Lithium battery advise please
 

I have a 3 volt lithium memory back up battery which I think may be on its
way out. BUT.... its still reading 3.11 volts. Someone has told me to expect
a higher voltage than indicated. Is that right?
I'm going to replace it anyhow, but wondered what the story was.

--
Jack
VK2CJC
ex- MM0AXL, 2M0AJW & GM7POK
yahoo messenger nickname- vk2cjc
www.qsl.net/vk2cjc
www.qsl.net/vk2ep

"Jack VK2CJC" wrote in message
...
I have a 3 volt lithium memory back up battery which I think may be on its
way out. BUT.... its still reading 3.11 volts.

Did you measure it under load?

Put a resistor across it (say 220 ohm) and see if the voltage drops
appreciably.

If so the battery's dead.

Peter

"Jack VK2CJC" wrote in message
...
I have a 3 volt lithium memory back up battery which I think may be on
its
way out. BUT.... its still reading 3.11 volts. Someone has told me to
expect
a higher voltage than indicated. Is that right?
I'm going to replace it anyhow, but wondered what the story was.

Measure it still connected within the circuit and
with the DC power switched off. If it still reads
3.11 volts then it's probably OK. I start to worry
when they read around 2.80 volts or if they are more
that 5+ Years old.

Also, BE VERY CAREFULL if the radio is a later model
Icom or similar Icom product.
Many Icom HF and VHF/UHF radios which were made
in the 1980's had their internal Op-system placed
onto volatile RAM. Bottom line is if you disconnect
the soldered in lithium coin cell of an older Icom radio
you will lobotomize the CPU and you will have to send your
Icom back to the facory for re-programming, assuming they
will still service it at all. Yaesu and Kenwood are NOT affected
by this problem.

see: http://www.icomamerica.com/support/d...s/ram_card.asp

Measure it still connected within the circuit and
with the DC power switched off. If it still reads
3.11 volts then it's probably OK. I start to worry
when they read around 2.80 volts or if they are more
that 5+ Years old.

Thanks for the advise guys. I did measure it in circuit, and out. Same
reading each time. I didn't measure under load which is a damn good idea and
I don't know why I didn't think of that earlier :o)

Its over 5 years old, so I think I'll replace it anyhow. I'm getting some
peculiar things happening with the display and this set is known for this
when the battery goes low. Its a Yaesu TS711.

--
Jack
VK2CJC
ex- MM0AXL, 2M0AJW & GM7POK
yahoo messenger nickname- vk2cjc
www.qsl.net/vk2cjc
www.qsl.net/vk2ep

"Under Load" means different things for different cells. Mem backup Li
cells are most often specd at micro-amps for current load. Excessive
current draw for Li cells can lead to immediate failure. In the area
of 2.5v, in-circuit means "Let's get it replaced now."
Emil
W9NM


Jack VK2CJC wrote:
Measure it still connected within the circuit and
with the DC power switched off. If it still reads
3.11 volts then it's probably OK. I start to worry
when they read around 2.80 volts or if they are more
that 5+ Years old.

Thanks for the advise guys. I did measure it in circuit, and out. Same
reading each time. I didn't measure under load which is a damn good idea and
I don't know why I didn't think of that earlier :o)

Its over 5 years old, so I think I'll replace it anyhow. I'm getting some
peculiar things happening with the display and this set is known for this
when the battery goes low. Its a Yaesu TS711.

--
Jack
VK2CJC
ex- MM0AXL, 2M0AJW & GM7POK
yahoo messenger nickname- vk2cjc
www.qsl.net/vk2cjc
www.qsl.net/vk2ep