Capacitor or Battery?

[George7941]

Found this when I opened up Kidde and SMC smoke/CO detectors. There is a tiny vent hole at the top and there is a pad of moisture/odour absorbent gel taped over the hole.
I am guessing capacitor. If I momenatrily short the two ends together and then monitor the voltage, it slowly starts climbing up from 0V at the rate of approx 10mv/5 secs. I think this has more to do with how electrolytic capacitore work, and not so much an indication that this is a battery.

 

[dishdude]

Looks like it's a CO sensor. Here's an interesting link.

Kidde KN-COEG-3 carbon monoxide/gas alarm teardown

In continuation of Carbon Monoxide teardowns, we now have a Kidde KN-COEG-3 detector designed to handle both carbon monoxide and natural gas in residential u

kuzyatech.com

 

[danez_yoda]

Capacitors do do what you saw. Its called dielectric absorption. You can momentarily short the leads together. If it is a dead lithium cell I would not play with it too much. Some don't like to be discharged to zero and may swell, hiss or pop. pop is bad.

 

[George7941]

You nailed it, dishdude. It is the CO sensor. Thanks.

 

[Owen Lucas]

Don't give this guy an ionization smoke detector.

 

[jhellwig]

Nuclear boyscout.

 

[George7941]

Capacitors do do what you saw. Its called dielectric absorption. You can momentarily short the leads together. If it is a dead lithium cell I would not play with it too much. Some don't like to be discharged to zero and may swell, hiss or pop. pop is bad.

Thanks, danez-yoda. I knew electrolytic capacitors did that. From what you post, it looks like all capacitors do, since they all have a dielectric in them.

 

[y_p_w]

Don't give this guy an ionization smoke detector.

 

[y_p_w]

Thanks, danez-yoda. I knew electrolytic capacitors did that. From what you post, it looks like all capacitors do, since they all have a dielectric in them.

How would you have felt if someone said it was the radiation source for the smoke detector portion?

 

[George7941]

How would you have felt if someone said it was the radiation source for the smoke detector portion?

The city wanted us to drop off smoke detectors for processing the radioactive content. and I have been doing that for decades. But the last time I went, they said to just toss it into the garbage because the amount of radioactive material is very small. Don't know if there has been a reduction in the amount of radioactive material used in smoke detectors.