If it is turned off, should not be an issue while charging, however one would have to remember to make sure every one of these lights are turned off before turning on the charger.
You do have several options that may be better..
1 add a current limiting resistor, will drop brightness slightly, would need to do some work to determine the resistor wattage and resistance.
Ideally you would need to insert a ammeter capable of reading 2A or less to get the current draw at battery resting voltage. Then you calculate the voltage drop across the resistor needed (charge voltage - battery resisting voltage).
Divide current draw at resting voltage by the voltage drop the result is the resistance needed.
Example, 13.8V battery, 14.7V charge = .9V drop needed.
LEDs at 13.8V draw 100 ma (.1A)
Gives you resistance of .9 ohms (not common resistance in small wattage resistors would have to sub in 1 ohm)
power dissipated by resistor is .09W so a 1/4W-1/2W would be fine (common wattages)
Look up Ohms Law and Watts law..
2 add one or two diodes in series, each diode will drop .6V to .7V reducing the voltage and current to the LEDs. Doesn't require much work and should get the fixture to a safe voltage/current.
