Many disappointments with battery powered devices probably are the result of "overly casual" tool selection. Although people tend to think of things like "drill motors" (the common US term to distinguish them from "drill presses") as being pretty generic, there are distinctly different kinds best suited to specific jobs.

Battery powered "drills" are frequently used for driving screws, frequently with the same machine used to drill a pilot hole and make a countersink for the drill head. For driving the screw a relatively low rpm is preferable, and while it's necessary to have sufficient torque to start the screw too "powerful" a driver may run it "clear through the board" unless the machine incorporates an adjustable torque limiter that actually works. Although variable speed motors are fairly common, some are too senstive for good control of the primary speed, and some are insufficiently responsive for quick cut-off when your screw bottoms. "Too big" a motor may have too much "motor inertia" for even a very good torque limiter to cut off rotation quickly enough when that's needed.

If you happen to want to drill lots of small holes through fairly thin sheetmetal, as for body & fender work, a relatively high "motor inertia" may be helpful for breaking past the inevitable "bit grab" as the bit breaks through, although too much inertia may crack your knuckles (and/or break lots of bits) on the inevitable "tough grabs."

A "real pro" would be likely to want separate "drills" for structural fasteners (really high torque) and for plasterboard and trim installation (fairly wimpy torque). A third one for drilling metal might be a good idea. The relative advantages of battery or line power may vary with each kind of use. Most of us can't have enough tools to always have the best for every job so it's worth even more attention to getting what's right for what we do most.

For drilling mostly larger holes, it's generally better to have both somewhat higer maximum rpm available (esp. if a variable speed model is used) and somewhat higher maximum torque if using "bits;" but with lower rpm, retaining high torque, for hole saws and the like.

Older NiCad batteries (and other ancient types) do self-discharge between use sessions, while the newer Lithium Ion types are significantly better at holding a charge in storage. Either kind will die an early death if left too long on a charger, unless the charger is a better than average one and has voltage sensing circuitry to "pulse-trickle" - cutoff when charging is complete, and pulse on only when voltage drops.

It can be very difficult to charge any battery device properly without an indicator that shows when connection is made and separately indicates when charging is at least nominally complete. For most "hand tools" it may be best to have the indicator(s) on the charger rather than built into the tool, but absence of any indicatior is not a good thing.

New rechargeable batteries generally will be "uncharged" when received, and should be fully charged before the first use. Premature use, without a full charge, may permanently reduce the "ultimate battery capacity."

With NiCad batteries, some recommend occasionally completely discharging and then recharging to "reform" them, due to a "memory effect" that reduces capacity with repeated partial discharge/recharge cycling.

Some "authorities" say that once charged, completely discharging, or repeated deep discharge cycling Lithium batteries can greatly reduce their ability to take a full charge, so it's probably best to recharge before the output fades by much.

There is sufficient disagreement on "how to charge a battery" of any type that the best you can probably do is to follow the device maker's recommendations. If there are no instructions with the device you're considering, you might want to look at some alternative devices(?), since that maker probably thinks you just like replacing batteries with the ones he's eager to sell you.

Batteries are generally good for high initial output, but not so good for sustained high output. A "battery powered chainsaw" might be an excellent "brush trimmer" for cleaning the small twigs off what you've cut down with a real saw (or maybe with dynamite); but, as mentioned, probably isn't really a chainsaw. A small line-powered electric chainsaw can be handy for working on the ground, but I probably wouldn't take mine up a tree. (Maybe I should say "send mine up ..." since I ain't likely be up there for any reason.) I do also have a small gas powered one for when the electric isn't quite up to what's needed, but some jobs just aren't worth the mixing, fueling, etc. required for all that gas power. And if you don't have enough big trees to need one, a bigger chainsaw doesn't get you much in real macho points from the pros. If you don't need a good log splitter at least once a year, a 14" - or maybe up to about 20" - chainsaw will probably do about all you're likely to need. (Of course, that's just one opinion, and your needs are different.)

An alternative to battery powered tools, used quite handily by one acquaintance, is to strap an inverter onto the side of a truck battery and use common (and much cheaper) line-powered tools. He hasn't taken my advice to put the battery on a 2-wheeled dolly (yet). He does have a small almost-a-truck so he's a little space-limited. His rig works quite nicely around the camp.

John