Rechargeable batteries

[#1]

How long should they last?

Had my BT8500 phone for about two years and we are now finding that any more than about 15 minutes on the blower and they go dead - with one handset lasting slightly longer than the other. When the phone was new call time was a lot longer I'm sure of it.

Checked out the existing batteries for type and make and they are some obscure outfit that I've never heard of so I guess any new ones should be Duracell's or something similar. The thing is they ain't cheap are they?    

[#2]

I recommend Eneloop 4th Generation recharge capacity 2100 times

https://metaefficient.com/rechargeable-batteries/best-rechargeable-batteries-battery-chargers.html

This is a good source https://www.7dayshop.com/products/panasonic-eneloop-batteries-aaa-750-mah-rechargeable-battery-pack-...

[#3]

I have eneloop batteries in my home phone and baby monitor and they are fantastic.

[#4]

Mine are marked as AAA 1.2v SANIK 750mAh. 

Do I have to stay with those figures? 

PS. Thanks for the links, looks perfect 

[#5]

That is normal - the higher capacity ones tend to have fewer recharges which isn't what you want in a DECT phone

[#6]

Higher capacity .... =  longer usage time... if you aren`t "constantly" on the fone... then less charging cycles is a good thing..

For longer usage time,.... read... you can leave it off the charger for longer periods... without it losing charge....

[#7]

Well with one Mrs and three daughters........ 

[#8]

Rechargeable batteries last longer if given some work to do. Have you perchance been in the habit of leaving them on the base/charger for long periods?

I've had my quad DECT system for five years, and all the (not famous name) batteries are the originals, and still giving good talk times. They go back on the base/charger when the display is down to one bar.

[#9]

I do recall that was the advice with ni-cads - let them run down and as you say 'do the work' but yes, I guess they spend more time on charge than off so...... 

[#10]

Makes a standard wired telephone with a long handset cable look like a far better option...

[#11]

And to think there was a time when I thought push button phones were a gimmick and that the idea would never catch on. MInd you, I said that about rear windscreen wipers as well!.

[#12]

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@Oldjim wrote:

I recommend Eneloop 4th Generation recharge capacity 2100 times

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Before you put Eneloops or any other NiMh chemistry battery in the phone have a check in the handbook for the phones. NiMh batteries need a different charge profile from NiCad. Recharging NiMH's in a charger not designed for them can be dodgy. Particularly something like a DECT handset when they spend more time on charge than off.

If you use an external charger I would go with Oldjim's recommendations. I use 7day shop's own brand "Good to Go" batteries in cameras, flash guns ad torches . They are excellent.

For my DECT phones I buy cheap NiCad's off Ebay and swap them every couple of years - the long periods they spend being on trickle charge and the multiple short discharge/recharge cycles seems to kill them however high quality they are. Only four phone calls/day is about 1500 discharge/charge cycles in a year.

The option of leaving the handset off the charger to put the batteries through a discharge cycle every so often is fine - but round here Murphy's law says that the point that the handset is at its lowest and ready to be put back on charge will always be the point at which SWMBO wants to spend an hour or so on the phone to someone!!

[#13]

The Eneloops worked just fine on my phones and just to be absolutely clear - the existing batteries are Ni-MH so NiCad are not recommended

[#14]

@wisty I was under the impression that NiCd cells were being phased out wherever possible due mainly to environmental concerns?  Whilst NiCd cells have stricter charging requirements, NiMH are not so limited (apart from using a suitable charger!) and can be put back on the charger at any state of discharge.

I'm with Oldjim regarding MiMH cells. My Gigaset phones (which I believe OJ also has) came with NiMH when new, and although I haven't needed to replace any yet, when the time comes I'll probably use Eneloops.

It's not a good idea to completely flatten either of the cell types but any decent modern device will switch itself off before the cells are discharged to too low a voltage.  An example of something which will flatten cells too much if left switched on is an old fashioned torch with an incandescent bulb.