What makes these cheap Chinese chargers so dangerous?

[MarkJohnston]

I've been using these Ali express Tang powers chargers for a long. I originally bought 3x of the more powerful 3amp, but they all crapped out without any physical indication of any electrical shorts. I would oscilloscope to see the damage or a microscope, not sure which one is used here. In any case I kept trying on my quest to buy a bunch of cheap chargers. I've been using an even cheaper tangs power charger than these and I've already done 1000 chargers on it. I use my bike for transportation (anti car for enviromental and other reasons) so you guys can believe me when I say I've done 1000 charges. You guys have told me not use the chargers because another member on here had a big fire or something but I've yet to see anything. All that really happens is the fuses blow out. And I have a large junk pile of these so I keep ripping out fuses and soldering them in. (I've only had to do it twice so far, knock on wood. )

Anyways I included some pictures of the charger. Obviously I ripped it out of the casing because this one was a Dud and couldn't figure out how to get it to work again. I've had better luck with their 1AMP chargers which are even cheaper at $10 a pop. This is one of the higher amp ones that broke. Don;t think I am charging like this, but with me you never know

I am also not sure if my battery has a BMS with a charging circuit. I know it has a balancing one. I would also like to know how to determine if a BMS has a balancing circuit. I do see the positive and negative of the battery ran to the BMS but it's hard for to tell if that's normal. Perhaps my battery is very well made. It does have cell holders and it's a very well done job by the looks of it. The cells are so so. But good enough. I am not sure if perhaps my battery has saved me from the worst of it.

Will ya guys look at these pictures and tell me why the design is unsafe? I am about to buy another cheap charger for a much smaller battery I built. It seems like they are highly unlikely to be dangerous just prone to burning themselves out.

 

[99t4]

In my experience, they have weak cooling fan bearings/bushings that squeal and wheeze and soon fail, causing the rest to overheat.

 

[MarkJohnston]

In my experience, they have weak cooling fan bearings/bushings that squeal and wheeze and soon fail, causing the rest to overheat.

Interesting. I don't know much about electronics. I am studying to be a programmer right now instead just because I don't have time or money for a MEE. I am using a little bit more expensive $40 charger off ALI express. I did have to modify the charger a bit for it to work. It was set at WAY too high of a voltage even though I ordered it for a 48 volt battery.

Interesting the cheaper chargers from tang don't have fans but they only charge at 1A. Honestly not really a different between the $40 3A charger and the tangs. The tangs for some reason blow fuses or diodes or whatever after a lot of charges.

 

[tomjasz]

It was set at WAY too high of a voltage even though I ordered it for a 48 volt battery.

odd, mind sharing the peak voltage of the charger!

 

[offGridDownUnder]

It seems like they are highly unlikely to be dangerous just prone to burning themselves out.

Are the reports you mention about fires caused by the charger, or by fires caused by a battery that has been abused by the charger?

The latter is quite realistic.

 

[whatever]

they do look very low cost layout, I would check some components, if there is mosfet or similar, anything with a heatsink, test it, they might just be cheap chinese components, put in some oem and might be robust, if its deisgn flaw then nothing will help.

 

[MarkJohnston]

odd, mind sharing the peak voltage of the charger!

It was suppose to be 54.6. It's even written on the case. It was at 54.9. I trimmed it down though, there was a trim pot inside. Kind of a cool design how the top cover slips off. YEah the better(more expensive) charger has two Fets, and removable fuse too.

Pretty sure the crappy chargers still have constant current and constant voltage. They also charge at 54.9 even though I asked for 54.6 peak.

I will not buy one of these crappy chargers again, Now that I found good crimps that work really good with my cheap crimper, and also figured out the voltage issue. That case really tripped me out the way it opens, I thought I was gonna need slim small fingers to reach inside there with live voltage.

huh.... I wonder how long it takes to mess up the battery? It's been about two years of charging with them about every day.

 

[Hummina Shadeeba]

.3v is not much at all. Dispersed over 14 cells …. 0.02v each cell. Insignificant.

Touching the inside of the charger with live voltage sounds dangerous though.

 

[tomjasz]

It was suppose to be 54.6. It's even written on the case. It was at 54.9. I trimmed it down though, there was a trim pot inside. Kind of a cool design how the top cover slips off. YEah the better(more expensive) charger has two Fets, and removable fuse too.

Pretty sure the crappy chargers still have constant current and constant voltage. They also charge at 54.9 even though I asked for 54.6 peak.

I will not buy one of these crappy chargers again, Now that I found good crimps that work really good with my cheap crimper, and also figured out the voltage issue. That case really tripped me out the way it opens, I thought I was gonna need slim small fingers to reach inside there with live voltage.

huh.... I wonder how long it takes to mess up the battery? It's been about two years of charging with them about every day.

I have two Satiators but also have a few $10 fanless that get used fairly frequently when I'm riding daily. I used some epoxy thermal glue to add cooling fins to the fanless. In warmer weather, I adapted a computer fan and power supply to move the air through the fins. No problems

 

[Sturmey]

.3v is not much at all. Dispersed over 14 cells …. 0.02v each cell. Insignificant.

If I may add to what you said, most/many multimeters anyhow are only specified/guareenteed as accurate at best to about 1% plus one least significant digit. I think you would need a more accurate lab type instrument/meter or calibration reference voltage to measure more accurate than this .

 

[MarkJohnston]

Yeah these keep blowing. I guess they are thermal resistors? You can see where the circuit board got super hot.

 

[richj8990]

I've bought two Chinese Hailong II batteries on Amazon, that both had good reviews (a good idea to look at the reviews!). First was $329, second was $459. First only lasted about 225 cycles because I ignorantly charged it at only 50% empty. Second has a bit under 100 cycles on it and no range loss at all so far. Neither has started a fire or charred anything around it. Yes the AC adapter can get hot for maybe an hour or so at the beginning of the recharge and then it cools down. Otherwise they are 100% fine and reliable. Don't buy dangerous stuff on Ali Express. And don't take any Tik Tok challenges

 

[MarkJohnston]

Yeah, I'm not buying anymore of these tangs power chargers.

 

[m3vuv]

I had one greeway 18s charger that was setup wrong and made my pack set on fire,,i rebuilt a 13s pack and adjusted the charger voltage to 54.6,its been ok since,seems mostly down to no qc,typical china made.

 

[ganzey]

only lasted about 225 cycles because I ignorantly charged it at only 50% empty.

Charging at 50% will absolutely, 100%, NEVER cause any damage whatsoever to a lithium battery. You Got a junk battery. The ones sold on amazon are the exact same as the ones sold on Aliexpress, just more expensive because someone is buying them and storing them over here for faster shipping. Also, it is not normal for an AC adapter to get hot.

 

[Hummina Shadeeba]

What does charging at 50% empty mean? If the battery got down to 50% of 4.2v, so 2.1v, that will damage it and if u were to then charge at a high current I think could be dangerous.



What’s a reliable and hopefully quiet 120-126v supply/charger?

 

[Jackal21]

One question for those that know electronics and how inteligent chargers work:
During the ballancing charging process, what are the situations that a charger can cause a battery fire? What has to happen inside it to cause that?
Let's say we are there to stop overcharging it if the charger fails to so we can remove this one from the list. What can be other scenarios, that we can't stop even if we're there?

In my case it's an ISDT T8 1000w 8s charger, and three 8s8p (30v 32Ah) charged in parallel so 30v and 32x3=96Ah. Out of Samsung INR T3 21700 4000mAh new cells.

 

[rafalg]

The typical cause of battery fire is a short circuit, which shouldn't happen during charging. But there are some videos (one at least) suggesting that a seriously overcharged cell may ignite.

But this video shows that they really abused this cell, it was charged to 4.7V at 5.15 amps. Maybe same thing could happen during normal charging, but very unlikely. The battery whould have to be bad already, some cells dead or almost dead.

 

[Jackal21]

Thanks for the fast reply!
I realy want to have an ideea of the risk scenarios that can take place in the apartment.

1. Storage/when is not in use or charged.
I presume that a well treated, undamaged, out of branded cells pack, can't be dangerous while just standing at storage voltage, right?

2. The overcharging.
This we can exclude if we monitor the charging process. Corect?

3. The short circuit.
This you said it shouldn't happen. Why do you think that?
And can the insides of a charger sustain a short of an 30v 96Ah battery that would, otherwise evaporate almost any heavy duty connector in the event of a short, mantain it that long that the pack heats up to runaway?

Did I left out other scenarios?

 

[rafalg]

You can't exclude overcharging - if we can assume a charger can break and develop a short circuit, then also some bad things can happen to BMS, protection circuit etc. But i wouldn't be that worried about short circuit in the charger - there are pretty thin wires and pretty flimsy connectors, they would burn first before the cells have a chance to ignite.
All in all, a single 18650 cell is really safe, you can store it for years, charge, discharge, even abuse a little - it won't explode. Only if you make a hole in the casing fire may start. But if you connect a hundred of them in a big battery then things can go out of control quickly - short circuit results in much larger currents and fire can develop fast. But not very likely that it suddenly develops a short circuit when just sitting unused on the shelf.

 

[Jackal21]

I don't use a bms, only balance charging.
"You can't exclude overcharging" If I know how much time the charging takes and I'm there and see on the charger screen when it reaches the 4.15v/cell that I've set, and I turn it off in case it doesn't by itself because the charger went bad, how can overcharging take place then?

 

[rafalg]

If you have a charger with voltage monitoring then it's allright, i thought about simple case when you charge the battery with just a dumb charger, and rely on internal battery circuitry to protect it. Then, when something breaks and some cells overcharge, you wouldn't be aware of that.

 

[Jackal21]

So, in conclusion, We have excluded from the danger list:
- Storage, if the cells are in good condition (branded, no damage, same voltage, same age etc)
- Overcharging, if we have an inteligent charger, displying the cells voltages and resistance, overall voltage, and if we are monitoring it, especialy at the end of the process.
- Short circuit, because at the power of big packs not much in the charger will keep the short long enough to overheat the cells.
And now we can be like that husband who said to his wife:
- I bet you can't tell me something that will make me happy and sad at the same time.
Wife: You have the biggest dic..of all youre friends!
Now we can be happy that logical situations can be avoided through care, but concerned that karma is not one of them..
Thanks for the responses.