Whats the proper way to wire a Li-ion rechargeable battery?

I have a Li-ion battery that I want to use to power mini portable speakers. I want to enclose the battery into the portable speaker's box and have a port drilled into it to recharge the battery. So what is the proper way of doing this? The Positive + and negative - of the battery is connected to the speakers right now, so would I just cut into the positive and negative and add my charging port? (I have the correct charger for the battery by the way) Hopefully I explained this well enough for someone to help, thank you!!

frollard3 years ago
You need protection from the following scenarios:

Reverse polarity input
Maximum charge input current
Maximum charge input voltage
Maximum battery charge voltage level - overcharge lithium = fire
Battery temperature monitoring (optional)

Short circuit/overcurrent output (will cause battery to start on fire)
Battery discharge level - overdrained lithium = permanent damage.

Products like that take the usb input and outputs the correct amount of voltage for the correct amount of time on a single cel lithium cell.
Zebrah (author)  frollard3 years ago
Thanks for the response! The battery has a built in protection circuit and the wall charger portion detects when the battery is at its full voltage and cuts off as well. As for adding a charging port I am still a little concerned about. Since they have the proper protection for the battery and the proper wall charger. Is adding a port to charge the battery just as simple as cutting and adding it into the positive and negative leads coming off the battery? (Which also go to the portable speakers)
Well the answer depends on your exact battery and charger. If you only have one "battery" then yes with a caveat I will discuss below. If the positive and negative of the battery is what you would hook up to your charger normally then you are just essentially making and extension cable to the device from the charger.

However if you wire the charger straight to the battery/speakers you need to make sure the speakers have a rating above the output of the charger. So if the charger ouput is 4.2V as most 3.7V li-ion chargers are then make sure this wont hurt the speakers. The easiest/best solution is to use a spst switch to isolate the battery from the rest of the circuit while charging. This will prevent any headache with incompatible voltages and prevent drawing to much current from the charger.
I've got a similar question. I am thinking of making a moped (ebike) by using a li-ion battery wired to a motor, if the motor turns without the battery turning it (thus generating electricity) would it overload the battery, or just recharge it?