I ticked off a sponsor 

I am a developer for frequency inverters and I fully agree that this behavior is normal. The reason is that with that massive overload, the output inductance saturates - this could already lead to oscillation. Additionally, controlling a saturated inductance and a dropping battery voltage is extremely difficult. To prevent an overload in this case, the physical size and cost of the inverter would probably be increased by factors (assuming this device is already at a good quantity). So there are only two possible reactions that a device with that size on this load can do: Either shut off or accept some oscillations. On the other hand: the input circuit with the capacitive voltage dividing on the power meter is a very bad design practice, although this is done a lot especially in cheap products. When testet according to standards that are mandatory for sale in the EU, most of these products fail. All products must withstand some harmonics/flicker/emi/...

This is a revised version of the video. The original version inadvertently made the oscillations look 4x bigger than they were. Explanation at 9:05 into the video.

About VPN sponsors, Tom Scott made a great video detailing how a lot of their claims are dishonest.

I’ve been following Matthias for about 10 years now, and I remember the first time he did a sponsored video I was pretty upset. I thought he had sold himself out. I subsequently have watched all of his videos, especially the ones where he talks about sponsorship. I really appreciate his integrity. And this is a great example of a class act on his part.

Test like this actually make me more confident about buying one of this boxes, I prefer to know the limitations of the equipment I use without having to blow up stuff myself. I love when companies listen to feedback and use it to improve, it's a shame they weren't willing to do so this time, I hope you can get a sponsor who does.

Matthias proved his integrity twice in one day!

There were some good comments on the prior version of this video. 1) The neutral fault: as mentioned elsewhere here, you must use a differential or isolated probe for this kind of testing. Otherwise you're tying mains ground to generator neutral which is a terribly bad idea. Best case that causes a ground loop and will trip an AFCI breaker. Worst case your scope is now a bypass and/or ground reference for the generator and you'll have unknown amounts of current running through the scope ground plane. The test was done incorrectly. I've inadvertently made similar mistakes when checking the output of my gensets and working too quickly, resulting in exciting sparks and breakers throwing, but I blamed myself and not the products. Neutral is not the same as ground!!!! 2) The line noise is the result if the inductive load of the motor. This happens any time an A/C motor starts. The effect on mains is mitigated because the power distribution system acts as giant capacitors. But this is why lights flicker or dim when a large air conditioning unit kicks on. As noted elsewhere, when sitting on a generator, there's nowhere for this inductive load to go and the generator can't spit out enough power instantly to manage it. The table saw is better because the motor is probably not all that much larger than the circular saw, but you have dramatically larger output buffering with those two units than the one small unit, plus the table saw starts slowly. The real point of the 240V on the table saw is for motor torque, not for higher power output. You'll see this same noise on *any* generator - battery or gas. It's not a product fault, it's a use case fault. This is one big reason why large (i.e. >1/4hp) A/C motors should run from *traditional gas* generators. There it's just a spinning rotor - no electronics except for the voltage regulator - so the inductive load gets (partially) sunk into the magnetic fields and there's no electronics to damage. You can hear the two motors (gas and the tool/appliance) fight each other at startup, then run in sync. Generator companies, especially consumer grade, and double especially this new wave of battery ""generator"", are built for common household use cases - refrigerator, lights, TV, not much else. A wood shop is not the designed use case! Sadly their advertising does say "power tools", but their example is a hand drill. And the inductive load of a hand drill startup is far, far less than a circular saw. So sure, they need to be clearer in their marketing, but running a wood shop off of a battery power pack is a highly unusual use case. And construction crews are *not* going to be buying this kind of thing - they're buying plain old gas generators. Even in that use case, the only thing plugged in will be motors - saws, compressors, drills, mixers, etc - which don't care about noise very much. So as long as the genset output is sufficiently protected so it doesn't get killed by the noise (which appears to be the case), then they did things correctly. You've got good material, but you need to better understand what you're testing and what your results actually show before drawing conclusions.

As you mentioned, it is an extremely minor issue, I'm surprised they weren't happy with your proposed warning of not running power tools and sensitive electronics simultaneously... It's still a fairly strong recommendation overall.

Matthias is brutally honest, even if it hurts himself. A breath of fresh air to integrity.

If I needed one of those, I'd still buy one. Better to know the limitations. Which in this case are acceptable in my opinion. Good and honest videos, as per usual.

I like that you called it a battery powered station. Not a generator as many channels do. It drives me nuts lol

The internet needs more people like Matthias. Thank you for all your honest content.

4:14 - so you've built an FM radio transmitter! The drop off in response is a little disappointing, though using a circular saw on a portable battery bank is quite a bit of an outlier compared to the typical case of plugging in fridge, a laptop, and a couple other smaller appliances. Next time I talk to Ecoflow (I might be working on a solar project where they could be a sponsor), I'll be sure to bring this up and see if I also get the silent treatment. Hopefully not!

Seriously, the Ecoflow looks like a well built product as it is. So what if it has limitations? Everything in the world has limits. The important thing is to document it well, and inform the users. Ecoflow needs to get on board with that.

Matthias, you are a rare being these days: A trustworthy man.

The sine wave getting chopped to bits when you massively overload the inverter seems absolutely normal. Impressive the small thing even managed to start it. I suggest a brushless saw for anyone using aux power, they should have soft start circuits.

Your review made me more impressed with the Ecoflow. I'm ok with that limitation and would gladly buy one if the need arises in the future. It seems like a very well built device. As you said, a simple warning in the manual would probably suffice, especially for the whole home model.

I very much appreciate your general approach to issues; you give each problem a thorough effort, as a result we all learn a lot. Keep the videos coming. senior from Ajax

The company I work for makes controls for lots of industrial applications. The noise you are seeing in the output is (as you say at the end of the video) not that uncommon. One of the products we developed had a capacitive dropper power supply originally, but when (in this application) a motorized door was opened on the same circuit it would reset the controller almost every single time. Changed the design over to a switch mode transformer based power supply and the issues went away. In short, the noise you are seeing in the generated voltage is "normal" noise, and it is very much up to the other devices on the circuit to be designed with good enough protection to save themselves from these types of transients. On a positive note, laptops, desktops, phone chargers, etc should all be immune to this type of transient due to being SELV compliant (safety extra low voltage), which requires isolation from mains for end user protection. All devices that use the capacitive dropper power supply shouldn't have end user touchable connections because there's potential for phase reversal (line/neutral swapped).

Integrity cannot be bought.

I use a lot of power tools and sensitive electronics (PC overclocking carpenter...) and I have been looking into a couple different brands of these power stations for off-grid use. Thanks for going in-depth on these units, and thank you for holding to your principals, your content and character speak for themselves. Keep up the awesome work!

I can’t tell you how long I’ve followed you and I also can’t tell you why, but I view almost every one of your videos you put out. I dig your style and the integrity you have is almost unmatched. You are the safe for work version of AvE!

I'm unsure how one would design an inverter to make the waveform perfect during motor startup.

This video summarizes why I been following this channel for so long. Continue with integrity

The problem might not the generator but the saw itself because of how the commutation in those motors work. What you are seeing on the scope are probably resonances in the output filters of the generator. You can probably observe the same messy waveform when the saw is connected to mains. The frequencies will be different but the resonances caused by stray inductance in your house wiring will be visible. It can help to connect a capacitor directly across the motor. (they have special capacitors for those applications with three wires where one wire connects to the motor stator.)

Double respect for 1) not having "should your soul" for ad money and 2) owning up to your own mistakes. Integrity, honesty, and humility are nt popular virtues these days... Thank you, Matthias.

I am so happy that I watched this through. I am slowly setting up a fully off grid wood shop. But I may have some more sensitive tools in there. I had no idea that some tools could cause others to blow out. I wonder if those surge protector power strips would be harmed by this? My thinking is to have everything off unless needed to prevent such issues.

Ok, when you measure AC voltage, it's always a good idea to NOT connect the ground from your scope to the device under test (be it neutral or ground). A safer method is to take two scope probes, connect one probe to the HOT, and another probe to the signal ground (btw, this is not necessarily earth ground and can still have the potential to kill), then use the scope built-in subtraction function to get the desired waveform.

Now I’m curious if more well known brands of battery boxes (Jackery? Anker?) have this problem.

Matthias, man, what a class act you are!!! This is why i trust you before i'll trust others. You've proven your worth, Sir, and it is of the highest value.

Thank you for your candor in your sponsorships. I hope you find one that you feel comfortable representing…and I’m sure this video will work as a siren’s call for high integrity companies!! You’ve build a lot of trust with your viewers by standing up for the consumer. I hope it will pay off for you. Subscribed 🙂

This is why I love the sponsorships you take. The fact that you won't stand behind something you have an issue with not only builds trust with you, but also with the brands who choose to work with you. If a company is willing to let you take their product apart and do tests on it, I respect their product far more than if they just paid someone to say it's neat. I'd expect that behavior from an overloaded inverter, so I suppose that isn't necessarily abnormal, but I would expect overcurrent protection to kick in before the waveform gets distorted enough to potentially damage other devices. I suppose that's why theirs can power much higher load stuff like power tools, where other inverters would just trip when you try to start one up. Maybe a 'safe' and 'high power' mode would work, enabling or disabling the OCP, or at least changing the duration it will trip on, and a simple warning about mixing sensitive and high-power devices on the same battery.

Great video. I really respect you interrogating your sponsors like this and holding them accountable. The reason that sponsorship have become so popular is that they work. people tend to trust the words of people that they like and well trust.

So it's not a big deal because like you say it is common for machines like that to cause big spikes/instability but it's definitely something to be aware of. Still thankyou for being honest and even re-uploading whilst admitting your own mistake.

First video I have ever seen but this level of integrity make me want to subscribe even if I have no idea what kind of videos you make

This is why I enjoy your review videos. You are thorough and honest

Imagine you are a battery company. You intend promotion, and instead you get some of the most thorough product testing anywhere. I can't imagine being mad about that! I would love having that kind of feed back. You can't improve what you don't know isn't working!

I have never seen your videos before, but after watching this, you have gained my subscription! love to see someone willing to stand behind their word and what they believe in! keep on!

I feel like the algorithm knows, because I just watched another video with one of these products in and was immediately recommended this video!

Thanks for this PSA! I have one of their power stations and great information to know! So don't plug sensitive electronics in while using power tools at the same time. Good stuff. I didn't watch through till the end to see if you mentioned it, but I would imagine most portable power stations like this probably have the same issue

I respect your honesty and desire to do the right thing. You are a good person. Thanks for the clarity.

This kind of thing is very rare on RU-vid I think when it comes to product sponsers. Thank you for the insight and integrity. Got my subscription. Looking forward to seeing more.

Very interesting. Thank you for being so honest as to come back and correct the mistake you discovered. It will be interesting to see if Ecoflow will now follow up with you. It was very worrying that they stopped contacting you, it's OK if there was a difference between you and Ecoflow on the severity of the issue you diagnosed. They should not have broke off contact with you, that is a worrying sign about the companies approach to problem solving/customer care. Regarding the other unnamed company that reached out to you to do a review of a solar power generator, you should let us know who they are. I am now more interested in seeing a review of their product than ever, because you do a thorough critical review should not be a reason for them not to follow through with to review there product.

Great discussion, a lot to think about, thanks for putting this up! I can't really imagine a more savage use case for these boxes, it's good to have some data on the ground so we can start comparing them.

Its normal in my opinion, the same issues occur on most switching power supplies when faced with an inductive load that will try to pull all the current in the universe for a split second. I think you're expecting too much if you expect to not see any change in the sine wave during initial power up. Maybe if you had some iron, like a big 110v to 110v transformer and a nice capacitor you could mitigate it somewhat.

You (and others) need to do more videos like this and hold the boardrooms accountable for the money making products they peddle. Thanks for sharing. Cheers

Nice video man! I’ve done a few reviews - never a sponsored video. I was approached a few times by agencies… geeeezzz, the contracts are a monstrosity 🤣

That would require quite the inductor and capacitor on the output of the inverter to clean up the signal in that kind of current draw.

Wouldn’t it be great if product makers communicated with their customers like this. I would feel so much better about buying something with some transparency into the testing processes.

yeah, high-inductive loads will be hard on any inverter-based supply controlled with semiconductors. The instantaneous demand they create is really outside the scope of normal loads. That being said, that can be considered a conducted emission, and (IMO) UL should consider testing for this. These huge battery banks have a real potential use case as jobsite power for construction projects without their own supply, so it's definitely relevant info.

It really sounds like it's not an issue.

Good that you explain on the end of the video what actually was the case, and what is the real issue, and that it often occurs with such high power tools.

Funny timing with the revised version, something like half an hour ago I watched the old version

Matthias is a guy that puts value on his integrity. Ecoflow should feel honored to, even with a minor flaw that he notice, still doesn't bash it, and is honest about how it would only affect costumers in a few corner cases. No product is perfect and I think it is still a good battery, and being aware of this limitation, IMHO, doesn't affect the product reputation.

I was surprised this video wasn't sponsored by established titles like every other video I have seen this week.

Fascinating. I have not watched any of your other videos as far as I know but I suspect I will want to do that in the future so I subscribed. It is probably hard to get an inverter to be nice under those circumstances, in the grid there are so many other loads that helps in sinking the noise. One could add some filtering but that would likely include lots of copper and increase both the price and weight of the device. Anyway, I enjoyed your very earnest way of dealing with this matter and your priorities in selecting a sponsor. It is sad and common to see sellouts so this video made me quite happy. Thank you!

Wow the turnaround time between the two videos was very fast. I just watched the first one this morning, and here's a new revision in just a couple hours.

Respect for you for your honest review.

"Peddling mattresses" I've never heard anything more true about YT sponsors

This guy is great...subscribed back when I was into woodworking and I still stay subscribed for stuff like this

I appreciate your honesty and fairness. One question though: what happens to the waveforms when the saw is on normal line power without the battery box? Is it possible that the oscillations are due to the sudden high inductive load?

Yep, that's pretty typical for high frequency inverters... best to keep large inductive loads on low frequency inverters if you can.

So much of this video is over my head but it’s good to know about. Commented and liked for the algorithm.

Sir you are a very rare thing to find these days, a man of integrity. My hat off to you.

Integrity. What is more interesting is the company in question did not challenge your results or have someone review your process to ensure they could replicate your results. Or if they were aware at least compare results; at least I didn't get the impression they did. It is still an interesting issue to be aware of.

Massive respect for being honest and having integrity.

The 8 bit guy needs to watch this

"Pure Sine" inverters like this (and like UPS' and the like), along with the inverters for the 3-phase motors in EVs all work the same way. They use a microcontroller to make a high-frequency PWM signal to switch a pair of MOSFETS (or IGBTs). This is because FETs are almost completely efficient when on and off, but can't handle analog voltages in-between. So the signal is switching on and off at a value somewhere in the multiple KHz range, and it's period is adjusted to form a 60Hz sine wave, which approximates a sine wave. This is then smoothed with an inductor to fill in any switching gaps and make it a full sine. With massive inrush currents like your circular saw is introducing, it's overwhelming the inductor's capability to smooth the PWM signal, as the current is pulled out of the inductor before the next cycle can introduce more. Because of this, the output sees (momentarily) the raw PWM signal. The only way to "fix" this is to massively increase the size of the inductor to cope with this one-in-a-million inrush. Sensitive electronics usually use a capacitor on the input to smooth the DC ripple from their rectification anyway, which would entirely negate this "noise", but because the Kill-A-Watt (and devices like it) require interacting directly with line voltage to measure the throughput, it can't use smoothing components on the line. Incidentally, the other inverter strategies used by UPS' are "Stepped Approximation of a Sine", which uses capacitor and resistor ladders to create a very coarse sine-line signal, and the cheapest units omit the ladders and just outputs raw 60Hz square waves, letting the cabling act as an inductor to smooth the power a little.

thank you for your honesty and intelligence

Matthias is so rigorous with his methodology. It's great! Keep doing what you do, bud.

Integrity, instant sub to ya. This is also very useful information as I would like to do solar one day. Useful to know I should not hook up motors and electronics in the same circuit. Although that's generally good advice for mains circuits too.

Good on you for having a backbone! You’re one of the good ones!

I love this. Ecoflow had no idea they were sending their products to someone who actually understands electronics. Maybe their marketing team learned a thing or two about what they are trying to sell.

50 amp rms inrush current at 120V rms is 3000 watts. Would oversizing your ecoflow system to facilitate this inrush power mitigate the problem? Also is the OCP on the ecoflow not tripping the 50 amp inrush because its relay curve response time is too slow?

I appreciate this. There are also lots of devices being sold these days on online sales platforms that are 100% dangerous and no one seems to care.

Lol ! Welcome to the club. Another vendor sent me a pre-production box, and when it faulted he offered me a swap, sent it back - never heard from them since. Beware of the educated tester .....

Thanks for your double integrity. Even if the saw is drawing out of spec, surely the least the company can do is modify their design so that even if they don’t clamp the excess voltage, it fails gracefully. Just because other inverters also failed to fix the problem doesn’t make it OK. I’d also be curious what the startup waveform looks like on a wall outlet.

Always better to be pissed off than pissed on.

Thanks for the video and the honesty! Glad you saw a flaw in the test and owned up to it. We do a lot of this kinds of testing maybe why some sponsors don't call me, I have been taught to be totally honest I will not BS users to get sales for a company no matter how much they pay.

Thanks Matthias, this is the exact reason I always love ur videos. I was on fence on buying EcoFlow now just might hold off the purchase.

A low-pass filter on the output cable made with a ferrite core would likely solve the problem. Simple, cheap and effective.

I'm happy never see another ecoflow sponsored video on YT again - nothing against you Matthias they just flooded the platform

I appreciate the video and admire your honesty. I have been a very happy eco flow customer for about a year now. I broke my river unit through my own stupidity and it was still replaced for free. Like you stated this is an issue I expect from most inverters and is not a big deal to me. I expect that a large inductive load on a mains circuit has the potential to also damage sensitive electronics.

I have to find an oscilloscope to see what my Victron Multi plus II does with a load like that? I never thought about this till now. When my RV AC kicks on (I don't use it much on solar just really hot days) is the inverter still giving clean power?

Matthias, I guess they didn't realize you were an actual engineer. Their loss. I guess that's the price you pay for honesty and integrity. Excellent video by the way.

It's not often YT'ers have enough integrity to call out a sponsor when they see a potential flaw in their product(s). Thank you very much for sharing all your findings, you just gained a lot of respect from at least one viewer! 😎

Idk if I am going to watch anymore of this guy's videos but I subbed and commented for the integrity

Thank you Sir! Always a pleasure to enjoy your time and experiences!

You pissed off a sponsor again?

I love that you gave that company the benefit of the doubt by saying they “ gave this power supply to some random RU-vidr.” And not like “a major player and former EE at RIM.” Even as a non-engineer myself I know who I’ve been watching for the last many years. Never doubted your integrity!

If all sponsorship arrangements were approached with this kind of honesty, we would all be a lot better off. Good on you for sticking to your principles Matthias. 👍

Your integrity is impressive! I'm in awe.

This is not integrity, it's ignorance. Of course this will happen with an HF inverter. What you need is a high quality LF inverter that can handle power tools. I'm surprised that little hf inverter circuit even powered that saw! That's insane. And I have shown how to actually break these units and some of the ground neutral bonding issues present when using the double voltage hub. But putting a massive inductive load on such a small hf circuit is going to cause this issue regardless of who the manufacturer is. Use a nice victron with a surge capacity design for your application and you won't have an issue. I try to critique these products and break them on my channel every single day, but this "critique" just shows a lack of understanding of these circuits. Trying to filter that massive surge is just unrealistic. Try an LF inverter instead. And one large enough for the inductive load you wish to power.

I am looking to invest in some of this. Saw this and you for the first time. Subscribed just because of your integrity. Thank you.

that is a **VERY** dificult task for an inverter to handle

Once again, the engineers at companies that might work a sponsorship with you should be quite pleased.

Thank you for the heads up! I just got one of these so I will make sure to avoid using power tools on it while also powering electronics.

you just gained a subscriber. Awesome explanations and honesty. Great job

Good video :) . This is the main reason that I run 3 invertors here. A sinewave one for the sensitive appliances, and a pair of modified squarewave ones for the heavy tools / machines. In all these 28 years, there has never been a problem :) .

I love honest smart kind people like this guy.