really on this topic, could a large capacitor handle > the surge, only as i see it it is only a start up surge, not an expert so > please tell me where I am wrong. cheers
Yes it can, and it is called a BATTERY……. Me
Response:
>hi all, just a question really on this topic, could a large capacitor handle >the surge, only as i see it it is only a start up surge, not an expert so >please tell me where I am wrong. cheers
How dare you try to drag us back on topic! 8*) The battery can handle the startup surge, that’s no problem. The question is whether you will blow the inverter up with repeated current surges. Maybe it’ll just be a bit more heat than it can handle steady-state, and maybe it’ll do a little damage every cycle to the output drivers…
Response:
>You will have to allow for the startup current which is 6 times running >load. Your going to end up with a bank of batteries to store and take care >of. >Would it not be easier to just start the gen up 2-3 times an hour and if the >refer needs to cool it will if not it wont.
Or go full circle to a large smart UPS that’ll start the generator when the batteries get down to (say) 50% and shut it down when they get back up to (say) 90%, and will run the rest of your important appliances as well. Sizing the battery bank is left as an exercise for the student. Hint: You don’t need, and should not use, a spreadsheet.
Response:
> WOW your looking at a HUGE UPS. > You will have to allow for the startup current which is 6 times running > load. Your going to end up with a bank of batteries to store and take care > of. > Would it not be easier to just start the gen up 2-3 times an hour and if the > refer needs to cool it will if not it wont.
It is difficult to start the gen 3 times per hour when I am at work or sleeping. I do not want to be a slave to the fridge. Someone would steal the gen if left unattended(outside).I believe that except for the surge(larger inverter) that this is doable,If I recharge the battery every evening(for 1 or 2 weeks).I may install a timer relay that might limit the run time to every few hours or when a temp sensor(in the fridge) deems it needed to run to prevent food spoilage. Bead_runner
Response:
>I do not want to be a slave to the fridge.
Exactly. Your idea of using an inverter and battery in concert with a once-a-day generator run is sound. Here are some deals on inverter/charger combos. (See the archives for comments on this dealer) https://www.sunelec.com/Distributors_/Trace/heartreftrace.html Looks like you could have a suitably sized reman. Trace DR for $700, or $500 for a Heart. One comment – these units usually have a three stage charging routine that tapers down. So be sure that the charging time is compatible with the planned generator run time for your other uses. Wayne
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