Has anyone adapted an UPS (uninteruptable power supply) unit as a sine wave inverter?
Last year I bought an inexpensive ($149) modified sine wave inverter (2KW run/4KW surge) from Harbor Freight Tools to run the microwave, coffee pot, and any other short term use appliances without having to fire up the generator when dry camping. Problem is that the microwave in particular does not like modified sine wave power - it makes more noise than heat in the food.
High power sine wave inverters are pricey ($1,000 and up). 3000KVA UPS units are available on Ebay for well under $200. Their output is an extremely clean (computer compatible) sine wave. Problem is that they're meant to be used for short term outages as "plug-in-the-wall" devices.
RVDude said
04:42 PM Sep 3, 2006
Have you tried a different brand/model inverter?
Warning: some science content follows - particularly the P.S.
Do not think that a UPS delivers true-sine wave output either. A UPS is nothing more than a battery and an inverter. It isn't easy to make a pure sine waveform from flat-line DC and is the reason why pure-sine intervers are so dang $$$$. One is also not going to get pure-sine from a low price consmer UPS - note shipping that eBay UPS is going to be big bucks. "Computer grade" does not mean (particularly from the *consumer* product perspective) pure sine either.
Pure sine output is NOT always required to run sensitive electronics. Inverters differ greatly in the "squareness" or "chopped-ness" and the overall "quality" of their output and hence differ greatly in their impact on sensitive electronics. In addition do not think that even a genset delivers pure sine ouptput either - be it a traditional commutator genset or the newer more efficient inverter genset technology. My Onan 5k messes greatly with my microwave (the only problem among my piles of electronic gadgets) but my 1200w Xantrex inverter (Costco for $70) runs the micro flawlessly.
It's all about being lucky that the output of your inverter is "compatible enough" in both wave form (how sinusoidal), frequency (the 60hz stuff), and overall output quality with your electronics. Which, in general is no problem most of the time.
Hence, it is important to distinguish between clean power (noise/spikes/surges/highs/lows/sags - the output of a UPS) versus output quality versus the myriad of modified sine wave inverter outputs.
Bottom line: I would try a different brand inverter and you'll probably see your problem go away.
PS - To make 120volt AC (Alternating Current the stuff household appliances run on) from 12volt DC (Direct Current - the stuff your vehicle/RV runs on from batteries) you essentially use some fancy circuits (transformers) to amplify (step up) 12v into 120v while at the same time take that DC and essentially flip a switch which reverses the +/- ploarity some 60 times per second to make that DC into the "alternating" 60hertz or 60cycle AC. The on-line encyclopedia www.wikipedia.com has a nice description.
Good luck!
Jack Mayer said
06:31 PM Sep 4, 2006
I agree with RvDude. Try a different inverter - preferably not a really cheap one. The under $100 inverters rated at 2000 watts are generally very poor.
Tom & Paula said
11:14 AM Sep 27, 2006
I am considering getting a Laptop GPS system. Would anyone know what Wattage inverter I would need to run the laptop while traveling. Thanks for any advice
Tom
RVDude said
10:50 AM Oct 3, 2006
If all you are going to do is run your laptop or a cell charger, I'd suggest using a 12v power supply designed to do just that instead. Targus www.targus.com and iGO www.igo.com (my preference as it is avail at Radio Shack in many models) are designed for laptops and have a myriad of plug adapters at $10ea. for most any other sensitive electronic devices making this a truly "generic" adapter which will last for life and any number of devices.
Otherwise look at the label on the back of your 110v laptop power supply and read the *input* wattage. Should say something about *input* amps (A) or watts (W). If only amps multiply by 110 to get watts (amps X volts = watts). This will be the *minimum* wattage for your inverter. For a laptop this should be in the range of maybe 70-150w (or about 1 amp at 110v which by the equation above is about 10 amp at 12v).
Also be aware most "cigarette lighter" plugs can only handle 5-10 amps at 12v (which equates to 60-120 watts regardless of voltage).
BTW - The laptop GPS unit is powered by the laptop USB port and you need not worry about it separately.
Has anyone adapted an UPS (uninteruptable power supply) unit as a sine wave inverter?
Last year I bought an inexpensive ($149) modified sine wave inverter (2KW run/4KW surge) from Harbor Freight Tools to run the microwave, coffee pot, and any other short term use appliances without having to fire up the generator when dry camping. Problem is that the microwave in particular does not like modified sine wave power - it makes more noise than heat in the food.
High power sine wave inverters are pricey ($1,000 and up). 3000KVA UPS units are available on Ebay for well under $200. Their output is an extremely clean (computer compatible) sine wave. Problem is that they're meant to be used for short term outages as "plug-in-the-wall" devices.
Have you tried a different brand/model inverter?
Warning: some science content follows - particularly the P.S.
Do not think that a UPS delivers true-sine wave output either. A UPS is nothing more than a battery and an inverter. It isn't easy to make a pure sine waveform from flat-line DC and is the reason why pure-sine intervers are so dang $$$$. One is also not going to get pure-sine from a low price consmer UPS - note shipping that eBay UPS is going to be big bucks. "Computer grade" does not mean (particularly from the *consumer* product perspective) pure sine either.
Pure sine output is NOT always required to run sensitive electronics. Inverters differ greatly in the "squareness" or "chopped-ness" and the overall "quality" of their output and hence differ greatly in their impact on sensitive electronics. In addition do not think that even a genset delivers pure sine ouptput either - be it a traditional commutator genset or the newer more efficient inverter genset technology. My Onan 5k messes greatly with my microwave (the only problem among my piles of electronic gadgets) but my 1200w Xantrex inverter (Costco for $70) runs the micro flawlessly.
It's all about being lucky that the output of your inverter is "compatible enough" in both wave form (how sinusoidal), frequency (the 60hz stuff), and overall output quality with your electronics. Which, in general is no problem most of the time.
Hence, it is important to distinguish between clean power (noise/spikes/surges/highs/lows/sags - the output of a UPS) versus output quality versus the myriad of modified sine wave inverter outputs.
Bottom line: I would try a different brand inverter and you'll probably see your problem go away.
PS - To make 120volt AC (Alternating Current the stuff household appliances run on) from 12volt DC (Direct Current - the stuff your vehicle/RV runs on from batteries) you essentially use some fancy circuits (transformers) to amplify (step up) 12v into 120v while at the same time take that DC and essentially flip a switch which reverses the +/- ploarity some 60 times per second to make that DC into the "alternating" 60hertz or 60cycle AC. The on-line encyclopedia www.wikipedia.com has a nice description.
Good luck!
I am considering getting a Laptop GPS system. Would anyone know what Wattage inverter I would need to run the laptop while traveling. Thanks for any advice
Tom
If all you are going to do is run your laptop or a cell charger, I'd suggest using a 12v power supply designed to do just that instead. Targus www.targus.com and iGO www.igo.com (my preference as it is avail at Radio Shack in many models) are designed for laptops and have a myriad of plug adapters at $10ea. for most any other sensitive electronic devices making this a truly "generic" adapter which will last for life and any number of devices.
Otherwise look at the label on the back of your 110v laptop power supply and read the *input* wattage. Should say something about *input* amps (A) or watts (W). If only amps multiply by 110 to get watts (amps X volts = watts). This will be the *minimum* wattage for your inverter. For a laptop this should be in the range of maybe 70-150w (or about 1 amp at 110v which by the equation above is about 10 amp at 12v).
Also be aware most "cigarette lighter" plugs can only handle 5-10 amps at 12v (which equates to 60-120 watts regardless of voltage).
BTW - The laptop GPS unit is powered by the laptop USB port and you need not worry about it separately.
-- Edited by RVDude at 12:52, 2006-10-03