Checking voltage on my LiPo battery


I’m trying to build a quadcopter based on Gadgeteer (yes, yes, I know, it’s hard, almost impossible, we’re talking interpreter here, the speeds are low, yada yada yada),
There are several voltage checkers in the market that buzz when dropping below 3 or 2 vols (like this one, but there are many others).
I am interested in such a voltage checker that can talk to the Hydra.


Connect your battery voltage to resistor divider (2 resistors) to scale the voltage below 3.3V then use any of the analog inputs.

That should do it.


Keep in mind that LiPo’s keep the voltage quite constant over time, so I don’t think it’s a good measure to monitor your battery capacity.

There’s a lot of talk on rcgroups about voltage dividers and measuring pack discharge/warnings, so it’s not that unusual; however as Eric says, they have a very flat discharge curve that ends in a steep cliff, so you do need to be pretty careful with divider ratios and how quickly the rate of change is detected - one common ratio I see mentioned is ~1:6.5, but of course it totally depends on how many cells your battery is (ie the starting voltage)

Also remember that you probably don’t want to leave the voltage divider hooked up constantly, as it’ll reduce your battery life as it heats the resistors.