misdiagnosed hardware problem

My cordless phone allows up to 8 handsets - a primary, and 7 secondaries. The primary comes with a NiCad battery; the secondary handsets are thinner and come with a NiMH battery. You cannot switch batteries between primary and secondary handsets: one is AA and the other is AAA. I don't like the "memory effect" of NiCads (see Alzheimer's Battery for details), so Batteries Plus® made a special 3xAA NiMH for my handset; Panasonic doesn't sell one.

That worked great until last week; suddenly, the primary handset failed. I assumed it was damaged when it fell off the table a few days earlier (no physical damage). I tried and tried to make it work, but it refused to hold a charge. I had a decision to make - send the phone for warranty repair and wait (indefinite) .. or replace it, and repair the phone later. I decided to buy - a refurbished handset (thinking the refurb would be in about the same condition as my existing one - true).

I recharged the handset (15 hours) and "registered" it with the base (someone can't simply buy a handset, roam the neighborhood and use my signal - and my long distance). The "register" step is complete, but it says this is unit #3 .. not #1. Hmm. Well, I guess that's okay because the base station (#0) thinks #1 is still active. Time to update the directory on my new handset ...

I pressed the buttons on the base unit to send the directory to the new handset, but (here's the kicker:) it said the directory is full! How can that be? It's the same number of entries as the other units, right? Well, no. As I viewed the directory, I saw many numbers that weren't mine (they were those of the prior owner - apparently someone in Los Angeles - remember, this is refurbished). I purged the prior entries, updated the directory, and now it works perfectly.

It turns out that registration step uploads the directory, but that wasn't documented. Had I known that, I would have (wrongly) assumed that it matched the base station, and not found the prior owner's entries for a few days. Note to Panasonic: the registration step should purge any existing entries, or at least allow me to choose whether to keep them.

Great - everything's working - and now I have a new handset #3. Not sure why, but at this point I wanted it to be #1, like before. Handset #1 shows no sign of life, but (light bulb goes on) maybe I can use the battery from #3 to "unregister" #1! Yes, that worked - meaning that my problem all along was a bad NiMH battery! Argh!

Do NiMH batteries limit the number of times you can recharge them before they go poof (a technical term) - another differentiator from NiCad? Perhaps that's why Panasonic doesn't offer a 3xAA NiMH - only a 3xAAA NiMH? No, that's illogical.

Sure, I could return the refurbed handset, but I have an ethical problem with that. It's not the vendor's fault - I should've diagnosed a defective NiMH, right?

Bottom line? I have a spare handset, which will come to life with a [3xAA NiCad] battery.