Arfurs right hand man
Car: 1.8 Civic SE plus Auto 9th G
Join Date: 31st January 2008
Location: South London,Uk
Thanked 476 Times in 380 Posts
Are you running the radio with the engine off?? if so, with additional amps etc i'm surprised you get 30 mins out of it.
Once its been drained, bumped etc, you need a good 1hr of driving to get it properly charged back up or leave it on a trickle charger to drip feed the recharge.
One tip i've been taught, when charging it up , leave the lights on as you drive as it encourages the re-charge. Don't know how well it works tho....