Air vs. rechargeable battery? I had two "rechargeable" drills from decades ago. Every time I wanted to use it, I had to plan hours in advance so I could charge the batteries before use. The batteries would self-discharge from one use to the next. When the first drill was lost in a fire, I bought another, similar drill. Same problems, except I noticed--at first--how much longer the batteries lasted in use. After about ten re-chargings, things were as bad as before. Always dead, once charged, they didn't last long before I had to swap batteries. Jucking Funk.
In short, my experiences with "rechargeable" batteries was so negative that I'd rather keep my 80-gallon tank pumped-up 24/7/365 than go through that again. (The system is nicely sealed, so when I'm not using it...it rarely runs.)
Yeah, I'm told that batteries are better now. I wouldn't know from experience--I won't buy 'em. My suspicion is that if you use them every day--so they re-charge every night--they may be OK. If you use them twice a month, you're gonna have dead batteries, you'll have to plan every use well in advance, and you'll spend your days cursing the tools instead of accomplishing something. But that's me.
God bless "fresh-squeezed" air, and LOTS OF IT. As a bonus, the tools run cool...even cold. My aluminum-bodied die grinder has to be operated with gloves, or it's uncomfortably cold after awhile.
I don't know how many times I've heard of guys improperly "priming" the oiling system of engines they've just worked on--and they're complaining about burning-up their 3/8 "cordless" drill motor trying to turn the oil pump long enough to squirt oil over the fenders from the rocker arms.
