What would be a good pure sinewave 12V to 120V inverter? - Page 1
Forum section: electronics / projects

author: sourcecharge
author_rank: Regular Contributor
timestamp: July 24, 2018, 02:04:37 am
content: Anyone know of a good inexpensive pure sinewave inverter?

author: grythumn
author_rank: Contributor
timestamp: July 24, 2018, 06:29:23 pm
content: What load?

author: rx8pilot
author_rank: Super Contributor
timestamp: July 24, 2018, 06:46:17 pm
content: Define 'GOOD'Good price?Good size?Good Efficiency?Good reliability?Good sine accuracy?Good surge handling?Good features - battery charging, remote control, etc?

author: sourcecharge
author_rank: Regular Contributor
timestamp: July 24, 2018, 07:17:22 pm
content: Quote from: grythumn on July 24, 2018, 06:29:23 pmI'm looking for one that will power my FG and a linear power supply. I'm guessing about 300W, but I was think about getting one with some extra power.800W to 1KW?Quote from: rx8pilot on July 24, 2018, 06:46:17 pmGood price, efficiency, reliability, sine accuracy...I think is probably all I'm asking for..Size, surge, and features are not important.

author: rx8pilot
author_rank: Super Contributor
timestamp: July 24, 2018, 07:33:29 pm
content: Quote from: sourcecharge on July 24, 2018, 07:17:22 pmIn that order?If the price is the top concern - the other three will have to suffer.I have had great experiences with Xantrex ProSine boxes - running for years in rather difficult situations.https://xantrex.factoryoutletstore.com/cat/83092/PROsine.html?cid=295303&chid=1&campaignid=1016420814&adgroupid=49587243083&creative=248575297889&targetid=kwd-297656589015&matchtype=e&device=c&network=g&gclid=Cj0KCQjwnNvaBRCmARIsAOfZq-1inPgfr8ntHaCMz4Xvcmq5bfzPSd1YFHtt09KgizifTopRxp7Pl7IaAjeLEALw_wcBThis is also a good option and a good store:https://theinverterstore.com/product/1000-watt-inverter-charger/The cheaper and more random boxes are (in my experience) a fingers crossed adventure. Some are passable, some suck, some are dangerous. It is hard to know until you get it and use it.So....how important is price?PS: on the 12v side you need really nice cables with nice terminations and as short as you can possibly make them. The IR drop with high current 12vdc is a battle that can only be won with a lot of copper.

author: Bratster
author_rank: Frequent Contributor
timestamp: July 24, 2018, 08:01:20 pm
content: I will add a second vote for either of the links that rx8pilot posted.I have some of those older Xantrex Pro sine units and they are very nice. I have also used some different models of the low-frequency aims inverters and they are nice as well.I would definitely want one that has that GFCI outlet on the output. As that generally means the neutral is bonded to ground so it will be just like a wall outlet.Sent from my Fi Moto x4 using Tapatalk

author: BrianHG
author_rank: Super Contributor
timestamp: July 24, 2018, 08:04:28 pm
content: If 900watts is acceptable, Xantrex has a bargain 285$ unit here, 195$ for 540 watts:https://xantrex.factoryoutletstore.com/cat/83094/Xantrex-PROwatt-SW.html

author: sourcecharge
author_rank: Regular Contributor
timestamp: July 24, 2018, 08:31:36 pm
content: Ouch, I was thinking maybe 80 bucks, not 500...I might be expecting too much...

author: Bratster
author_rank: Frequent Contributor
timestamp: July 24, 2018, 08:59:00 pm
content: Quote from: sourcecharge on July 24, 2018, 08:31:36 pmFor something that's quality, yes.I think the lowest you can go and still keep a quality inverter is $200 and up depending on wattage. Maybe $150 for a small wattage one if you find a good deal.keep in mind how expensive the equipment you're plugging into it is.If all you're plugging into it is inexpensive consumer goods and you will be always near to this inverter when you are using it. You may be able to get away just fine with a cheap one.But if you're going to be plugging more expensive equipment into it. Or you plan on leaving this running unattended for a bit. You probably don't want the cheapest thing out there.Sent from my Fi Moto x4 using Tapatalk

author: NiHaoMike
author_rank: Super Contributor
timestamp: July 24, 2018, 09:04:39 pm
content: What about hack a used UPS?

author: sourcecharge
author_rank: Regular Contributor
timestamp: July 24, 2018, 09:08:17 pm
content: there's a AIMS Power 300 Watt for like 75 bucks and 600W for 130 bucks at wallywart.They're both pure sine output.Have you guys heard anything about AIMS?Quote from: NiHaoMike on July 24, 2018, 09:04:39 pmHow would I do that to run off a car battery?

author: sourcecharge
author_rank: Regular Contributor
timestamp: July 24, 2018, 09:18:59 pm
content: I think the ups is still connected to mains power isn't it?So when you say hack, you meant literally find the battery and switch the input supply from the internal battery to an external battery?Sounds do-able, but a pain in the but.

author: rx8pilot
author_rank: Super Contributor
timestamp: July 24, 2018, 09:33:30 pm
content: For $80 - your expectations should be exceedingly low.For me - the quality of the inverter should be matched to the expected loads. If I am going to run a computer, TV, etc - I will use a nice, well-respected brand with a clean, stable output. What do you plan to attach to it? Something you care about?

author: sourcecharge
author_rank: Regular Contributor
timestamp: July 25, 2018, 01:36:17 am
content: so, I think I'm going to go with the AIMS 600W pure sine for $130, here's the manual below.Thank you all for the input.I do have one last question though.The point of buying this was to isolate a ground loop between 1 FG / a 120VAC, DC PS and a separate 120VAC, DC PS.I have this 50V 50A PS that runs off of the 220VAC.If I run the FG/PS off of the inverter that is running off of the DC PS that uses the 220VAC, does anyone think that this will isolate the ground between the FG/PS and the 2nd PS if of course I use opticouplers to interface the two.Not too hopeful of it, but I thought I'd try it to see if it works so I can save on the battery.Thanks again.(Edit: Each 120VAC PS has 3 outputs that I'm +/- biasing, that's why I'm not taking it directly off of the 220VAC DC PS)

author: IDEngineer
author_rank: Super Contributor
timestamp: July 25, 2018, 02:47:55 pm
content: If by "pure sinewave" you mean "as close to mains power as possible", how about driving the generator from an inexpensive genset with a 12VDC motor? Here's a ~700W genset that can be had for ~$90 when it goes on sale (which is VERY often):https://www.harborfreight.com/900-max-starting700-running-watts-2-hp-63cc-2-cycle-gas-generator-epacarb-63025.htmlRemove it from the gas engine and drive it with a ~1HP 12VDC motor rated for the same RPM. Voila... 12VDC to 120VAC single phase and you can scale the motor size to whatever current you wish to pull out of the generator, up to its own current limit of about ~5 amps. You could probably find a suitable used 12VDC motor for free/cheap with a bit of looking on Craigslist, etc.Just a different way of looking at the problem.

author: MarkL
author_rank: Unknown
timestamp: July 25, 2018, 06:54:53 pm
content: Small gas-powered generators of the non-inverter type hardly have clean sine wave outputs. I have 3.5kW Generac model and it's pretty ugly open or under load (although nothing so far has refused to run on it).Here's someone with some scope captures of their generator (near the end):http://www.jkovach.net/projects/powerquality/Also, if you want 60Hz output from such a generator, you need to turn the shaft at exactly 3600 RPM, 60 revolutions per second = 60Hz. You might have trouble finding a 12V motor to do that under varying loads.sourcecharge: Is the goal to float the ground on your FG and the one PS? Perhaps a diagram of what you're trying to accomplish would help, unless you've already settled on a solution.

author: james_s
author_rank: Super Contributor
timestamp: July 25, 2018, 07:30:29 pm
content: 80 bucks is ridiculously cheap for a pure sine inverter. In that price range you're looking at the standard "modified sine" and it's still likely going to be rather low end. There are a few pure sine inverters for under $200 that may be ok, but not very many, that's very low end pricing territory.

author: sourcecharge
author_rank: Regular Contributor
timestamp: July 25, 2018, 09:31:25 pm
content: Quote from: MarkL on July 25, 2018, 06:54:53 pmThe goal is to separate the digital logic from the power side due to a ground loop.The solution is simple, because this is not a production unit, and used only for research, I can limit the variables by simply disconnecting the grounds between the digital and power by using separate PS that are not on the same ground.The thing I was wondering was, if 240 lines are referenced to but not connected with mains ground, does that mean they are isolated between something else that is running a 120 line. I would think that because the 240V line uses one leg of the 120V line, that they would not be isolated, but IDK.I'm just trying to be cheap and save the battery cost.Thanks for asking though..

author: james_s
author_rank: Super Contributor
timestamp: July 26, 2018, 04:01:24 am
content: If you just want to break a ground loop, why don't you just use an isolated DC-DC converter between the power supply and the equipment?

author: sourcecharge
author_rank: Regular Contributor
timestamp: July 26, 2018, 10:22:27 pm
content: Quote from: james_s on July 26, 2018, 04:01:24 amDo you mean a battery powered regulator(s)?I would still have to opticouple the FG to the isolated logic.I think I have an opticoupler that could do that with the FG.I was planing to do just that, but it would require more ICs and components on a board that's already way too populated.Also, I might want to isolate the Power PS instead of the logic side.The inverter allows me to do it either way.

author: NiHaoMike
author_rank: Super Contributor
timestamp: July 27, 2018, 12:16:08 am
content: An isolation transformer will let you use ground defeating adapters more safely.