Cheap BangGood 18650 charger, is it really safe? - Page 1
Forum section: electronics / projects

author: patrikcarlsson
author_rank: Newbie
timestamp: January 16, 2015, 10:41:20 pm
content: 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-0KfEAlso, 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.htmlI 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!

author: wraper
author_rank: Unknown
timestamp: January 16, 2015, 11:06:17 pm
content: 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.

author: wraper
author_rank: Unknown
timestamp: January 16, 2015, 11:13:58 pm
content: This explains it all.

author: sleemanj
author_rank: Super Contributor
timestamp: January 16, 2015, 11:18:33 pm
content: 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 ?

author: amyk
author_rank: Super Contributor
timestamp: January 16, 2015, 11:31:31 pm
content: Quote from: wraper on January 16, 2015, 11:06:17 pmYour 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 absolutelyminisculerisk of contacting the mains.

author: wraper
author_rank: Unknown
timestamp: January 16, 2015, 11:44:00 pm
content: Quote from: amyk on January 16, 2015, 11:31:31 pmWhen 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.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 16, 2015, 11:49:10 pm
content: Quote from: patrikcarlsson on January 16, 2015, 11:27:42 pmA 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.

author: wraper
author_rank: Unknown
timestamp: January 16, 2015, 11:49:37 pm
content: 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.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 17, 2015, 12:42:34 am
content: Quote from: amyk on January 16, 2015, 11:31:31 pmIt'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

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 17, 2015, 12:44:57 am
content: Quote from: patrikcarlsson on January 17, 2015, 12:01:12 amYikes, 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.

author: Yago
author_rank: Frequent Contributor
timestamp: January 17, 2015, 12:54:13 am
content: Residual?

author: Lightages
author_rank: Unknown
timestamp: January 17, 2015, 01:04:21 am
content: 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.

author: Stonent
author_rank: Super Contributor
timestamp: January 17, 2015, 05:50:54 am
content: These Nitecore ones are inexpensive chargers and seem to test well:http://budgetlightforum.com/node/14868I'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.

author: TerraHertz
author_rank: Super Contributor
timestamp: January 17, 2015, 07:42:21 am
content: 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.

author: babysitter
author_rank: Frequent Contributor
timestamp: January 17, 2015, 08:07:17 am
content: Don't you think the name is a hint good enough ?

author: dave_j_fan
author_rank: Regular Contributor
timestamp: January 17, 2015, 10:13:23 am
content: get some exacto knife reduce track width , add extra copper wireon top if u likethis after cheap charger wont help

author: Yago
author_rank: Frequent Contributor
timestamp: January 17, 2015, 11:27:20 am
content: Quote from: babysitter on January 17, 2015, 08:07:17 amWith 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 canlivewith

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 17, 2015, 01:08:31 pm
content: 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

author: wraper
author_rank: Unknown
timestamp: January 17, 2015, 01:31:43 pm
content: QuoteAnd screwed safety in a completely stupid way. A little bit effort (or lack of stupidity) and it would be completely safe.

author: wraper
author_rank: Unknown
timestamp: January 17, 2015, 01:37:25 pm
content: Quote from: TerraHertz on January 17, 2015, 07:42:21 amThat's very expensive. My friend got it for $2.40 delivered.

author: amyk
author_rank: Super Contributor
timestamp: January 17, 2015, 04:24:44 pm
content: Quote from: patrikcarlsson on January 16, 2015, 11:40:35 pmNo, I'm being completely serious. For you to beelectrocuted, 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,andthere would have to be a transient on the mains (thatwasn'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,farriskier 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.QuoteUltraFire 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.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 17, 2015, 04:31:13 pm
content: Quote from: patrikcarlsson on January 17, 2015, 01:31:27 pmPrecisely.Also, there's the isolation gap under the opto... but it's not wide enough to cover the proximity of traces. DUHNoteworthy, 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

author: arekm
author_rank: Unknown
timestamp: January 17, 2015, 11:19:42 pm
content: Quote from: wraper on January 16, 2015, 11:13:58 pmAFAIK 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.htmland "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.htmlorhttp://www.banggood.com/XTAR-VC2-Charger-With-LCD-Screen-Display-For-18650-26650-Battery-p-954348.htmlor (not that cheap but very nice):http://www.banggood.com/Powerfocus-BC3100-Ni-Mh-lithium-ion-Battery-Charger-With-Charger-Line-p-921306.html

author: wraper
author_rank: Unknown
timestamp: January 17, 2015, 11:49:40 pm
content: Quote from: arekm on January 17, 2015, 11:19:42 pm1mm 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.

author: TerraHertz
author_rank: Super Contributor
timestamp: January 18, 2015, 03:11:35 am
content: Quote from: wraper on January 17, 2015, 01:37:25 pmIn Latvia?Quote from: patrikcarlsson on January 17, 2015, 01:40:09 pmLinks 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.

author: TerraHertz
author_rank: Super Contributor
timestamp: January 20, 2015, 02:02:36 am
content: The two I ordered arrived. They are different inside to the others shown in this thread (no surprise.)Initial pics below.The two ICs are TL431A, a programmable shunt regulator.I haven't traced the circuit yet.PCB creepage clearance seems OK to me, BUT who knows what the isolation is like in that tiny transformer.Just on first impression, I'd bet the charge current will be quite low. The case gets only slightly warm on charge.Ha ha, spot the mains 'fuse'.More later.

author: coppice
author_rank: Super Contributor
timestamp: January 20, 2015, 02:26:38 am
content: Quote from: TerraHertz on January 18, 2015, 03:11:35 amYou say "with Au mains plug" like its rare case. Since the Australian plug is also the Chinese plug, its the one the Chinese make in the largest volume.

author: wraper
author_rank: Unknown
timestamp: January 20, 2015, 03:01:27 am
content: Quote from: TerraHertz on January 20, 2015, 02:02:36 amJust PCB track and a place for optional real fuse. Though that track seems to be too wide to give any real protection.

author: rickselectricalprojects
author_rank: Regular Contributor
timestamp: January 30, 2015, 11:17:39 am
content: if its from a website called banggood its probably not safe

author: HKJ
author_rank: Super Contributor
timestamp: January 30, 2015, 12:25:32 pm
content: Quote from: TerraHertz on January 20, 2015, 02:02:36 amI believe that the creepage distance looks low for 230VAC equipment, but it probably fine for 120VAC.

author: Alex30
author_rank: Regular Contributor
timestamp: January 30, 2015, 12:51:46 pm
content: While we're on the topic of creepage , I was wondering if any ee knew the standard for 240VAC creepage distance? Or at least the typical manufacturing standard?

author: tattarn
author_rank: Newbie
timestamp: January 30, 2015, 06:47:51 pm
content: EN60950 if you are working with information equipment.

author: Alex30
author_rank: Regular Contributor
timestamp: January 31, 2015, 03:00:07 am
content: Quote from: tattarn on January 30, 2015, 06:47:51 pmThanks for the reply but I don't want to spend loads of money just to answer my question. I'm not looking for a reference document, i'm just wondering what the usual practice is for practical engineering of common appliances.

author: wraper
author_rank: Unknown
timestamp: January 31, 2015, 03:27:18 am
content: Quote from: Alex30 on January 31, 2015, 03:00:07 amLOL, google non existent for not being able to type there EN60950 and creepage? Usual good practice or usual crap practice? One will say one figure, another different one. Will determine who is right by post count?

author: wraper
author_rank: Unknown
timestamp: January 31, 2015, 03:47:46 am
content: BTW it is different figure for different conditions. Simplest of them - is device grounded or double insulated.

author: Alex30
author_rank: Regular Contributor
timestamp: January 31, 2015, 04:21:17 am
content: Quote from: wraper on January 31, 2015, 03:27:18 amDidn't try those terms I just looked for thedocument. Also why is it that when I ask for a general answer to a question where I know there is no exact answer on this forum, I get smart alec replies? I want to know the usual crap practice what do you think

author: wraper
author_rank: Unknown
timestamp: January 31, 2015, 05:31:21 pm
content: http://www.ieee.li/pdf/essay/safety_considerations_in_power_supply_design.pdfIMO this document describes subject quiet well.

author: wraper
author_rank: Unknown
timestamp: January 31, 2015, 05:46:56 pm
content: Quote from: Alex30 on January 31, 2015, 04:21:17 amYou got such reply only because of your own attitude in the previous post.

author: Mr Simpleton
author_rank: Unknown
timestamp: January 31, 2015, 06:59:18 pm
content: I guess we do get what we pay forhttps://www.eevblog.com/forum/reviews/batter-charger-18650-do-not-turn-it-on-take-it-apart!/

author: HKJ
author_rank: Super Contributor
timestamp: January 31, 2015, 07:43:21 pm
content: Quote from: Mr Simpleton on January 31, 2015, 06:59:18 pmThe really cheap charges are not worth getting, but you can get good chargers below $20.Last year I tested and reviewed about 45 chargers (My reviews are on the technical side) and there where both good and bad charger in that lot.