Rechargeable Battery For Clock

[securespark]

How I miss electric clocks!

We have a slew of clocks round the house and they used to run fine on non-rechargeable batteries.

Now we have swapped to rechargeables, they seem to conk out more frequently.

I have tried larger capacity batteries (the Ikea Ladda 2450), but the problem is still there.

Could it be the reduced voltage?

 

[Tigercubrider]

I'd think so.

 

[ericmark]

More likely self discharge.

 

[RandomGrinch]

Yes!
With a starting voltage of about 1.3V and a single AA battery in a clock, there won't be much tolerance.
Although the discharge curves of NiMH are relatively flat at 1.2V until about 20% charge remaining.
1.5V AA rechargeable LiPo's are starting to become available, although not yet from reputable suppliers!

EDIT:
As others have said, self discharge is more likely. Online research (take that as you will! ) Suggests some mechanism will run on 0.2V, when others will fail at 1.2V!

 

[flameport]

Clocks are one of the few devices that are ideally suited to zinc carbon AA batteries, such as the cheapo ones you can get in Poundland and similar.
Most other types including rechargeable are intended for high current intermittent use, which clocks are not.

 

[AndyPRK]

I’ve not had this problem with white eneloop

 

[JohnD]

Eneloop have an exceptionally low self-discharge

 

[ericmark]

2500 mAh don't seem to last long in a clock, but 700 mAh do, it depends if designed for high capacity or low self discharge.

 

[securespark]

I’ve not had this problem with white eneloop

Shall order some!

Thank you folks, that's very helpful.

 

[Harry Bloomfield]

I have tried larger capacity batteries (the Ikea Ladda 2450), but the problem is still there.

Could it be the reduced voltage?

In part it is that the fully charged voltage is a bit lower, so after a little use it drops below the threshold for working, but also rechargeable are not suited to long and slow discharges anyway.

 

[securespark]

2500 mAh don't seem to last long in a clock, but 700 mAh do, it depends if designed for high capacity or low self discharge.

That may explain why the higher capacity rechargeable batteries I bought for my DECT phone conk out even when the display shows full charge.
This happens most often when using speaker phone.

 

[securespark]

In part it is that the fully charged voltage is a bit lower, so after a little use it drops below the threshold for working, but also rechargeable are not suited to long and slow discharges anyway.

Cheers

I will order a pair of the white eneloop and if they aren't an improvement, I shall revert to standard 1.5V batteries.

 

[JBR]

Sorry for straying off-topic, but I bought a mains-powered mantel clock from a second-hand shop a few years ago. The same sort of thing which was common among our parents/grandparents many years ago. Having checked its condition and connections, it has worked perfectly ever since and, apart from power cuts, has never gone wrong.
Who would bother with battery-powered clocks?

 

[Wayners]

Lithium aa battery with last for years but cost a bit more.

Just thought I'd mention
With things like kitchen scales that use button cells I've converted to usb rechargeable which is easy if you like to tinker.

 

[Harry Bloomfield]

Sorry for straying off-topic, but I bought a mains-powered mantel clock from a second-hand shop a few years ago. The same sort of thing which was common among our parents/grandparents many years ago. Having checked its condition and connections, it has worked perfectly ever since and, apart from power cuts, has never gone wrong.
Who would bother with battery-powered clocks?

Anyone who wanted to have a clock which didn't need to have a socket for it and a flex dangling from it, plus possibly someone who a clock which was kept accurate by MSF.