Sure it could be a electrical issue. If you have a dc voltmeter do a voltage drop test. Start with the battery voltage, write it down, then check the voltage futher down line say the solenoid, it should be the same or very close. Then work your way to the starter, you shouldn.t see any sudden drops in voltage if you do you have found the source of resistance, like a corroded connection or broken wire.
If that all checks out you may have a weak starter. You never said if this was a new battery only you had it on a charger. Even a battery that shows a good voltage reading may still have a bad cell or be weak in amps. Take it to a shop that has a load tester or someplace that can test it on a load tester for you like Autozone etc.
Have you also eliminated the possibility of a parasitic load, if your drive or deck belts aren't suppose to be turning and they are thats too much load.