I've done a couple of things on my planes to help keep the air flowing around the batteries. Since 04 I've used clear packing tape (2-3mm depron also works) to 'seal' the bottom of the canopy to keep the air down around the batteries. The other thing I started to do is to close off the area under the battery tray with some 3mm depron. I attach it to the front cross support, down and around the bottom of the fuse. That way no air goes under the tray and out the exit's, now it goes up over the batteries before exiting. I did this on my Envision and the batteries were 15 degree's cooler, and that was June/July FL weather. I thought about other airflow 'directors' for the batteries, but the canopy tape and air dam seemed to work well enough.

For me I like to break-in my packs for 10 flights, 4 minutes a flight, no full throttle for the first 5. This also gives me plenty of time to practice my rolling maneuvers. I learned how to do the Rolling-8 in F before the Nats with the Sensation this way and it worked out just right.