A better method the manufacturers could use is inserting a bridge rectifier between the charging jack and the circuitry. This would always direct the proper polarity in the right direction, irregardless of how you hook up the charger. I still don't think that you would be able to peak charge the battery due to the voltage drop across the diode.

How hard is it for you to remove the battery to cycle it outside the case?
Why not just leave it on until you reach between 1.0 and 1.2 volts/cell?
That is what I do. Make sure you don't live near a field where you could cause interference. Or, do it at the field while your pin is up. A good day of flying should get you pretty close to this.

KW_Counter