Review, teardown and analysis of Charging Essentials USB wall outlet

(UPDATE: March 2, 2015 – I’ve picked up a pair of the newer tamper-resistant versions of this wall outlet. A review and teardown on that unit is coming up; stay tuned!)
(UPDATE 2: May 29, 2016 – Scratch that on the first tamper-resistant model; it had the same performance as the one mentioned here. Also, Costco has released a 3.1A version of this outlet, and is currently under review.)

About a week ago I bought a set of wall outlets from Costco that integrate two USB charging ports into a standard Decora-type receptacle. It’s marketed to replace your traditional AC adapter, allowing other appliances to be plugged in while charging your portable electronics.

The outlet is made by Omee Electrical Company, but curiously enough this particular model, the OM-USBII, wasn’t listed on their site. The packaging itself bears the name Charging Essentials, with a logo that looks like a USB icon that’s had one Viagra too many. The packaging states that the outlet has:

  • “Two 5VDC 2.1A ports for more efficient charging in less time”
  • “Smarter USB charging with special chip designed to recognize and optimize the charging requirements of your device”
  • “Screw-free wall plate snaps into place for a more clean, modern appearance”

The second note is of particular importance to me. If it’s true, that means it might be using some USB charge port controller like TI’s TPS251x-series chips. But I’m not one to have blind faith in what’s written on the packaging. Let’s rip this sucker apart!

The outlet has a snap-on coverplate which may look sleek but could hamper removal of this outlet later on if needed. I was curious as to why one couldn’t just use a regular screw-on coverplate, and it turns out it’s because the mounting flange doesn’t have any tapped screw holes; you physically can’t use screws on this because the manufacturer didn’t want to go to the effort to make holes that can accept screws!

The casing is held together with four triangle-head screws in a weak attempt to prevent opening of the device. I had a security bit set on hand so this posed no hindrance to me. Upon removing the cover, the outlet seems rather well built. However, after removing the main outlet portion to reveal the AC-DC adapter inside, I quickly rescinded that thought.

The converter seems relatively well-built (at least relative to some crap Chinese power supplies out there). Some thought was put into the safe operation of this device, but there’s almost no isolation between the high and low voltage sides, and the DC side of this adapter is not grounded; the “ground” for the USB ports floats at 60 volts AC with respect to the mains earth pin. The Samxon brand caps are also pretty disappointing.

As for the USB portion of this device, I had to remove some hot glue holding the panel in place. After a few minutes of picking away at the rubbery blob, I was able to pull out the USB ports.

… and I found LIES! DIRTY LIES! There is no USB charge port controller, contrary to what the packaging claims. It just uses a set of voltage dividers to emulate the Apple charger standard, which could break compatibility with some smartphones. Ugh, well let’s put it back together and take a look at it from the performance side of things. At least the USB ports feel pretty solid…

To measure the voltage-current characteristic of the outlet, I rebuilt my bq27510-G3 Li-Ion gas gauge board so it had better handling of high current without affecting my current and voltage measurements. The reason I used this is because the gauge combines a voltmeter and ammeter in one chip, and by using the GaugeStudio software, I could create easy, breezy, beautiful V-I graphs.

Using a Re:load 2 constant-current load, I slowly ramped up the load current while logging the voltage and current data to a CSV file for analysis in Excel.

overall vi graphThis charger’s… okay. It has surprisingly good regulation up to 2.3 amps, but after that point the AC-DC converter basically brickwalls and the voltage plummets to 3 volts. That said, this also means that this outlet is not a set of “two 2.1A USB ports”. You can charge one tablet but you won’t be able to charge a tablet along with another device simultaneously.

Bah, I’ve had it with this wall outlet. Looks like this one’s gonna be returned to Costco in the next few days. This outlet may be adequate for some people, but for me it’s a disappointment.


  • Solid USB ports
  • Good voltage stability (up to 2.3 amps, enough to charge ONE tablet)
  • Apple device compatibility


  • Annoying coverplate design
  • Does not meet rated current output, will not charge 2 tablets or 1 tablet + another device
  • Does NOT have a “smart charging chip” despite being stated on packaging, some devices (eg. BlackBerry) will refuse to charge from these ports
  • Power supply for USB seems cheap
  • USB port is not grounded – if a short-circuit happens inside the power supply it can be a shock hazard to you

74 thoughts on “Review, teardown and analysis of Charging Essentials USB wall outlet

    • The first 2 recepticals I installed, the usb’s died. And so did the green lights. Now the replacements from Costco have TR tamper resistant, on the outlet. But the usb ‘ s do not charge even with the green light on

      • I’ve found that the new tamper-resistant outlets have the green LED powered directly from the AC mains instead of the 5V USB output, which I think is a bit sneaky since it’s no longer possible to visually confirm if the USB outputs are working or not.

  1. My wife bought this and first thing I noticed is that it is not TR (tamper resistant). For residential installation it needs to be TR,
    The picture on the package also shows it installed “in the kitchen” right next to a stove top. It is not 15-amp split duplex nor 20 amp so it is not suitable for that installation.
    I would like to know, what standard the ETL-listied was verified to?

  2. One of the two that I installed nolonger works. The outlet has power and works but the USB ports do not. The annoying green led is not on anymore and it does not change any device. All the connections seem solid. This is after maybe 2 weeks of being installed. Waste of time and money.

    • Jason, great write-up! Thanks for doing all the in-depth testing. I too have a VERY hard time believing anything written on the packaging of any electronics goods, this pkg being no different.
      I understood the specs to indicate that each wall outlet had 2.3 amps max to give so if two usb ports were being used then that’s all you’d get between the two. Glad you tested this to confirm.
      I also had my disbeliefs about the smart charging indicated on the pkg. I was surprised to hear that the ports are not grounded.
      I am disappointed to see how poor these are overall. I have installed 4 of these so far but have not had a chance to use them much as of yet.
      Not happy to hear one customer’s comment that his usb ports have already stopped working after only 2 weeks.
      What about surges or spikes? Do they have any protection?

      • There is a single MOV (metal-oxide varistor) for surge protection, thermal cutout and a small glass fuse. I don’t think there’s any DC-side protection apart from what’s built into the switch-mode power supply chip.

      • We have purchase 8 packages from costco and within a week 2 the usb green lights have shutoff and now no usb charging. Was a great idea, only if they actually worked.

      • I bought one and it worked long enough to charge my phone once. Now it won’t charge and the green light stays on. I bought two packages from Costco but only tried one receptacle out to begin with… I’m taking them back. Useless product. I pulled it out and put original receptacle back and went to the “old” sub block again.

    • I am having the same issue with both devices. USB worked for a week or two tops. Now both USB outlets on each receptacle do not work and the green light is off. I will be returning.

      • I paid my electrician to install a whack of these units as part of a whole-house reno. Within a month most of mine have also stopped working … although if you reset the breaker, they work again. Not impressed. Now I need to pay my electrician to remove these pieces of crap and reinstall proper ones. Wonder if Costco will cover that bill??

  3. I just purchased same the plugs from costco and installed one. I have an Apple 5c and connected to the charger for a refill and it quit after about an hour. No green light and not charging anymore. The 110v outlet still functions though.

    • I had this happen to me recently after using it for about 2 months.
      I had to go to the breaker box and switch the power for the outlet off and on for the green light to come back on. Still works.

      I’m wondering whether to return this too, but no longer have my receipt for the item. Shouldn’t be a problem though seeing as it is Costco.

      • I had one that didn’t reset when I threw the circuit breaker off and on a couple of times, figured it was toast but didn’t bother to pull it to return finely tried the breaker reset again and this time left it off longer and it reset. Based on this tear down commentary these are going back.
        If these guys want to keep selling them its obvious they need to meet the basic spec requirements to charge all devices and a reset button at the outlet is needed too.

  4. Hey, I also got this package, and both worked fine for about a month, until the USBs on one just quit. I don’t really want to bother ripping both out of the wall to return them just because one of them isn’t working. The regular plugs are still fine, so it’s no worse now than the outlet I replaced!

    I was hoping to take it apart to tinker and maybe fix it, but I don’t have the triangle screwdrivers, and the sets are expensive, but singles are all over eBay. Can you tell me what bit size it is? It’s gotta be either 2.7 or 3.0 mm, but it’s hard to measure to that much precision. Thanks.

    • I returned this outlet a while ago so I can’t measure what bit size the screw heads were. The bit I used was a 2.0 mm one from a video game repair kit, but it was a a bit too small for the screw head (I damaged that screw bit taking the outlet apart), so I’d say to try a 2.7 mm bit to be on the safe side. Alternatively, get one of those security bit sets that includes a bunch of other bits like Security Torx and whatnot, as they could come in handy later on.

      • Yeah, gotta figure out where to buy that stuff… Even eBay only seems to sell them in sets with only one triangle bit. I already have torx and hex bits!

    • Hey Jon
      Go to your breaker box and try switching off-on the breaker that drives the outlet. Your USB ports should come back up – it happened to me one time.. I think there’s some circuit that just gets tripped to prevent an overload of sorts. Silly that there isn’t a reset button like a GFCI outlet would have.

      • Thanks Kenneth, I should have tried this before posting on here, when I saw your previous comment regarding this. Yes, that did the trick, thanks. Very annoying, and as this article suggests, a bit sketchy for a design… Oh well, found out it’s too late to return them, so they’re staying in there!

    • It’s Costco.. you don’t need to take them both back. Take back the one and explain, they will give you a full refund. Costco is great like that and why I never hesitate to buy anything there.

  5. Bought a pack of 2. One failed after 2 months. Plug sockets work. USB green light off. No power from the USB ports. Expected better from Costco Canada…

  6. I wonder how much of a current it continues to draw/use (waste of energy) when USB is not used at all. Any idea or anybody tested this out? Normal outlet vs Outlet with USB must use some energy even when not charging.

  7. I bought one a few months ago but never installed it. After reading the comments, I probably will return it unopened. By the way is this device surge protected?

  8. This is a great breakdown! Thanks for the information. I had the same issue as others had posted. Plugged in a Samsumg Galaxy Tab 3 and an iPhone 5s one night and the next morning the USB power indicator green LED was off and nothing was charging. Unplugged everything but the LED never came back on. I took the advice of Kenneth. I turned off the circuit breaker for the receptacle and then back on and presto – Green LED back on, charging again. Definitely not recommending this unit for anyone. I am too lazy to uninstall and return to Costco. If it keeps happening I will rip it out and return.

    It is sad to hear that they are false advertising about the 2x 2.1A USB ports and about the smart charge circuit that does not exist.

    Question for Jason – have you run across a worthy receptacle with 2 smart USB charging at 2.1A?

    • Glad to hear that my blog post has helped many people looking for how well this USB outlet performs!

      I’ve been looking at USB outlets from reputable manufacturers like Leviton, Hubbell and the like. However, I have not purchased any so I can’t make any claims as to their efficacy.

      Leviton makes some pretty promising outlets with 3.2-amp or even 4.2-amp outputs, and also advertise using a charge port controller (that is, what this Charging Essentials unit lacks). One unit on Amazon ( looks very appealing, and it even supports normal Decora coverplates!

      I’ll probably buy some of these units and do the same sort of teardown/analysis on them; I am curious to see what choices they’ve made with their design. Stay tuned!

  9. Great review!! But to bad I read your tear down to late! Anyhow after exactly 2 weeks of use the green light went out and we have no more power to the USB ports, unbelievable! Here we thought we where saving $20 bucks, boy were we wrong! Thanks again for the GREAT review!! Cheers!

    • Bought the same set of receptacles at Costco two weeks ago , February 2015. USB ports worked great while they did work I guess I have to go buy new receptacle ( better quality) to replace this one before I bring it back. On a a good note , I’m lucky I didn’t install both

      • I just installed one for a friend on March 5th, 201. They picked it up from Costco. It has the new tamper resistant (TR) shutters (which I find horribly annoying). The USB ports were able to charge an iPad mini and an iPhone 6 simultaneously. I notice that people are reporting trips – would be nice if they reported what was plugged in at the time. I have had only 1 trip – this was with a samsung Galaxy Tab 4 8″ and an iPhone 5s at the same time. Trip occurred after a few hours. I was able to reset the USB ports (Green Light) by turning off and on the breaker for the receptacle. I have been using it for several months since reset but I avoid connecting the Galaxy Tab (use wall wart instead).

  10. Ordinary people will love the clean look of a screwless faceplate. Ordinary people will not have to remove the faceplate often and will find that a small flat screwdriver will be perfect to remove the darn faceplate. Get a grip man.

    • Thank you for your feedback!

      Yes, the default screwless faceplate will work for most people, but my concern with it is the lack of threads in the flange that would allow for use of alternate faceplates; that’s all.

      You need to realize that my review is focused more on the electronics and performance of the outlet (this is an electronics blog after all), rather than the external appearance of the unit.

      • I got a pack of 2 at costco last week for $23.99. I like the screwless faceplate. I kept my receipt. It charge my USB iphone juice pack well so far. I’ll let you know how fast it charges my ipad 2.

  11. Wish I would have read this before I went and bought, installed and then had to remove because the USB ports stopped working at all.

  12. We installed in our kitchen drop zone with a light switch for the area. Electrician used a double face plate for the outlet and switch which was problematic because of those face plate screw holes – luckily slightly hidden. Ours failed/tripped after two weeks, too (USB) – thanks for info on resetting breaker; will try in the morning.

  13. You can buy screwless Decora double face plates. I don’t understand all the negative posts about this thing. Mine works perfectly. I installed two at a friend’s house and they’re loving them.

    • That’s not the point. The lack of threads means you have *no choice* but to use the screwless coverplate. If they were threaded, then you could use either the default screwless coverplate, or opt for another coverplate that matches the room’s decor. That’s all.

    • Whether or not the faceplate is interchangeable may be an issue for some, keep in mind that this blog focuses on the electronics of the unit. If you want to debate about changing the faceplate, save that for a home improvement forum. Get a grip man.

      • It does focus on the electronics. But some members keep crying over the faceplate and the screws. I have nothing to to with that.

    • Just installed 4 of these. 3 of the USBs failed to charge within 1 hour of installation. Is Costco aware of these feedback.? Why are they still carrying them ?

      • I have no idea why Costco still sells these darn things. When I returned the first (non-tamper resistant) outlets, the customer service rep was already aware of a large number of these outlets being returned because the AC-DC converter shuts down without warning.

  14. Got the same one. USB port trips all the time. It’s like it doesn’t want to charge overnight or something. Only one device plugged in too. Not like I’m giving it a heavy duty test. It was a pain to install because of the clearance required, lots of squished wires. Will be returning and looking for plug in multi charger instead.
    Thanks for the confirmation that this is a waste of material.

  15. Just purchased a set from Costco, The only problem I’m having presently is plugging a cord into the outlet usually my toaster ,seems to be very hard to to go in. Anyone else find this problem.

  16. I can’t get the USB outlets to charge at all. Even when nothing else is plugged in. Can you provide any assistance or tips?

    • Hm, haven’t heard of any reports of the outlets not providing power under any circumstances. Just to rule it out, do the regular 120VAC outlets do provide power? Also, are you using the newer Tamper-Resistant version or not?

  17. thank you so much for your detailed breakdown and review – as well as the Leviton info.
    I was planning on getting the Costco ones but now I’ve decided to get the Leviton ones (Home Depot has them) – primarily for the charge port controller

  18. I reviewed your well written analysis of this wall unit with USB.
    I think you are spot on everything Except the point of charging 3 tablets or devices, it’s been a working for me for a couple weeks with 2 devices at the same time.
    Thanks for you input It was great!

  19. I see your test results indicate the inability to charge more than one tablet. Does this mean neither device will “ever” be charged or just not in the usual time frame expected/hoped?
    What were the actual results when you attempted to charge said devices? How did they compare to your expected results?
    Would this still be efficient enough to charge phones or MP3 player?
    What is the likelihood of a short in the power supply resulting in a shock? Could this pose a hazard to little fingers (the regular outlets can be covered with baby proof(less) socket covers)?
    Sorry for the grilling!

  20. We’ve purchased 4 of these, installed two vertically & they are still working. Installed 2 horizontally and like everyone else’s comments, the USB quit charging and the green light is no longer on. My question is: Do they have to be installed vertically to work? Anyone else have this happen? Thanks!

  21. Bought mine last year… worked great for about 8 months, but now the USB port is dead. What a hassle, have to remove the whole unit to replace.

  22. Now I am fustrated. I want to buy a “quality good one” and am willing to pay more, but except for this one and only quality scientific review and internal analysis, all others reviews and products are junk. I do not want to buy a box with two usb slots which destroy my devices. I guess there is no “quality” product in the market. Yes, I want 5 volts when charging 2 items. fustrated!!! and giving up.

  23. I got them too, piece of shit, after using a full afternoon to install them , one of outlet ‘s 2 usb died, another one charging my iPhone , but the touch screen doesn’t work ,wtf.

  24. I recently installed these which i bought back in 2015. The USB has been working great. However i pulled in an extension chord with a surge protector and it was all good. When i pulled out the extension chord i saw a small spark and it blew the fuse out!

    Just wondering if this thing was mention to have an extension chord plugged in?


    • That is certainly an odd phenomenon. Unplugging an extension cord definitely shouldn’t cause a fuse to blow.

      Did you mean the circuit breaker at the panel, or the fuse inside the USB outlet? The only thing I can think of that would cause a circuit to go dead like that is if that outlet is fed by an AFCI (Arc Fault Circuit Interrupter).

  25. Great review. I’ve noticed a lot of so-called 2.4A or 2.1A usb chargers split the current between two ports. I wouldn’t mind if the advertising were clear and the device were marked to indicate that one can supply 2+A, but the other is limited to 0.5A.

  26. I just bought this and thankfully checked this review before opening it. I’ll have to return it, I guess. I’m just looking for something that does what you’d expect it to. A normal wall outlet with USB ports that don’t have garbage charging rates. Apparently, that’s asking too much.
    Is there anything you’d recommend? Everything I find on amazon is either garbage or crazy expensive. (Regular outlets are like less than $5, and add a couple usb ports and they just jack it up like crazy!)

  27. I plugged both my iPad and iPhone into one of these and had the issue everyone has been talking about. USB parts stop working. But did find that by killing the breaker and letting it sit for a while the outlet reset. So now I just plug my iPad into the regular socket using its charger and the iPhone into the USB port.

  28. Just found this. Thanks for the info you provided in the tear down and thanks to those who mentioned shutting the breaker and waiting a couple of minutes before switching it back on. I thought the usb ports had died but this did the trick. I bought mine over a year ago and don’t have the packaging or I’d take them back. I think the idea of a USB port on the receptacle is a good, but over time as we require more and more power for devices, you’ll end up having to replace them anyway so going forward I’m not going to buy anymore and will just buy bricks with USB ports as to avoid the hassle of having to change them (receptacle) out down the road. Costco does seem to be selling a lot of junk these days though which is concerning to me.

  29. |Good review. Installed one of these and it worked well for a while but then failed to charge USB anymore. It did, however, have the USB ports oriented correctly while all the new replacements I can find, have the ports oriented vertically which means that many 115 volt plugs block them. Just another technology annoyance grrrr

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