You can install an extra battery no problem as long as you hook it up right -to- and +to+ Dont put in anything to big or your alternator will struggle. You surley dont need to have you flashing lights on all the time. how many crooks do you have there .
PS if your using your quad to harrass atv users for minor offences. you know loud pipes ect. You would be better to hook the negative terminals to the positives.
That will give a much more satisfactory result?????