Hello, I currently have an Arduino Uno that controls a motor through an H-Bridge circuit. The motor is powered by 2 lipo batteries connected in series.I know that lipo batteries shouldn't be discharged beyond 3V and was wondering how I could prevent this.
I have been told I can use a 6V relay, I was wondering if that is the best option and if I need to take into account any other considerations. I would appreciate any help or advice.
Thanks!
Hi, Since you/your Arduino has control of the motor, it would be best to measure the cell voltage(s) with Arduino, and make your own decisions, discharge warnings, shutdowns etc.,.
If you use a 2:1 voltage divider like two 100K resistors in series, you could measure the 7.2V point, and you could measure the 3.7V point directly, on two separate Analog inputs.
Subtract bottom Cell from total to get top cell??
Thanks Terry King!
Measuring the voltage with the Uno hadn't occurred to me. I will have a go at doing that the first chance I get!
I did exactly what Terry suggested in my radio-controlled car project:
Worked fine, and then you add in code to shut down the motors so you don't draw any more when the battery is low. Plus you could always flash an LED to warn the user.
I'd use a ~10k series resistor for the 3.7V point, not a direct connection because we are dealing with LiPoly batteries here. Accidental shorts with a LiPoly are very bad news indeed, enough current capacity to vaporise wiring if something goes wrong.
Isn't it already going through a 10K resistor? Those two resistors are near the Arduino pin, not near the battery.