Hello everybody, i m looking for a “simple” way to turned off a LIPO battery (with a relay for exemple) when it reached a certain voltage.
Could you help me ?
Best
Hi,
Do you need a full cut-off for the battery, or only a cut-off of a large load, like a motor?
Some circuits are available that can be used with a motor controller to cut-off the motor when the voltage of the LiPo drops too low. However, these circuits only cut-off the motor, and the motor controller and the LiPo cut-off circuit itself still remain powered. The idea is that the circuits consume a small amount of current compared to the motor, and that you’ll notice the motor has turned off and will unplug the battery (ex: to charge it) not too long after that.
Is this what you are looking for, or do you need something that will cut-off the LiPo entirely so that you can leave the circuits connected for hours/days without needing to disconnect the battery? If you’re looking for the later case, then you might need to build a custom circuit depending on your needs…
Hope this helps,
Thanks, i need something that will entier my cut off a 4S lipo. What kind of custom circuit should i make ?
Best
Ok, in that case we would recommend using a microcontroller with an analog input to measure the battery voltage (using a 1/4 voltage divider to bring the max voltage below 5V), and the microcontroller can control the relay which will be normally-open. Something like an Arduino or PICAXE will work for that.
Since the relay will be turning off the power to the microcontroller at the same time, you will need a momentary switch in parallel with the relay to give the initial power to the microcontroller that will in turn be able to activate the relay.
What kind of load will you be placing on the batteries? Will it be some small electronics with a low and relatively-constant current consumption or does it include motors that can have large in-rush currents?
Depending on what’s the load, you may need to calibrate the algorithm in the microcontroller to ensure that it doesn’t cut-off the relay during short brown-out situations. This is important since if it’s poorly calibrated, the relay could open, turning off the microcontroller, and then your system won’t recover from this problem…
We hope this helps,