[JesseK]

It's somewhat easy to account for the robot's actual power draw if you know how to calculate it's theoretical motor load + a safety factor. Multiply it out to get the mAh used, and figure out how long it takes to recharge that amount using the trickle charger. The average time between matches is 30 minutes in Quals at large Regionals (20 mins at smaller ones), so depending on your robot's characteristics and which Regional you attend, you can figure out if your charging abilities meet your minibot battery requirements.

However, in Elims (particularly Finals), that time goes down to ~7-8 minutes between matches. If you make some friends along the way, I'm sure they'll lend you batteries.

edit -- Another thing to keep in mind is that unless the minibot weighs a TON, or is grossly geared improperly, it will reach its goal in 4-6 seconds. Just thought I'd throw that out there. So good design and a shut-off switch when the bot reaches the top should help with cycle times.