Chinese high voltage modules on eBay massively overrate their output

[Ben321]

I got a so called "400kV" module on eBay from a Chinese seller. Barely could make an arc three quarters of an inch long. Got another one labeled "20kV", but it could barely make an arc a couple mm long.

[PartialDischarge]

Cmon, everything you get on ebay/ali is of dubious quality, everyone knows the game by now. Good pictures and thats all.

[Ben321]

Cmon, everything you get on ebay/ali is of dubious quality, everyone knows the game by now. Good pictures and thats all.

Usually only the Chinese eBay sellers have a problem with this. Most other sellers (especially if selling from the US or Europe) sell you the actual equipment they are advertising and will tell you if it doesn't work so it's being sold as-is.

[ataradov]

One is selling as an individual seller and using eBay for its original purpose, and the other one is using eBay as a store front.

Their standard excuse is that "400kV" is not specification, but the model number. Some will list the actual specification in the description, others won't.

It is not like this is new. I'm sure European sellers (re-)sold "2000W" stereo systems in real retail stores.

[Berni]

That was always the case.

Things like 10000mAh 18650 cells, single AA battery powered flashlights with 10000 lumens...etc Every time you see an absurdly large number on a chinese product you can assume it is made up.

[Ben321]

Their standard excuse is that "400kV" is not specification, but the model number. Some will list the actual specification in the description, others won't.

Here's an example of the product title of one of these.

DC 3v-6v to 400kV 400000V Boost Step-up Power Module High-voltage Generator

It actually shows the voltage stated both in kV (as 400kV) and in V (as 400000V), making it very clear it's not just a model number but intended to be read as a specification by the purchaser. The device falls far short of that specification though.

[ataradov]

"400kV 400000V" is a full model number. Your interpretation that this is a specification is wrong. Basically, don't believe random writings when paying way below what something like this would normally cost.

[Ben321]

"400kV 400000V" is a full model number. Your interpretation that this is a specification is wrong. Basically, don't believe random writings when paying way below what something like this would normally cost.

Except it says DC 3v-6v to 400kV 400000V, which clearly is a description of the device, indicating it takes a voltage in the range of 3v to 6v DC, and outputs (supposedly) 400kV.

[ataradov]

"DC 3v-6v to 400kV 400000V" is even a fuller model number. Complicated, I know.

Again, what did you expect buying $3 module? If you actually apply 400 kV to that package, it will blow up. It is pretty clear it can't be 400 kV from simply looking at it.

[magic]

Whether the seller says it's a "model number" or whatever, it's misleading advertising.

On AE you could probably get a refund, but it would be helpful to be able to demonstrate comparison with a similar properly functioning device, or some measurement.

[Zenith]

I got a so called "400kV" module on eBay from a Chinese seller. Barely could make an arc three quarters of an inch long. Got another one labeled "20kV", but it could barely make an arc a couple mm long.

And were you surprised?

[Ben321]

I got a so called "400kV" module on eBay from a Chinese seller. Barely could make an arc three quarters of an inch long. Got another one labeled "20kV", but it could barely make an arc a couple mm long.

And were you surprised?

Not particularly surprised. The 400kv from a tiny high voltage module seemed very suspicious.

[TimFox]

"DC 3v-6v to 400kV 400000V" is even a fuller model number. Complicated, I know.

Again, what did you expect buying $3 module? If you actually apply 400 kV to that package, it will blow up. It is pretty clear it can't be 400 kV from simply looking at it.

One can expect a language barrier when dealing with foreign sellers, but we have all agreed to SI labels on electrical units.

[Zero999]

Has anyone seen a real data sheet for one of those modules?

What are they normally used for? I can't see I've ever seen one in a real piece of equipment such as a gas boiler.

[BrokenYugo]

I think they're cheap "stun gun" modules, that's probably where the ridiculous number comes from, though a quick look on ebay suggests the bullshit arms race has those now making claims in the low megavolt range.

[CatalinaWOW]

Their market is people who can't look at the output terminal spacing and see directly that the advertised voltage could not be true. 

[floobydust]

Naive people buy purely on a spec or number- without questioning it.
One store stretches that number, then another store does it etc. and pretty soon it's MEGA.

[dobsonr741]

Chinese “brands” provide entertainment value, that’s all. Don’t read more into it.

[Amper]

Does anybody have more info by now? An actual datasheet?

Im looking into using them for some experiments, i want to use one 18650 cell per module and control it via TOF plastic fiber to be able to put them into series for high voltage generation.

Of cause its not 400kV but i suspect them to go up to 20-30kV DC, just a proper datasheet would be nice to have a good idea of what to expect.

[Andy Chee]

No datasheets, the best you're going to get are Youtube teardown videos

[Amper]

Oh, thats a good teardown at least, thank you!

[Zero999]

No datasheets, the best you're going to get are Youtube teardown videos

Wow, that's a long video, for something so simple.

To summarise: it's a blocking oscillator, driving a transformer with a multi-section secondary winding, to ensure the voltage between neighbouring turns doesn't exceed the breakdown voltage of the lacquer insulation and a capacitive diode multiplier on the output.

[vsmith]

I love it. Thank you, intrepid tear-down person! "Not a very..brilliant idea...I should have used a pair of gloves...now this acetone is penetrating my skin!"

Also I was wondering if soaking the module for several days in acetone was going to damage the components inside the epoxy. Now I know.

Truly entertaining and very well shot video. I laughed and I learned things! The internet at it's best.

Vic