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 .