Rechargeable Smoke Alarm Batteries?

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?

Reply to
DavidB
Loading thread data ...

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.

HTH ... Marc Marc_F_Hult

formatting link

Reply to
Marc F Hult

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.
Reply to
Frank Olson

In my previous post, I considered also suggesting a DIY 'solution' but then thought better.

Then Frank posted this response which is better than my better ;-) Thanks ... Marc Marc_F_Hult

formatting link

Reply to
Marc F Hult

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??

Reply to
Frank Olson

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

Reply to
w_tom

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

formatting link
and a couple of diodes ;-)

Marc Marc_F_hult

formatting link

Reply to
Marc F Hult

Cabling-Design.com Forums website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.