Cheap BangGood 18650 charger, is it really safe?

[patrikcarlsson]

Hi everybody! New here on the forum!

I will try to keep this short. I recently watched Dave's cheap mobile charger teardown, which I guess all of you guys here have already watched, if not, here it is! http://youtu.be/wi-b9k-0KfE

Also, I have watched some other YouTube videos where they tested the flammability of the plastic used in these Chinese electronics, and the lack of pretty essential components for a safe product. I just tossed all my cheap ebay-chargers I had laying around, and I will go out and buy a proper CE-marked phone charger tomorrow. The problem is that I very recently got a 18650 Li-Ion cell charger from BangGood, along with a flashlight and 18650 cell, as a present for my Dad who have wanted one of these T6 LED flashlight for some time now. I am now worried that this charger (which is meant to be plugged in directly into the mains) may be very dangerous. My dad travels around a lot in Sweden to inspect projects in the Swedish train rail system (I'm not very sure of the correct term), which means that this charger will a lot of times be directly besides his bed in the hotel room, and that means that it must be safe.

So basically, I would really appreciate it if a kind-hearted person here on this forum could tell me if I should just toss this charger and have him use my Intellicharger I4 from Nitecore and charge his cells instead (which I don't think will be way too big of a problem) or if this circuit is perfectly safe!












Link to this charger: http://www.banggood.com/Wholesale-New-Battery-18650-Travel-Charger-Wired-AC-Digital-Li-Ion-EU-p-28256.html

I really can't tell a lot from these photos as I'm not that "technical" yet, but I can really tell that there is not a lot of components in there, and the two mains wires look awfully thin! (Not to talk about the soldering, which I will sure redo if this charger is safe to use!

I appreciate every answer! Thanks a lot! 

[wraper]

My friend bought exactly the same on ebay. When it arrived, he asked what do I think about it. My answer was that he is idiot buing junk. Disassembled this sucker in front of him and showed that it could kill him easily. But he still uses it, think I was right about naming him idiot.

[wraper]

This explains it all.

[sleemanj]

See on wraper's image, the uppermost arrow, is that a bit of unetched copper almost bridging the mains voltage at one end of the rectifier to the positive terminal of the battery ?

[amyk]

My friend bought exactly the same on ebay. When it arrived, he asked what do I think about it. My answer was that he is idiot buing junk. Disassembled this sucker in front of him and showed that it could kill him easily. But he still uses it, think I was right about naming him idiot.

Your paranoia is astounding...

Unless your normal use case is holding the thing in your hand with your fingers across the terminals, there is basically nothing to worry about here. In fact I'd be more worried about it overcharging the cells than the absolutely miniscule risk of contacting the mains.

[wraper]

Unless your normal use case is holding the thing in your hand with your fingers across the terminals, there is basically nothing to worry about here. In fact I'd be more worried about it overcharging the cells than the absolutely miniscule risk of contacting the mains.

When you are holding the battery, there is already almost no or no at all insulation between you and exposed terminals. And I think it is not uncommon to touch the terminals too. About not properly charging, I said him about that too. Risk is not that minuscule, especially if you don't know if Chinese worker have not left some tiny solder blob somewhere. Even if there is no short for now, it is not excluded that it won't appear somewhere later (and there are a lot of places with small creepage) because of transient in the mains or something like that. If you ever unwinded those transformers, you'd have even less confidence in it. I've seen how wires of primary and secondary windings touch each other.

[mikeselectricstuff]

I also have a question regarding this small gap; I am fully aware that it's terrible design and that a very small mistake in the factory and this charger will blow up when you connect it to the mains, but if you actually would inspect that it does not bridge between somewhere it shouldn't be, is there actually a safety risk? Is there a risk that it will for some reason spark inbetween the small gap, or what can actually happen with a gap this small?

A mains transient can initiate a spark discharge across the gap. The spark current is not usually in itself dangerous, however the ionised air path provides a temporary low impedance path across the gap, which can both cause a dangerous current to flow, and cause burning and carbonisation of the PCB material, leaving a permanently conductive path across the gap. A carbonised PCB can present risks of both shock and fire.
 

[wraper]

BTW I do not have fear of electricity. However I do respect it. Have felt it on myself few tens of times I think. Without serious consequences though, as I never stick both hands somewhere if there is a risk.

[T3sl4co1l]

My friend bought exactly the same on ebay. When it arrived, he asked what do I think about it. My answer was that he is idiot buing junk. Disassembled this sucker in front of him and showed that it could kill him easily. But he still uses it, think I was right about naming him idiot.

Your paranoia is astounding...

It's not paranoia if the electrons are actually out to get you. Which they are.

Complete disclosure: I built an LED fixture which is live, exposed, ungrounded and un-isolated.  I did at least have the decency to hang the majority of the metal bits at a height beyond the range of "oops I fell against the fixture and electrocuted myself".  But I would NEVER allow it to be operated by or sold to anyone else!

Another way of putting it, for present case: if one day your friend comes home and the charger randomly doesn't work, it's probably been zapped.  Or if his house is burned to cinders...

Tim

[T3sl4co1l]

My dad had put in a RCD (I don't know if RCD is the right word, I got it from Translate) the day before, so I'm pretty sure that saved my life right?

Yikes, good thing!

RCD = Return Current Detector?  I forget what the preferred UK term is.  In the US it's GFI or GFCI (Ground Fault [Current/Circuit] Interrupter), the distinction between the two (if any) I'm not sure of.

[Yago]

Residual?

[Lightages]

The real danger here is if a spark did occur and cause the AC to flow into the battery without regulation, you would have a nice explosion and fire you could not put out. The garbage can was a good idea.

[Stonent]

These Nitecore ones are inexpensive chargers and seem to test well: http://budgetlightforum.com/node/14868
I'm planning on picking up one of the newer D2 models that have a display.  The D2 can do NiMH, NiCD, Li-Ion, and LiFePO4.

[TerraHertz]

Hmm. I have two of these (ebay 141522986807) in the post.  Au$7.21 each, free postage. Same as your pic.
They'll be running on 240VAC, rather than 110VAC. Double the fun.

The way I approach this, is I'll open them up on arrival and do any mods I think necessary for safety.
Also, they will be among other chargers on a common mains circuit that I turn off when not in use. Perhaps I'll add turning off the circuit while handing the adapters.  Also the entire place has RCD protection.

Yes, I'll accept some risk in return for very low cost.

[babysitter]

Don't you think the name is a hint good enough ?

[dave_j_fan]

get some exacto knife reduce track width , add extra copper wireon top if u like
  this after cheap charger wont help

[Yago]

Don't you think the name is a hint good enough ?

With some of those really dodgy TrustFire cells?

I simply bought a decent charger (Xtar VP1) and quality Panasonic cells.
Even so I won't use it unattended, and then in a "charge safe" flame proof bag.

Some friends mock me, call me "Captain Safety", it's a name I can live with

[mikeselectricstuff]

Those tracks are just an optional bypass for when the EMI filter is not fitted - not a safety issue.

...Unlike the completely screwed primary to secondary isolation, where they have a nice big gap and a slot under the optoisolator, but then a track to C7 crossing it  with minimal creepage distance

[wraper]

...Unlike the completely screwed primary to secondary isolation, where they have a nice big gap and a slot under the optoisolator, but then a track to C7 crossing it  with minimal creepage distance

And screwed safety in a completely stupid way. A little bit effort (or lack of stupidity) and it would be completely safe.

[wraper]

Hmm. I have two of these (ebay 141522986807) in the post.  Au$7.21 each, free postage. Same as your pic.
They'll be running on 240VAC, rather than 110VAC. Double the fun.

The way I approach this, is I'll open them up on arrival and do any mods I think necessary for safety.
Also, they will be among other chargers on a common mains circuit that I turn off when not in use. Perhaps I'll add turning off the circuit while handing the adapters.  Also the entire place has RCD protection.

Yes, I'll accept some risk in return for very low cost.

That's very expensive. My friend got it for $2.40 delivered.

[amyk]

Well I would be pretty worried if I knew that my battery charger would electrocute me if I "accidentally" touch one of the very exposed terminals while plugging the battery in, and at the same time maybe accidentally having contact with something grounded like a lamp or whatever. Also, I don't actually know what would happen, but I wouldn't want to plug in a lithium ion battery to the mains directly.

Maybe you where sarcastic and I didn't notice, sorry if that's the case!

No, I'm being completely serious. For you to be electrocuted, you would need to be simultaneously touching one of the terminals (the cutouts on the sides are there so you don't have to do so to remove cells from it), a good ground, and there would have to be a transient on the mains (that wasn't already absorbed by a MOV somewhere...) big enough to arc across the gap and pass enough current through you to kill. What's the probability of all those occurring at the same time? The risk has to be put into perspective. People do far, far riskier things, and the mortality rates are there to prove it. I hear of deaths in car accidents almost every day in the news, for example. On the other hand, it's quite likely that numerous chargers like this are in use without any problems.

With some of those really dodgy TrustFire cells?

UltraFire is the one to watch out for...

As for that AC adapter, I'm guessing they put the trace and provision for C7 there to stop EMI at the last moment, but realised that the SMD cap wouldn't withstand the voltage of a hi-pot test so didn't populate it. The risk of using that will be higher than the battery charger since it is usually plugged into a device you are in constant contact with, like a laptop.

[T3sl4co1l]

Is this the traces you mean? Sorry, I'm not very good at this stuff yet, I try to learn everything! And I hope that you understand my picture hahaha

Orange trace is from the big C7 capacitor, and the yellow trace is the one not isolated, I guess. The pink square is the minimal creepage distance.




I this what you meant?

Precisely.

Also, there's the isolation gap under the opto... but it's not wide enough to cover the proximity of traces. DUH

Noteworthy, there are no Y1 type capacitors on the line side.  So what little line filtering is present will be ineffective.  There is, at least, a tiny one across the barrier (C14 is it?), but it's returned to AC line rather than ground, so it had better be small, or you'll feel a tingle when you touch that output jack!

The filter would be more effective if there were a ground to work against.  Ah, but there is a ground: the power jack has a center pin!  They merely decided not to use it!

Tim

[arekm]

This explains it all.

AFAIK there are many different chargers that look exactly like this one. Different as with different electronics inside. Some are good, some are bad.

Here someone tested similar charger:
http://lygte-info.dk/review/Review%20Charger%20Heseny%20HXY-18650-2A%20UK.html
and "Testing with 2500 volt and 5000 volt between mains and low volt side, did not show any safety problems."
but it could contains different PCB.

Anyway better buying something like:
http://www.banggood.com/XTAR-MC2-18650-14500-26650-Battery-Micro-USB-Smart-Charger-p-954097.html
or
http://www.banggood.com/XTAR-VC2-Charger-With-LCD-Screen-Display-For-18650-26650-Battery-p-954348.html
or (not that cheap but very nice):
http://www.banggood.com/Powerfocus-BC3100-Ni-Mh-lithium-ion-Battery-Charger-With-Charger-Line-p-921306.html

[wraper]

Here someone tested similar charger:
http://lygte-info.dk/review/Review%20Charger%20Heseny%20HXY-18650-2A%20UK.html
and "Testing with 2500 volt and 5000 volt between mains and low volt side, did not show any safety problems."
but it could contains different PCB.

1mm or thereabouts creepage covered with solder mask probably will withstand 5kV for some time. Question is for how long time, if air is dry or wet, if you are lucky with your particular unit.

[TerraHertz]

That's very expensive. My friend got it for $2.40 delivered.

In Latvia?

$7.21!? For that price you can almost get a charger which wont catch fire or electrocute someone! 

Links please. To one with an Au mains plug & free ship to Australia.
It's true I didn't spend hours searching. Only about 10 minutes. It was annoying to wade through all the ones with US plugs.
Also the $7.21 each is in $Au, which is US$5.93 at the moment.