Why is My Inverter Only 80 Volts?? - Multimeters and Inverters - Pure Sine vs MSW

Note: I use my own terminology in this video and this likely isn't technically what 'phase correction' means in inverter spec sheets. However inverter products which advertize this feature seem to also have the 'better' method of making modified sine outputs. As far as I know this is something you will need to verify yourself - something you can do by comparing the readings of an RMS DMM to that of a non RMS DMM under both high and low battery voltage.

[@ThingsWhichArentWork]

A great explanation of the different techniques used for modified sine inverters. I learned something new and that's always good. Thanks knurlgnar.

[@jlaughlin1973]

Thankfully I found this video and saved me tons of time rechecking all my wiring. My voltmeter was exactly the problem, reading only 87 volts. Thank you!!

[@TheMexicaNigga]

Also look foward to watching your vids. Very informative and the way you break it down is A+!

[@tbbw]

Yeah i feel the same :)

[@dennismcatee1313]

Glad I found this video. I thought my cheap harbor freight 1000watt inverter was bad, now I know why I was not getting the correct reading on it. Thanks.

[@DoNE021]

I got a 12v/220v Inverter i thought it was damage until now. It only show's 175v on my Fluke 600$ multimeter, But works when connect stuff to it. Thanks for the video. :) I'v search about it on the internet, but didn't find anything except your video.

[@TheOldmankk]

Agreed, a good DMM is a must. I am happy to have my Brymen 257. Btw, very good explanation, thumbs up Pal.

[@austin30233]

Thanks for the info. Informative as always.

[@martinjaramillo2429]

Cool video, thanks for the new perspective.

[@gragra556]

Thank You! Very good info. Was wondering why my inverter only reads 91 volts. Also used same free Harbor Freight voltmeter.

[@paulsingh9043]

Glad you made this vid !, I learnt something today !👍🏾

[@brucebear1]

Thanks for your knowledgeable and helpful videos. I have (and use) a Kill-a-Watt meter a lot. Do they work like an RMS meter? Thanks!

[@markpowell4701]

I am looking forward to your Multimeter video. Thanks in advance.

[@markpowell4701]

Thanks for the very informative video, I would have assumed it was the Inverter, now I know it could be the Volt meter. I hope you have more info soon, as it has been a long time between video's.

[@nodriveknowitall702]

Cool vid. I was playing with a couple inverters I have laying around last night. I fried a cheap one that was already partially broken while seeing what the waveform does under a heavy load. I've got a couple multimeters and a bench oscilloscope, but it sure would be nice to have a multimeter that shows waveforms. I've been considering getting a used fluke scopemeter, but I'd like to have something I can easily carry around that doesn't necessarily have to have as many bells and whistles, but preferably with industrial safety ratings. Am I asking too much? Anything you'd recommend?

[@ghengiscrayon]

Thanks for this video! As always. Still love to help you with your work.

[@danyala.1659]

Long time no see man! Hows it been? I see you have really cut down on the videos. What new projects have you been working on? I want to try to run a uninterrupted power supply on bank of crystal power cells using a joule ringer circuit. But, I see that there will be a major obstacle of not enough amps. But, I'd say its worth a try. I hope to hear back from you and see more videos! I would also like to possibly see a video with a small motor spining a generator to run in a loop. Obviously, you will have less output then input in that scenario because of all of the losses. But, it would still put a end to alot of "rumours" and confusion. You would also get alot of feedback.

[@sofabike]

I watched all 12videos on power-inverter review. My Project; to power 220volts 2-splite phase aluminum welder from my work-truck (12volt DC battery). Most common welder settings on a welding-arc is 22volts and 20 to 30amps. So, welder takes 22v x 30a = 660watts. I already tray to power welder with two 120volts 2000wats inverters, connected in series by neutral wires. On a 2 hot wires ends I've got voltage constantly waiving from 190v to 240v. Welder started, but after attempt to fire arc (on minimum weld current 20a) inventers got power off. It was modify-sine way inverters. I returned them to a shop. Ordered a new 12v 2 split-phase 220volts 5000 watts inverter. Will report you as soon as I get new inventer

[@knurlgnar24]

Be sure you have enough battery power and very thick cabling for that inverter. You're looking at needing multiple batteries in parallel to adequately power it. If you do it should work!

[@sofabike]

***** 1; instead of very thick cables I am planning to use 2 or 3 cable running in parallel. Let say I will run 3 cables 4gages thick in parallel so 4 : 3 = 1.33gages 2; yes planning to use 2 batteries and +alternator 220amps

[@DMAN22yeah]

+sofabike dual 4 gauge is 1gauge

[@GereDJ2]

Nice video. I was experiencing the same thing you are in a different way. I put a Solar ice making system together using a small 120v Dometic counter top ice maker which draws about 100 watts, but needs a kick-start of about 800 watts or so to kick the compressor for about a half-second. I can't get the system to work. I'm using a 200 watt solar panel, 20 amp capacity charge controller, 2-12v deep cycle batteries, a Harbor Freight modified sine-wave DC/AC Inverter w/750 watt continuous -1500 watt surge, powering the Dometic ice maker. The ice maker turns on and runs for about 50 seconds, then the inverter shuts off into the over-load signal In checking the output of the inverter with a Red Harbor Freight volt meter just like yours, the output is about 102 to103 volts with the voltage rapidly and continuously fluctuating between 60 to 100 volts even when not powering anything. The batteries are fully charged to 12.7v. It will run a drill or blender or 100 watt light bulb, but not the ice maker. To check my volt meter, I measured my house AC voltage and it holds a steady 120 volts. Any ideas what's wrong?

[@brucewayne-cave]

Great Explanation...

[@hopster81]

Thank you VERY much, had exactly this problem with my inverter/meter

[@knurlgnar24]

Glad to hear this older video is still helping people. Thanks for the comment!

[@TheOffgridkid]

Good information!

[@jbell2018]

Your videos are awesome and i learn so much. But could you consider upgrading to a 1080p camera.

[@FloydThomasIII]

Can you tell me the make and model of the RMS meter that you use? I have thrown away, taken out of service, several power inverters because I thought that they were dying. Would like to get the correct meter to test from here on out.

[@FreiGuy329]

Your should be a teacher. I learn things when I watch your channel. The SUN PRO heater was an eye opener for sure. Thanks

[@knurlgnar24]

Thanks!

[@JustAnOldMan]

is your phase corrected models the same as modified sine wave inverters?

[@Wiresgalore]

I'm curious what is going on with the Schumacher inverter under low-voltage conditions at about 8:00, sudden current draw of over 2.5A? D: what could possibly be dissipating 20-30W in this instance?

[@knurlgnar24]

That's a good question. It is common for inverters to draw quiescent input power that varies significantly with input voltage and there could be a lot of reasons for it. I have to admit that I don't know why this particular one has this behavior - though I do believe I remember the internal fans turning on at low input voltages for some reason...

[@williamstaten8102]

Always see you find inverters that has a live neutral. So it got me testing all of mine. Tested Schumacher 750 like the one you had the HD in, Centech 2000w and the OSP tiger claw 1500 sine wave and none of them was live neutral. One thing I wonder is what you don't like about the Centech 2000w you had in your box opening video on the OSP 1500. All three of mine work really well and don't have a live neutral. I have had some really shit inverters in the past and gave them away. Funny all the ones I keep have the polarity correct output.

[@neikesd]

dude you love those inverters why did my 5000 watt blow when i pluged it in to my compressor granted it was to much load but the mosfets and the caps blew big time...... but not the fuses or shut down protection had a large battery bank charged?

[@hafizrazi85]

Nice video, i want ask the brand Solartronics power inverter 2000/4000 watt, this it ok or not.... Did you have it...??

[@craiglatour8680]

I tried using a 2000 watt harbor freight inverter to run my oil fired furnace. It wouldn't run it, I checked the voltage it was showing 90 volts. I now know why. Thanks. I think I'm going to look into pure sine wave

[@aboyad]

Hello sir, from your experience what is the ultimate pure sine wave power inverter in term of watts, quality. im looking for 3kw 240v. Thank you

[@523panda]

Can you do a review on Sunforce 1000- Watt Pure Sine Wave Inverter and give us your thoughtas as usual? Thanks.

[@lt7656]

Great Videos ! I have just picked up a APC smart UPS 2000 RT with a 4 battery (48volt) pack that needs to be replaced, If I use 4-12v deep cell marine batterys instead of the original 12v 9ah batterys will this UPS still keep batterys charged or is it too much for the built in charger?

[@DMAN22yeah]

it would charge slowly, but a ups is only meant to run for as long as the cheap batteries will last without overheating. you will need to improve the thermal capabilities.

[@MilesPrower1992]

On my little Harbor Freight modified sine, the meter said 105, the Kill A Watt said 117. I also had an old UPS I tested. Kill A Watt said 114, and the meter said, lo and behold, 80

[@jamesrussellnix3]

You know a lot more than I do so I thought id ask, I have a board that burnt and copper plate is exposed, could I bypass with a blank board or is there a better way? Would be happy to send pics. Power bright 2300 110v. Cap and fets blew- not an engineer but you've inspired me to try.

[@jamesrussellnix3]

To rephrase, I know it's possible to recreate but I'm having a hard time determining how many layers pcb. I was thinking of coating with epoxy to insulate. Any thoughts or suggestions to a newbie amateur?

[@GoingOffGrid101]

is a kill a watt P3 meter a true rms meter ? man i have been craving another video from you, could you review a Xantrax sw 3000? or a new Eliminator 3000W inverter (the plastic one) and do you happen to have a nice low watt pure sine wave inverter you wanna sell? im looking for one.

[@lanceguilin]

fliping720 Kill a watt is NOT true rms. It's interesting that knurlgnar24 just did a video on this topic. I just discovered today that the Kill a watt is NOT true rms. I read 84 volts today when I overloaded my inverter. But my inverters are pure sine wave. ***** , does this only apply to modified sine wave inverters? or does it equally apply to pure sine wave inverters?

[@GoingOffGrid101]

lanceguilin thanks, i didn't think so seeing i was getting 140 volts :D

[@Wiresgalore]

lanceguilin Thats strange seeing as how Knurlgnar's Kill-A-Watt consistently reads correct in all his videos and its also stated in the manual that the unit is indeed true RMS. Possibly a knock-off?

[@Eman2000]

yes it is true RMS according to the manufacture look at page 11 on this manual all specs are listed as true RMS www.p3international.com/manuals/p4460_manual.pdf

[@knurlgnar24]

lanceguilin Pure sine inverters are not pure sine under all input and output conditions and the waveforms can become severely distorted at times, especially with lesser quality 'pure sine' inverters. A true RMS DMM should be used for both. You can 'get by' with the standard multimeter in most cases though if accuracy isn't important for your particular measurement.

[@mpotkovac]

Good video

[@greensunnergy5737]

Hi, could you tell me the ítem number and brand name of the oscilloscope you are using? Thanks

[@JoshKilen]

what multimeter do you normally use?

[@bhsolar100]

Hi knurlgnar . I was wondering why the post on my batteries get fairly hot when I draw about 800 watts from them? My batteries are two big 6 volt golf cart batteries, wired in series with a 2 gauge wire to get 12 volts. Any suggestions? Thanks.

[@DMAN22yeah]

bad connection to cable

[@robertschilling3308]

Could you please reveiw this inverter and comment? It seems impressive. I saw it on amazon. Thanks. Magnum Energy MS4024PAE 24V Pure Sine Wave Inverter 240VACL

[@georgegoff8298]

I am building a emergency solar generator for when we have black outs. Sofar I have 4 100w panels, 4 120 anp 12 volt AGM batteries, I am going to order a 3000w pure sign wave inverter. As fas as the charger controller go's, I don't know which type to go with, an MPPT or a PWM, which do you think would be best for this application? Thanks,

[@albertsparrow9485]

Get a mppt is phases into pwm on float charge.

[@edmoe122]

do you repair mppt controllers for people ?

[@raym9691]

What type of meter is that you are using?

[@kainduran3480]

Great great info learning a lot from your videos but I'm having a problem hoping you could help inverter the low voltage comes.on.but I checked the batteries they're fine the low-voltage is 50v it it should be at 42 volts the the fans keep on turning on Non-Stop but at night when it's a bit cooler the the fans turn off. Like there is a thermostat in it. When is sunny and voltage is 55 volts the inverter lights work fine it is a cotek sp2000 48v. What do you think?

[@knurlgnar24]

What a coincidence! I just received delivery of a Cotek SP2000 48V inverter yesterday! (I have had a 4000W version for years) I can say that the 4k model works perfectly with regard to the undervoltage lockout and is a pretty decent inverter - though it falls short of their earlier SK series so if you can find that one get it... The fans seem to always run noisily even at light loads for me and that's just how it is designed I believe to reduce temp cycling which is bad for electronics. If you measure directly at the inverter terminals while the inverter is under load do you get 50v? Also, DMMs frequently vary by a volt or two (at 50V) from meter to meter despite their advertised accuracy numbers. Have you compared it with a variety of other DMMs?

[@kainduran3480]

@@knurlgnar24 okay today I followed your advice I took it off from where is and connected it with healthy 4 batteries to make 48 volt the voltage is 52.2. I turn on the inverter. And the inverter goes in to low voltage. I wiggled wires around and the same no response that's the far as my mind can go for electronics.So would you consider repairing my inverter?? of course I would have to pay you that's not a problem but I don't know how busy you are you. Let me know so I can ship it out ASAP. When I was ordering this inverter the original order was for a a different model but obvious I really needed it it was late already so they offered me this inverter. PS nothing beats the 3000 watt samplex inverter I don't know about cotek anymore....

[@leonmccalla]

"phase correction" is probably a translation from a Chinese term but we get what you mean. is that a craftsman scopemeter you use? what model is it?

[@knurlgnar24]

82289. Long ago obsolete but it works well.

[@rgstever]

I've used true rms meters from fluke and the cheap inverters really do put out less than 110v, even my tektronix 2445 scope shows this. It has everything to do with poor QC.

[@TammyDenseDdank5658]

Well, if the inverter does not put out a correct sinewave for which the appliances are optimized for, then it sort of a doesn't work right indeed and could damage devices. These modified inverters are more like toys of some sort. There should be a mandatory huge warning label on it.

[@DMAN22yeah]

they work fine for most loads

[@williamklein6749]

Just found your vids. Really like them. When the Zombie Apocalypse how can I make sure you are on my team?

[@TheCumminsturbo2]

Take a look at Napa’s Xtrax 1500 inverter very interesting design thought it looked iffy at first but will do 1540 continuous with the input fan running continuously but can barely be heard and the output mosfet fan cycles I could send you some pics but not sure how to I ran 1400 watts four 2hours with no problem

[@trumax10]

I have a dewalt 1000w and on 2 rms meters klein cl800 and fluke 115 read 155.4 volts the only meter I have thats not rms is a cheap scope reads 166.7 allsun em125..... could you recommend an inverter thats perfect (or close enough) to run 2 battery chargers and a 385 watt soldering iron? ... im asking for a friend😐

[@knurlgnar24]

Those aren't terribly demanding applications and it sounds like your inverter has failed in a rather damaging/dangerous way. I think you could purchase most any 1000W to 1500W pure sine inverter and it would work for that application.

[@AftermarketCRX]

I have a cheap Harbor Freight 1200 watt inverter that reads under 100 volts with my meter as well. I found that a Kill-A-Watt meter will show the correct voltage. For those of us who can't afford those expensive multimeters.

[@tbbw]

There are a few not so expensive multimeters that are true rms... you just need to keep an eye out :)

[@rogerdelaney3320]

Thank you. I thought that my brand new inverter was junk. At 12.6v on the battery the multimeter I have reads 92.3v.

[@rondamon8004]

Can you put a link of that wave form meter...very useful to have it, and very informative video..thanks...!!!

[@knurlgnar24]

It is long ago obsolete and difficult to find used anymore. While I still like this one there are other similar scope meters for sale now though that are much more capable.

[@vrichmarketingrenewableene9418]

Good day sir..very educational videos you have there..a, im thinking if this is possible..to use a 1000 watt pure sine wave inverter then hook an extension cord on the output and hook up a 500 watt grid tie inverter on the extension cord to produce 1500 watts of output on the remaining slots on the extension cord..?

[@DMAN22yeah]

thats not how it worjs

[@mekuranda]

@@DMAN22yeah Why not?.....I do that all the time...works a treat

[@joe40867]

When is your next video?!?!

[@TechnoEveryday]

I believe you're country of residence uses 110VAC and the cheap meters are showing 82V In 220V countries, it should be around 175V, right?

[@knurlgnar24]

It depends a lot on the meter and inverter but that would be a reasonable voltage reading to expect. What I think is important to know is that a non-RMS meter isn't useful to measure output voltage on a modified sine inverter. It will tell you whether there is any output, but not the voltage accuracy.

[@TechnoEveryday]

Fully agree with you but perhaps you didn't understand my point about 220v output vs 110v inverters

[@galleno64]

What model Fluke meter are you using to graph the sine wave?

[@DMAN22yeah]

its a discontinued craftsman

[@mustknowfacts6965]

Same problem with my inverter. How i resolve ?

[@ElektrikaCo]

It all comes down to this 'you get what you pay for', whether its a multimeter, inverter or what not...

[@Belalsyr]

what about analog multimeters?

[@ppger44]

Do RMS Meters specify that they are RMS?

[@knurlgnar24]

Yes. Always. If they don't in the specs then you can be assured that they are not an RMS meter.

[@billynelson8975]

awesome,same exact meter,same exact results el cheapo volt meter lied-saved time!

[@user-ew3qj5sn2p]

If you have a power supply that's DC 14.5 bulbs, and you have an inverter. That's supposed to put out a 110 to a 125 bolts. Why is it that the voltage is reading only a sea voltage on a multimeter? You should be reading a 115 to a 125 V, which does not especially when you have constant current, why is that??

[@edwardnundahl4886]

With electronics dc current to ac current back to dc current. Loads of work is the performance im looking for.

[@brianc5592]

Good vid. I just bought one of the cheapo meters because I'm poor and I didn't know any better. And also because I don't mess with this stuff a lot and just couldn't justify the expense of anything better. Is there a decent meter that's more affordable for the casual DIYer? I see a lot of inexpensive meters on Amazon. The positive reviews are very positive but most of them have their fair share of negative reviews and the negative reviews are extremely negative. It's tough to know who to believe. Are cheap meters actually dangerous or is the worst thing that's likely to happen is the meter will just die and you'll lose whatever you paid for it? I'm guessing anything can die early. Anyway, the meter I have looks a lot like the super cheap Harbor Freight one you showed but it has a different brand name. It was only 20 bucks and I figured I'd tinker with it and maybe learn something.

[@knurlgnar24]

Cheap meters have their place and are good enough for many people. If you're doing more than just checking for the presence of voltage and the like I would spend the extra money for a true RMS meter though. I wouldn't hesitate to purchase and use an inexpensive meter. Anything can break so you need to be careful (for safety sake) with all brands. For example you can get an Extech true RMS autoranging DMM for around $20 if all you need/want is something basic. They're made cheaply but they do work.

[@brianc5592]

***** OK. Thanks. Looking at it now. The one I have doesn't have an actual brand on it but does have the number DT830. I see these around online under different brand names. Some people say they're fine and others say they fried the first time they tried to test AC with them. I checked a couple of inverters, some batteries and a couple of wall outlets with this. It didn't fry and seemed to be more or less accurate. The only PSW inverter I have read at just about exactly 120. I have a 750 watt MSW Diehard inverter but haven't tested it yet (it looks exactly like those Schumacher 750s you had in one of your videos with the sloped plastic case). Works OK for some things. Anyway, love your channel. I'll watch pretty much anything you put up that has to do with electrical/electronics and assorted tinkering. It's all appreciated. Your personality is fun too. The personality will always make or break a KZbin channel. I think you can probably be as big or small as you want to be.

[@kevin9c1]

Nevermind that, why does the inverter spike to 2.5A under 13 volts?? There is no output load!

[@DMAN22yeah]

some component inside

[@danielhorne6042]

i got that green meter

[@danielhorne6042]

and mine reads 240 on my modified sine wave inverter ?

[@-GrimEngineer-1337]

It's 80 V because you are using a crappy modified sine inverter instead of a true sine, and your meter is cheap and it sucks because it is average responding instead of True RMS. Nuff' said.

[@bruce29775]

without using a meter initially I knew something was wrong. My electric hair clipper didn't work. 3 different meters showed 80-83 volts. I just wanted to know why. Wasted 18 minutes and learned nothing