AAA Cells for a DECT 'phone.

Be careful that such high Ah claims might be true only in some perverse test that bears no relation to normal use (or simply an outright lie).

I found the old red cased Aldi/Lidl NiMH rechargeables to be surprisingly good. Better than some well known brands in capacity. (and that is real measured capacity rather than labelled capacity)

I wouldn't worry about that. Advice on Usenet can be worth less that what you have paid for it. There is no reason not to put any matched set of batteries of the right chemistry that will fit into a phone.

The set should all be replaced at the same time even though you will probably find one very sick cell and a couple of also rans. Out of a set of three or four handsets if you test the batteries on a smart charger you may be able to find a usable set of batteries or maybe two.

Typically in this sort of configuration one weakest cell is completely destroyed by its stronger neighbour(s).

The only brand of batteries I actively avoid at the moment is Duracell. I have had too many of them leak in service past couple of years.

When we started having problems with the unbranded AAA batteries in our Gigaset handsets, I went out and bought some branded (probably Duracell) batteries of higher capacity, taking care that they were the same technology (probably NiMH).

When we continued to have problems with the handsets running out of battery with no warning - typically they'd go from "fully charged" to "critically empty" in a couple of seconds - I contacted Gigaset support and they said that the batteries were "too powerful", and we should have used ones with the same mAhr rating as the phone was supplied with. I remember asking in this newsgroup whether this made any technical sense, and the consensus was the same as the conclusion that I'd reached - that this advice was pure bollocks.

We've since replaced the Gigaset phones with BT8500 ones, and they too suffered from the supplied batteries running out very quickly. However in this case, the replacement batteries that I fitted (Philips HR03, 1000 mAhr) have lasted for several years without starting to lose the ability to hold charge.

Like everyone, we tend to leave the phones on the charging stations whenever they are not in use - mainly to make sure that the batteries are always fully charged for when we make/answer a call. The problem with charging and then removing from the charger when full is that the batteries then start to discharge, so they could be almost flat by the time the phone is needed. It's the same problem as with mobile phones or anything with rechargeable batteries: if the batteries are going to self-discharge or discharge as a result of background usage (listening for incoming calls) then you want to make sure they are kept topped up so you get full usage out of the charge.

Brian Gaff pretended :

My set of BT8500's were bought as 'returns'. They came with sets of batteries, but the sets were all different. Some lasted 12 months, some

If 300mAh will do I've had poundland ones last way over 1,000 cycles, but one does get the occasional dud

NT

I've got several here. It's true some kill batteries - but not all. Panasonic seem the best of the ones I've got.

I don't know what make hers is but she bough it in 2012, so it's not done too badly.

Possibly the problems is that the batteries are not cycled. On my old DECT pair of phones one tended to sit on the charger 24/365 and was hardly ever used. The other one was used to answer/make 99.9% of the calls. The batteries in the phone that was hardly ever used and remained on its charger was the one where the batteries failed whilst on the other one the batteries still held their charge and provided power quite well. I did however replace the batteries in both phones at the same time.

I wouldn't expect not cycling to be the cause though. You never know whether NiMH will last very well or less so. With any brand there seem to be weak ones among the gooduns.

NT

Well, I did say 'much' :-) And costs start to go up a lot for those higher capacities.

Yes - I've noticed that as an issue. Of the 6 or so makes that I have, only the Eneloops fit in my Logitech mouse without some forcing. But IIRC, nothing else is that bothered.

Not sure about that - IME larger capacity low discharge cells have been fine in my 20 year old Panasonic phones for the past 5 years.

Mind, the phone only gets used once every few months, apart from to receive nuisance calls.

My "sat in the charger all day" handset get el-cheapo ones from Poundland, on the basis that lower capacity batteries can tolerate a continual float/trickle charge better than higher capacity ones.

The other handset that is usually off the base station has 800mAh low self discharge batteries.

Ours do that as well. Very annoying and when a handset has decided it has flat batteries it can be a right PITA to get it to power back up when a different set of batteries are inserted. Say from another handset that has been stood in its chrager and shows "fully charged" or even ones straight off an "intellegent" charger showing green.

When you measure the off load voltage of the "flat" batteries they are both very simsilar and well above the nominal 1.2 V. Shove in the charger it'll do it's "checking" "equalising" and charge 'em for just a few minutes before going green.

Hum, I wonder if they have a "clever" charge circuit that monitors the charge/discharge and it gets "confused" some how?

I had a set of three gigaset handsets and a oouple of spares which all failed in that way. As far as I could tell this was because of gradual failure of a DC to DC converter which was ultimately only able to maintain the internal working voltage when the phone was on charge or the batteries slightly over nominal voltage. It continued to charge fully charged batteries - perhaps it was sensing the output of the DC to DC convertor to estimate battery voltage?

I had a similar experience with my Gigaset DECT phone which I got off Freecycle. The battery indicator showed Full but when I tried to make a call the indicator went to Empty, so I guess the batteries had gone high resistance.

I put in new charged batteries of higher capacity than the originals, nut the indicator stil said Empty and I couldn't make a call. I had to put the phone on its charger until the indicator showed some charge before the phone would work.

I suspect the phone doesn't monitor the voltage, it just calculates the charge from the charging period. The indicator is now suspect because the batteries have twice the capacity of the originals, so when the indicator shows Empty the cells are only half discharged.

In other words their clever charge circuit is really dumb.