You can always open up any unknown charger and check it visually to start with. If there is no place on the circuit board where you see a separation of some of the circuit traces from the rest then its isolation may be bad, dangerous. If you do find a decent separation then you can move on to look for a capacitor bridging the two sides. There may not be one but if there is then it must be a safety capacitor (which will have more markings). You can post picture if unsure of anything.
The problem with opening the charger is that it often "destroys" it.
I plan on testing many usb chargers and I will be looking at the suggestions posted here.
They are expensive enough to be good, I am very curious about them.
I have ordered one and put the rest on my shopping list and will probably order them during the next week. Due to the price I have to order one at a time, if I get two in one package custom will give me a $22 fine.
Great! 
They sure have some fancy compliance markings written on them. Hopefully they are legit. Looking forward to your tests!
It is easy enough to print the marks on the charger, it is much harder to live up to them. If the marks are legit there is some serious testing behind them.
Just be aware of the time frame, I will not publish any review soon. At the current time I have about 10 usb chargers in queue and I doubt I will publish much more than one each week (I may get time during Easter to publish a bit more, but them I also have other stuff).
I just want to tell you how much I appreciate your excellent reviews. I find them very useful. It’s nice to have factual information upon which to base purchasing decisions.
HKJ - Thank you for the clarification on CE & UL testings!
All of them are on the way.
Some usb chargers do get hot, I have just tested a multiport one that got above 100°C on the plastic.
Ouch, that is hot! Looking forward to the reviews, in a month or two.
God helg!
It is hot and probably means it will get a bad rating (I am still missing the 5000 volt test and the tear down).
A month or two before I publish the first one is probably correct, but the last one will take a bit more time. I do have about 10 in queue at the current time. It looks like I am going to test a lot of usb chargers in 2015.
I am still open for suggestion about other chargers to test. The most interesting is not chargers that is expected to fail (i.e. models below $3), but cheaper chargers that are good.
Thank you. In Denmark we usual says "God weekend", but it is only valid for Saturday/Sunday, not for something like Easter.
For me that often means time to write the reviews and do the manual part of testing stuff (The automatic part is running 24/7).
Conrad has some interesting high-power USB chargers. They are pretty big/popular in Europe, so some reviews of the chargers they sell might be interesting, since they are very easy to source in EU and pretty cheap.
For instance a 24W 2x2,4A charger:
Or a 25W 5X charger:
Can you test one of the Anker chargers? I've been quite pleased with the 5 port, 40 watt model
I have ordered all 3 chargers, depending on what sequence I publish in, it can be a couple of months before the review is published.
Thank you for the list - I like it just the way it is.
We are currently debating this topic on mysensors.org (see thread ) and someone posted a link to your excellent reviews. We were wondering if the meanwell GS05E-USB or GS05U-USB are safe as it is almost the only one to have OTP. Meanwell is generally a good company and the price is very reasonable.
As we lack the equipment and expertise to test it, we would be grateful if you can give it a go. It is available from :
Mean Well GS05E-USB
http://www.mouser.com/ProductDetail/Mean-Well/GS05E-USB/?qs=Uzd%2Fwh%252bZzhAiQfliv1zavg%3D%3D
I do have a thread to put review wishes/request in. There is two problems with the above:
1) I have a queue that is a couple of months long.
2) Shipping is £20 from mouser EU.
I would expect meanwell to make good products.
http://www.tme.eu/en/details/gs05e-usb/mains-power-supplies/mean-well/ - much more reasonable - 8 EURO shipping and 7.20$ for the product. It seems like it is a new product and will be available through many more shops as new shops get it every day.
I understand the queue… But as this charger is unique (at least in what I looked at) and priced well below other chargers of this caliber it might be in the benefit of the community to maybe give it priority. If not, we will wait patiently…
I really can’t see what’s so special about this charger…
Meanwell is a good company but on lower-end products they tend to use dodgy CapXon capacitors. For example APC-16-350 uses Samxon/CapXon capacitors for input/output filtering and i really hate those CapXon’s (KF series) as they go bad even in highly undemanding applications. What’s more irritating, psu is potted making capacitor change very difficult if not impossible…
The difference between this charger and any other charger we looked at is that it lists Shortcircuit/Overload/Overvoltage/Overtemperature protection. No other charger I looked at has all 4. I only had good experience with meanwell - I am no expert but all their stuff looked well made, not like a 5yo did the soldering and no components that looks like they were recycled. However, I used different lines and as always, YMMV.
At mysensors, we need reliable powersource that will be reasonably safe to keep inside a box or inside the wall cavity. Because of that we need a charger that has OTP. Many members use the square Chinese chargers that failed almost every test. We are looking for something that:
- Can be bought from the source or undisputed distributors
- Normally priced - each of us uses over 10 chargers only for the sensors. a 20$ sensor will make the charger cost more than the sensors….
- Has as many protections as possible - as I said it needs to be in a box or behind the switch
- reasonably clean signal - the arduinos/nrf are not very fond of noisy signal.
If you can recommend any other charger that fulfill even almost all these requirements, I’ll be very happy to use it.
When i said nothing special that excluded typical low cost china PSU.
All that protection is based on controller IC capability. Most of controllers are internally protected for these conditions, so nothing special about that. But beware that meanwell states OVP 105-200% rated output voltage.