My Smoke & CO2 Detectors are not connected to an alarm system and I am tired of changing batteries. Since the alarms have A/C, couldn't the A/C be continually charging a backup battery in the detector? I have looked without success - where do I find Smoke/CO2 Detectors with rechargable battery backups; do they make such a thing?
When I pursued this a couple of years ago, I concluded that it was probably not code-compliant in US. The suppliers I learned about for this sort of gizmo were in UK.
No. Supervised 12 or 24 VDC units powered by an alarm panel that has rechargeable batteries is the best way to go. Since you're talking a "life safety device", there is no way a manufacturer is going to "stick" a
*supervised* charger system into a 120 VAC smoke alarm/CO detector. The expense would not be warranted and I doubt you could effectively market such a product. Only people such as yourself would recognize the benefits. When deciding between a smoke alarm that costs $110.00 and one that's $9.95, you can pretty well guess which one the builder/electrical contractor's going to use.
In your previous post you'd stated that there may be some European smokes out there with rechargable batteries. Do you have a link to (or information on) one??
A recharged battery voltage will look to a charger circuit as perfectly good even if the battery is actually defective; does not hold charge. To test for a failed rechargeable battery, the smoke detector would discharge the battery - see how long the battery maintains voltage. But that is not desirable since the battery could be discharged just as a fire starts. Furthermore it may take hours to fully recharge a tested (discharged) battery.
Makes more sense (from human safety requirements) to have you replace the smoke detector battery annually and use that removed battery in some other device or toy.
This could change if new rechargeable battery technology that d> My Smoke & CO2 Detectors are not connected to an alarm system and I am
I don't think I saved the search. It started by my looking for/at a UK gizmo that sensed the voltage drop on the 9-volt battery in a detector and could make a contact closure out of that. Seems to me that at that time I saw some recharging circuits for 9-volt batteries in detectors too (not specifically with rechargeable batteries) but don't hold me to it. -- Not much help, was I ;-)
(Ahemmmm..This could probably be accomplished with many AC powered detectors using an LM2937ET-10 from
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