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SAFETY ADVISORY: Faulty charger may lead to risk of 16X battery fire

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1 hour ago, RetroThruster said:

Mine did the same thing, I had it set to stop at 80% but when I checked WheelLog it stated that it was at 92%, at this point, I stopped charging, I'm a little fuzzy on what the charger was reading at at that time but it seems like it was just barely over 80% but had stayed there for quite some time, I wonder if it's a combination of the charger charging at 88v and the BMS not recognizing the issue and stopping it AND the charger not stopping at the selected percentage, if at all.  

I completely agree.

Although the charger outputs at a constant voltage (the “size” of the electron pipe, which should remain at 84.2V and can be see on the charger readout when the charger is on but not yet plugged into the EUC), it does vary the amperage (the rate of “flow” of electrons inside the pipe) depending on the current output voltage of the batteries.  The EUC's BMS controls the output voltage of the batteries, and thus “controls" the output amperage of the charger.

This leads us to postulate that there are two probable reasons a fire like this could have occurred:

1. The BMS had a fault in output voltage and thus incorrectly "communicated" to the charger that the batteries achieved full capacity, and thus allowed the charger to overcharge the pack and cause the battery damage that could lead to a fire.

2. The charger either had a fault or for some other reason did not lower its output amperage when the batteries reached their maximum voltage threshold, thus overcharging the batteries and leading to the battery damage and fire.

In my opinion, and based on my and @RetroThruster's observations, the problem appears to be #2, as the charger when plugged into a 16X does not automatically shut-off when the charger is set to 80% and the 16X's battery pack then reaches 80% capacity, and thus it is likely it also does not lower it's output amperage when it reaches 100% either.  In the case of the user who experienced the fire, if his charger kept charging after the battery reached 100% rated capacity, the output voltage of the battery (not the charger) would then exceed the rated voltage of 84.2V, which would readout on the charger (the 88V the user saw), and cause the damage and subsequent fire.

My 2-pence…

Edited by JZT-Colorado

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3 minutes ago, Seba said:

Pro tip for every EUC owner: buy a decent multimeter.

Just some info what "decent" could mean:

 

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3 hours ago, Seba said:

Don't look at the percents. They differ from app to app and are only very rough information about battery charge. Always look at the battery voltage! Voltage is the key parameter that will let you know of battery state of charge. When your battery voltage is 84 V it's near to full charge. If battery voltage goes above 84.5 V you should immediately disconnect your charger and inspect its output voltage with precise multimeter. Why? Because even voltage measurement made by wheel mainboard may be off. So wheel may read battery voltage as 84.5 V but real voltage will be just 83.9 V.

Pro tip for every EUC owner: buy a decent multimeter. It's a very valuable tool for inspecting and checking your electrical things. I think having decent multimeter and basic knowledge how to use it is a good thing. Multimeter is far more versatile than Charge Doctor or any other tool. You can inspect wiring, check resistance/shorts/open circuits, measure currents, voltages, temperature etc.

I learn something new every day here, I really appreciate that and will keep an eye on the voltage as well!

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14 hours ago, Chriull said:

- Charger output and mainboard is behaving fine, but some cells are dead. I have no idea how this will behave?

The two occasions when cells died on my 16S, both times the BMS succesfully interrupted every single charging event once the 15 healthy pairs had reached the overvoltage limit, which was about 63.0V for the 67.2V wheel.

 

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4 hours ago, mrelwood said:

The two occasions when cells died on my 16S, both times the BMS succesfully interrupted every single charging event once the 15 healthy pairs had reached the overvoltage limit, which was about 63.0V for the 67.2V wheel.

Yes! Should be some CC up until the first cell reaches cut-off threshold - should be easily detectable to warn the user.

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3 hours ago, esaj said:

... if I'm wrong, somebody please do correct me, always happy to learn. ;)

...

Me too!  🙂

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On ‎10‎/‎16‎/‎2019 at 4:31 PM, Jason McNeil said:

 or the voltage exceeded the BMS MOSFETs max voltage, this may have blown with the gate open,

....making it a completely pointless overvoltage safety feature. Mechanical or solid state fuses could easily deal with this, maybe also run an RCD while you're at it. Anything to deal with an unusual voltage situation. At no point should this issue have to cause damage to the BMS or, god forbid, the battery. There are more than enough electrical solutions to prevent an input overvoltage causing damage to other components.

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Update from an email that I received  from eWheels.  Basically it looks like the charger was exposed to rain and water causing it to fail. 

Good afternoon, 
 
I have just received the lab results back for the defective charger investigation: the conclusion that the Engineers reached, was that because the charger used on a boat & exposed to rain/wash, component corrosion deterioration built up, resulting in this over-charge situation (full lab results attached).
 
The charger's circuit-board is elevated to offer some primary protection against water, but is not designed to be left in an outdoor environment. 
 
Conclusion:   
It ought to be safe to continue using the charger. Prior to use, please always check the display that the voltage is showing ~84v, after pressing the reset button, but before plugging into the Wheel. If the voltage is elevated beyond 84.5v, NOT USE the charger & let use know immediately; keep the charger in a dry environment.   
 
Thank you & have a good day,
 
Jason 

 

 

Edited by EvoKnvl

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2 hours ago, EvoKnvl said:

The charger's circuit-board is elevated to offer some primary protection against water, but is not designed to be left in an outdoor environment. 

Good to know :o, then I don't take my 16X into the bathtub anymore while it's just being charged. But luckily nothing has happened to me yet. :efefc8626c:

:roflmao:

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