Dan, Actually, the voltage is slightly lower with rechargeables than with alkaline batteries, if memory serves, 1.5 for alkalines and 1.3 for nicads. This could well be different for NIMH batteries; I don't know. I did use nicads briefly when I first got the BP and found the behavior of the unit was just a bit less stable when using them. I had a few more lockups etc. I should also mention that this was a few firmware updates ago. But I figured it would be better on several fronts just to use alkalines since they last so long in the bp and my reading is mostly with the double talk. Some folks have had trouble with the battery clips in the unit and I'd just as soon not disturb them if I don't have to. Lou ----- Original Message ----- From: DanFlasar@xxxxxxx To: bookport@xxxxxxxxxxxxx Sent: Thursday, December 15, 2005 12:21 PM Subject: [bookport] Re: the d e f command In a message dated 12/15/2005 9:24:27 A.M. Central Standard Time, loukolb@xxxxxxxxxxx writes: rechargeable batterries in the BP. I know many do with no problem but I figure the less I mess with the contacts, the better. Lou Rechargeables are exactly the same size and shape as non-rechargeables. If they are freshly chazrged, there is little difference in current between them and non-rechargeables. I don't see why it should cause any sort of a problem. Dan