Dear all,
I recently bought five Li-ion 18650 batteries (http://www.thrunite.com/thrunite-18650-battery-3400mah-2/)
My idea was to power a 18V DC motor, so I simply connected the 5 batteries in series (5x4.2V=21V) without any additional circuitry.
The issue is the following: If I connect the motor to a workbench power supply, everything works (current consumption ~3A)
If I connect my Li-ion pack, the motor does not move at all and the batteries just get hot (one in particular VERY hot)
Afterwards, I checked if the batteries got damaged. The individual voltage of the batteries was 4.1V and the voltage of the pack was 20.5V. I then removed the battery from the pack and I recharged each battery individually. All the batteries seem to be ok.
I'm still puzzled why I was not able to power the motor. The description of the battery says that an overcharge/discharge protection circuit is integrated in each battery, but I was not able to find any datasheet about it. Maybe protected Li-ion batteries cannot be put in series? Or I am missing something else?
I recently bought five Li-ion 18650 batteries (http://www.thrunite.com/thrunite-18650-battery-3400mah-2/)
My idea was to power a 18V DC motor, so I simply connected the 5 batteries in series (5x4.2V=21V) without any additional circuitry.
The issue is the following: If I connect the motor to a workbench power supply, everything works (current consumption ~3A)
If I connect my Li-ion pack, the motor does not move at all and the batteries just get hot (one in particular VERY hot)
Afterwards, I checked if the batteries got damaged. The individual voltage of the batteries was 4.1V and the voltage of the pack was 20.5V. I then removed the battery from the pack and I recharged each battery individually. All the batteries seem to be ok.
I'm still puzzled why I was not able to power the motor. The description of the battery says that an overcharge/discharge protection circuit is integrated in each battery, but I was not able to find any datasheet about it. Maybe protected Li-ion batteries cannot be put in series? Or I am missing something else?