I recently bought a JJRC h8d drone, my first, and after charging the batteries, factory and two extra, went flying. Flew great, but after recharging the factory battery, the drone wouldn't fly again and the lights flashed like during a low battery warning. I put one of the other batteries in and it worked fine. The factory battery still isn't working, any ideas what's wrong?
batteries can just be bad - inspect the contacts, etc. and try to charge it up again. If you are going to stay in the hobby you may want to buy a 3rd party battery charging setup. These give you many more options plus information on the voltage, etc.
What webman said. Maybe it didn't get charged. Check it right off the charger with a multimeter. If you don't have one get one, they are a must in this hobby. It doesn't have to be expensive either, ~$10 or so is fine for our uses.
