Reading LiPo battery voltage but instead setting on fire.

Hi Everyone,

I've recently set up an Arduino uno to detect when a LiPo battery (6000mAh 7.4V 60C) gets to a low voltage (3.2V per cell) then uses a relay controlled by the digital output pins via a transistor circuit to turn the battery off. I have tested my programming using a power supply and confirmed that it does work correctly then tried to test it with the batteries.

I hadn't even turned the Arduino on as i plugged the 3 pin molex connector from the battery into the board to read the voltages through the analogue pins when the wires i was holding became ridiculously hot and the Arduino began smoking and getting seriously hot.

Has anyone else experienced this? Is my Arduino faulty? I've seen plenty of people using Arduinos as a low voltage battery cutoff and not had this happen. When fully charged the cell is only 4.2V so doesn't go over the 5V input either, just sets itself on fire.

Thanks.

Clearly a short circuit happened. Did you check for shorts with a meter beforehand? Its always wise to
do this.

There are probably reasons for the fire in the circuit diagram, that you have not posted, of how you have it all connected.

A 60C 6Ahr LiPo is capable of probably 500A under short conditions, its why great care and fuses are needed in circuits.

EEW:
I hadn't even turned the Arduino on as i plugged the 3 pin molex connector from the battery into the board to read the voltages through the analogue pins when the wires i was holding became ridiculously hot and the Arduino began smoking and getting seriously hot.

If you connected the 7.4v or any Lipo battery directly to the arduino ADC pins you are wrong...

You are running 7.4v to a pin which most likely burnt and shorted a pin and then it went full current which is a fire hazard. You should be using voltage dividers to the ADC to keep the max voltage under VCC and reducing the amount of current that can flow through the sensor.

Hi,
Welcome to the forum.

Please read the first post in any forum entitled how to use this forum.
http://forum.arduino.cc/index.php/topic,148850.0.html .

Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?

Can you post a picture of your burnt project please?

Thanks..Tom... :slight_smile: