I run my batteries right off the charger (more punch).

I always thought you had to let the packs cool down after charging.....ohwell, I'll try that next time I run. Cheers

The reason batteries are hot after charging is because of the amount of current pushed to them by the charger, especially at higher amps (5-6). The batteries have to dissipate the energy by releasing heat. Once you start using the batteries, the excess energy is immediately released by the discharge of using them.
If you have a charger that discharges/cycles batteries, try charging them, then immediately discharging at about 5-10 amps. You'll see the temps drop almost immediately and they will stay cooler through the entire discharge.
The reason batteries can be hot after running them is the high current we discharge them at. When we discharge batteries at 30, 40, 50+ amps they have to struggle to keep up. If we only ran GP3300 (or any other high-quality battery) at 5-10 amps, they would never heat up. They barely get above ambient temperatures at 20 amps.

This is why you should always let your packs cool after running, but you get the best punch if you run immediately after charging. The heat is there for differing reasons in both cases, so it should be treated differently for both.

I'm sure there are plenty of technical descriptions and graphs, etc.. that can be used to go along with this, but this is a simple enough explanation, I hope :)

Yeh, I understand now. Thanks for your explanation batfish - it makes sense. Definately gonna try that next time....:)