Charging SLR Battery?

Hi, I'm going for a day out tomorrow so will need my battery fully charged. I need to charge my battery it has three bars left which means full but it will go down to two bars really soon, can i charge it tonight until it is FULLY charged or will it damage the battery?
I have a Canon 1000D and a Nikon D3000

It shouldn't be a problem. I've frequently charged SLR batteries from various charge levels on my DSLR and I have yet to see a real battery life drop off. I once took a three week vacation and forgot my charger, and it lasted the entire life with no issues - and I ended up taking over 800 pictures on it.

Although in the future, if you're worried about this becoming a consistent problem, I'd suggest buying a second battery.It'll alleviate a lot of your worries.

I think you should go with Canon LP-E6 Battery Pack for Select Canon Digital SLR Cameras

Compatible With Select Canon Digital SLR Cameras
Rated at 7.2V, 1800mAh
No "memory effect" -- May be Partially Charged Without Reducing Battery Capacity
Compatible With Canon LC-E6 Battery Charger