Maes

I've been using those for the last 10 years, and rarely bought any alcalines or, God forbid, Zinc Carbon ones.

Essentially, since I started regularly using my walkman for listening to music on the move, I soon realized that it gulped batteries down pretty quickly (I always bought noname walkmans that sounded good, but consumed 2x-3x as much as a brand one).

That's when I switched to rechargeables, in the end of 2000. At first I had to make do with some low-capacity Nicads (600-650 mAh) but even those performed much smoother than alkalines: instead of working OK for 4-5 hours and then gradually slowing down and losing power, they worked for 6 hours straight with constant power until they were completely drained.

With NiMHs, capacity improved dramatically while still mantaining that constant current performance, going well over 10 hours with 1500 mAh cells (back then), and simplifying charging (didn't have to wait until cells were depleted to recharge them).

In any case, since then I've exclusively used rechargeables in CD players, RC vehicles, tools, flashlight, MP3 players, and even digital cameras.

For high-power and IT devices, they are pretty much a must: alkaline and zinc carbon batteries lose current delivery capacity pretty quickly due to their internal resistance, even if they can work for years in low power setting like, say, clocks, film cameras or remote controls. On the other hand, rechargeables perform constantly (and with way higher current output) throughout their discharge.

The only devices that I've found to work unsatisfactorily with rechargeables, are those that lack voltage regulation and thus depend too much on some voltage threshold being exceeded by the batteries, without requiring high current. These include LED flashlights and some types of battery-to-battery chargers, like those found on some RC toys.

(White) LED flashlights, despite being more efficient, need 3.6 Volts just to "break" the semiconductor and start working. Normal 1.5 V cells can handle that, and have some spare voltage to force enough current through them too. Rechargeables however are 1.2 V, and thus barely manage to break the LEDs forward voltage.

Similarly, poorly designed transmitters-chargers that tap directly from the batteries without regulation may not work well or at all with rechargeables.

Also, uses such as clocks or remote controls are not ideal, because they drain so little energy that the batteries will likely self-discharge faster than what will actually be used.