"The Natural Philosopher" wrote in message ...
Gareth wrote:
On 04/12/2010 20:35, Steve wrote:
We have a solar powered alarm clock which automatically synchronises with the terrestrial time signal. The clock is marked
'PRECISION', 'SOLAR POWER' and 'RADIO CONTROLLED'.

The display became faint and eventually it stopped working. I took a look inside. There was an unmarked AA size battery (leaking
blue liquid which I cleaned up). I measured the battery's voltage which was 1.6V, well above that of a normal rechargeable
(1.2V?).


Was that with it in circuit of after you removed it? If it was in
circuit and being charged when you measured it then 1.6v may be correct
for a normal AA rechargeable battery.

Lithium ion batteries are around 3V when discharged and 4.2V when fully
charged. The 14500 lithium ion cells are AA sized (14500 = 14mm
diameter and 50mm long). However, beware that lithium ion cells can
burst in to flames if incorrectly charged so you want to be sure it
should be lithium ion before fitting one. If you do fit one, I would
recommend that you buy a battery with the protection module built in.

These came up after a quick Google:

http://www.ecrater.co.uk/p/9751735/t...ttery-900mah-2

http://ant-supplies.co.uk/Rechargabl...teries14500tf1

http://www.ledfiretorches.co.uk/batt...batteries.html

try LiFe cells.

Not sure if AA available.

NiZn cells are 1.65v and rechargeable.
They are reputed to come in AA size but I've never knowingly ever seen one.

--
Graham.

%Profound_observation%