Lithium 1.5v AA battery shwoing 1.7V?

[DW1961]

I have a carbon monoxide alarm in my house and it's giving me the beep beep alert. I checked the batteries with a MM on the 1.5V setting, and they all show 1.7V.

1.7V seems really high, and if they are 1.7V then they aren't worn out. So I'm wondering why I'm getting that low battery alert?

[Peabody]

1.7V is normal for that battery under no load or very low load.  You may be getting a battery warning, but not necessarily a low battery warning.  The detector may not be designed to handle the high voltage.

[tooki]

Wikipedia says

Lithium-iron disulfide batteries can have an open-circuit voltage as high as 1.8 volts but the closed-circuit voltage decreases, making this chemistry compatible with equipment intended for zinc-based batteries. A fresh alkaline zinc battery can have an open-circuit voltage of 1.6 volts, but a Lithium iron-disulfide battery with an open-circuit voltage below 1.7 volts is entirely discharged.

Sounds like the batteries are actually empty. Test them under load, chances are the voltage is collapsing.

[DW1961]

Guys, I did test them under load using the MM battery test function, which I thought puts it under a load (not a full load of course).

I tried alkaline AA batteries--same thing.

These batteries have been in that unit for about a year with no problems. The unit was manufactured in 2011, so it may have been giving me an end of life alarm. From what I've just read, the intended working life of a carbon monoxide alarm is 5-7 years.

"End of Life Warning – Seven years after initial power up, a Kidde CO alarm will begin chirping every 30 seconds. The chirp will not stop until the unit is powered off." That's what it is doing.

Even though it says 2001 on it, it may not have been powered on until 2013. I just bought a replacement--same brand same model and should just slide back on teh wall plate.


Is there anything I can tear apart and salvage from it, like a PCB, etc--hehehe.