Originally Posted by GBear
That doesn't mean the battery is "weak." Again, "weak" is vague. You mean it's a dead battery or it is uncharged? It won't fire at all. But comparing a 8.4V and a 9.6V, the 8.4V is "weaker" I guess but will/should not lower your FPS. The battery isn't propelling the BB, the compressed air generated by the piston and spring do.
If you want to see a 9.6V with a "weak" charge left fire just watch my VFC M4 SOPMOD full loadout video in the media section. Only a COMPLETELY DEAD battery will not fire at all. It could barely retract the spring and gave just a little pop when pulling the trigger. After I recharged it, it was firing full throttle again.