[Dave]

When did these batteries come on the scene? What is their lifespan? I
looked at a Panasonic datasheet and it said nothing about expected
lifespan. Thanks.

Dave

 

[Michael A. Terrell]

When did these batteries come on the scene? What is their lifespan? I
looked at a Panasonic datasheet and it said nothing about expected
lifespan. Thanks.

Dave

It would depend on the way its used. If its used in a PC where the
RTC runs off the computer's power supply most of the time, it'll get
almost shelf life. On the other hand, if it is the only power the life
will be a lot shorter.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Dave]

It would depend on the way its used. If its used in a PC where the
RTC runs off the computer's power supply most of the time, it'll get
almost shelf life. On the other hand, if it is the only power the life
will be a lot shorter.

Well, you used to get almost shelf life out of the batteries that
weren't rechargable, so I don't know what is different. At least with
the old batteries you would have a holder. Now you solder the
rechargable in. Rechargable or not, won't it still die?

 

[Michael A. Terrell]

Well, you used to get almost shelf life out of the batteries that
weren't rechargable, so I don't know what is different. At least with
the old batteries you would have a holder. Now you solder the
rechargable in. Rechargable or not, won't it still die?

Think about it. Any cell (or group of cells) can only be recharged so
may times. If the equipment is used all the time the cell isn't doing
anything, so it should be close to shelf life as long as it isn't
constanly charged at too high a rate. The old PC motherboards that used
a 3.6 VDC NiCad for the RTC charged at a very low current. If it was
dead, the computer had to be on 12 to 24 hours to fully recharge.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Dave]

Think about it. Any cell (or group of cells) can only be recharged so
may times. If the equipment is used all the time the cell isn't doing
anything, so it should be close to shelf life as long as it isn't
constanly charged at too high a rate. The old PC motherboards that used
a 3.6 VDC NiCad for the RTC charged at a very low current. If it was
dead, the computer had to be on 12 to 24 hours to fully recharge.

That is what bugs me. The thing is now a soldered in part and no one
has
convinced me that it will last longer than the product lifespan just
because it
is rechargable.

 

[PeteS]

--------------
That is what bugs me. The thing is now a soldered in part and no one
has convinced me that it will last longer than the product lifespan
just
because it is rechargable.
---------------

Rechargeable Li+ should normally be recharged on a CCCV scheme (with an
RTD for thermal sense). If you are going to (or need to) recharge a
different way, check with the manufacturer. Trickle charging of Li+ is
*not* a good idea.

If the only thing it's running is a RTC in power off, then it's
perfectly possible a non-rechargeable cell will meet the requirement,
saving money and parts. A typical RTC draws less than a microamp in
standby from 3V, so if you were using a small Li non-recharegeable with
120mAh capacity to run only the RTC (typical coin type 16mm diameter),
then you have 120,000 hours of life ~ 13.7 years. So is it worth a
rechargeable? Only if you have to run other things from that battery,
imo.

Cheers

PeteS

 

[Michael A. Terrell]

That is what bugs me. The thing is now a soldered in part and no one
has
convinced me that it will last longer than the product lifespan just
because it
is rechargable.

A lot of PC motherboards were destroyed by leaking NiCads. it was
made even worse because anyone could pull a shunt from two pins on a
header and plug a cheap alkaline battery pack to the board so it would
work for a while, leaving the bad battery pack to ooze and eat the
traces.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida