Many Transmitters have a diode between the charging jack and the battery connection. I assume this is basically to prevent damage in the event of reverse connection of the charger.
Battery cyclers cannot discharge with the diode present, and some won't charge either. There seems to be a couple of solutions:
Replace the diode with a wire link or Replace the diode with a polyswitch
#1 would leave no protection, and #2 would provide some, but I am not sure how fast the polyswitch acts. However in both cases the diode is out of the picture. From my school days electronics, I seem to recal there will be a0.7v drop when a diode is in circuit. If, in the above cases, the diode is removed, will this have any effect on charging as the voltage reaching the battery is now 0.7v higher than it was before?