I'm not quick to recommend rechargeable batteries for the 41 unless you're using the card reader or the bar-code reader wand a lot. My own 41cx went two years on each set of alkalines even with everyday use, until I got a double extended memory module which seems to have more leakage current and took the battery life down to around six months on a set of alkalines, again with everyday use. If you use rechargeables, you'll have to have two sets if you have to remove one set to put it in the charger, using the second set to preserve the memory while the other set is getting charged. The price of two sets of rechargeables plus charger will buy many, many years' worth of alkalines, and the rechargeables need more-frequent attention because of their self-discharge rate. Yet another point is that if the rechargeables are 1.2V, my own 41 would show the low-battery annunciator all the time, because it comes on at 1.2V. Again, I don't recommend rechargeables unless you often use the card reader or the bar-code wand. I have the tape drive, but I have enough memory in my 41 to perpetually keep everything I need in it, so I virtually never have to access any kind of external storage.