3.7v standard 510 batty = 180 mAh (OK for short time)
3.7v mega batty 510 = 280 mAh (a bit better)
3.7v 10440 batty = 320 mAh (lasts a bit longer than 280 mAh)
But all of the above work at 3.7 volts.
Well what about a 9 volt rechargeable battery, why can’t this work with a HV atty...