How long do lithium coin cells last?

[William Sommerwerck]

I have two JVC hall synthesizers, whose memories are backed up by soldered-in
coin cells. Both are over 25 years old.

Both also have leaky power supply electrolytics. I fixed one a few years ago,
at the same time replacing the coin cell with a coin-cell holder, so I could
install a new cell without having to unsolder anything.

This morning I finally got around to replacing the caps in the other unit. I
was about to replace /its/ cell with a cell holder, but decided to measure the
cell's voltage. It was a little over 3V.

This strikes me as an unusually long service time, especially as this unit is
normally turned off, without the AC power supply "gagging" (so to speak) the
coin cell.

Any thoughts?


"We already know the answers -- we just haven't asked the right questions."
-- Edwin Land

 

[Phil Allison]

"William Sommerwerck"

I have two JVC hall synthesizers, whose memories are backed up by
soldered-in coin cells. Both are over 25 years old.

Both also have leaky power supply electrolytics. I fixed one a few years
ago, at the same time replacing the coin cell with a coin-cell holder, so
I could install a new cell without having to unsolder anything.

This morning I finally got around to replacing the caps in the other unit.
I was about to replace /its/ cell with a cell holder, but decided to
measure the cell's voltage. It was a little over 3V.

This strikes me as an unusually long service time, especially as this unit
is normally turned off, without the AC power supply "gagging" (so to
speak) the coin cell.

Any thoughts?

** I still see Yamaha digital effects processors from the late '80s or early
'90s with their original soldered-in Lithium coil cells.

After a voltage check, I use an ESR meter to check the internal resistance.

A new one tests about 10 ohms and well worn ones about 50.

Duds read over 100 ohms.



.... Phil