Is this possible?

Hozer

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As most of us know the "BMS" in not a fuse it regulates the voltage and amperage. The first thing that goes bad on a EBIKE battery is the BMS. Is it possible to put a fuse on the BMS to prevent overcharging of the battery to help prevent a battery from catching fire?
 
A proper charger handles all of the risks you are concerned about (excessive charging current, excessive charging voltage).
Most battery fires are caused by one of three things.

1. Very low-grade Chinese cells in the battery, which have a high failure/short rate.

2. Battery packs being used to deliver more current than they are rated to deliver, seen on very high powered eBikes/scooter/e-motorcycles.

3. Excessive charging current. This is most frequently seen with big-city courier services (New York, London), where they are using a higher current charger to "speed up" the process of charging the batteries. This allows them to do more money-making runs each day.
 
Ok but there has to be a better way to keep your battery safe. Maybe some type device that can go in between the charger and battery to make sure the charger is working correctly. Just an idea.
 
Ok but there has to be a better way to keep your battery safe. Maybe some type device that can go in between the charger and battery to make sure the charger is working correctly. Just an idea.
If you don’t trust your charger or your BSM you *could* put a voltmeter and an ammeter in line to monitor what is happening. This would presume you had the training and education to interpret the results. Failing that you’re pretty much stuck trusting your charger.
They do make smart chargers with the capability of doing really smart things like charging to 80% and then going in to maintenance mode. Be prepared to spend anywhere from $300 to $1500.
 
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You could add a good quality "programmable overcurrent protection switch" (see amazon.com - about $20), but that means fiddling with the cables, which must be done properly. Moreover, I would buy a good quality one (no cheap Alibaba stuff or so), otherwise you add risk to risk.

As for the problem of avoiding overcharging, here is what I do:

1) discharge the battery once (to 5-10%), then monitor the charge every 15-30 minutes to make a "time vs. charge %" graph.
2) buy a remote switch ($10 or so). I use a TP-LINK Tapo P100.
3) Connect it to an app like SmartThings that allows you to easily turn it off automatically after a certain time interval. So I can turn it ON whenever I like, and then program the switch to turn off the charger when the battery is at 80% according to the graph in (1).

It looks a bit complicated, but it works well and doesn't cost too much. And after some time you know more or less by memory how much time you need. And it works even when you are not at home.
 
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