TIL something about home fire alarms

[Exterous]

Some models store enough energy to chirp 1-3 times even when disconnected from a battery and home power.

I replaced my smoke detectors and, after replacing the first one, spent a short amount of time thinking the new one or the included battery was dead. Nope just the old one chirping even without battery. Same thing happened for all 5 other detectors

 

[Exterous]

It was starting to feel like this

 

[[DHT]Osiris]

Another fun one, you cannot use rechargeable batteries in most. They don't offer sufficient amperage? I think it is to pass muster.

 

[BoomerD]

Another fun one, you cannot use rechargeable batteries in most. They don't offer sufficient amperage? I think it is to pass muster.

Rechargeable batteries are 1.2 volts. "Regular" batteries are 1.5 volts...the difference tells the smoke detector that the battery is dying...even when it's fully charged.
There are lots of applications where rechargeable batteries just won't work because of that 20% difference in voltage.

 

[snoopy7548]

Just remove the batteries. Problem solved.

 

[Captante]

Rechargeable batteries are 1.2 volts. "Regular" batteries are 1.5 volts...the difference tells the smoke detector that the battery is dying...even when it's fully charged.
There are lots of applications where rechargeable batteries just won't work because of that 20% difference in voltage.

Actually its not just rechargeable batteries .... last time I had a smoke detector die in the wee hours the only AA batteries I had on-hand were "Sunbeam" alkaline's *(aka: Dollar-Store) brand and they were picked up as "dying" brand-new out of the package.

 

[Red Squirrel]

I noticed that a lot with some products, they don't like rechargeables due to the lower voltage. With 9 volts it's even worse as they are around 8.4v. Seems to me, they should put an extra cell and it would bring it up to around 9.6v which sure, is higher than it should be but not that much higher.

What I'd like to see is products that standardize around ni-mh chemistry and just built for taking rechargeables. We should do away with 1 time use cells altogether.

 

[Exterous]

Just remove the batteries. Problem solved.

Some models store enough energy to chirp 1-3 times even when disconnected from a battery

 

[BoomerD]

you need a bigger hammer. A proper application of a BFH will fix just about everything.

 

[NutBucket]

hat I'd like to see is products that standardize around ni-mh chemistry and just built for taking rechargeables. We should do away with 1 time use cells altogether.

In many (most?) applications that would be best for the environment. But correct me if I'm wrong but primary cells are still best as far as long shelf life.
For fire alarms in particular, a lithium primary cell is a great solution since the alarm should be replaced every decade anyway.

 

[BudAshes]

My favorite are the 10 year worry free ones that last 6 months and then the disable function doesn't work so you have to tear it apart to shut it up at 2am.

 

[BoomerD]

In many (most?) applications that would be best for the environment. But correct me if I'm wrong but primary cells are still best as far as long shelf life.
For fire alarms in particular, a lithium primary cell is a great solution since the alarm should be replaced every decade anyway.

Some stand-alone smoke detectors don't have a replaceable battery...and should be replaced every 10 years. I've never had a hard-wired smoke detector that didn't use replaceable batteries for power outages.

 

[NutBucket]

I bought a combo detector a few years back (CO + smoke) that is hardwired and lithium backup. Toss after a decade (when it starts complaining about being old supposedly)

 

[BoomerD]

I bought a combo detector a few years back (CO + smoke) that is hardwired and lithium backup. Toss after a decade (when it starts complaining about being old supposedly)

cool...as long as it actually lasts the 10 years.

 

[NutBucket]

No argument there. The other issue I've seen is apparently you do need to clean it somewhat regularly or it will start false alarming...at the most inopportune times of course.

 

[snoopy7548]

I meant remove the batteries permanently. Problem now solved.

 

[BoomerD]

I put in First Alert combo smoke CO detectors that connect to my Ring alarm system. They use AA batteries. They work fine...but are a tiny but too sensitive. A couple of years ago, I was helping make breakfast...cooking bacon and making toast. I turned away from the bacon pan for a minute...it started to smoke...smoke alarm went off, Ring alarm went off, phone started ringing...Ring alarm monitoring was calling...then came a knock on the door. The system notified the fire department and a cop came to make sure everyone got out...fire trucks were already on the way.

 

[NutBucket]

Wow. That's quick. Last time I had alarm monitoring they would call first to see if it was a real event. Also, need to use different detectors in the kitchen. Somehow they can better differentiate between actual fire and cooking smoke.

 

[BudAshes]

I put in First Alert combo smoke CO detectors that connect to my Ring alarm system. They use AA batteries. They work fine...but are a tiny but too sensitive. A couple of years ago, I was helping make breakfast...cooking bacon and making toast. I turned away from the bacon pan for a minute...it started to smoke...smoke alarm went off, Ring alarm went off, phone started ringing...Ring alarm monitoring was calling...then came a knock on the door. The system notified the fire department and a cop came to make sure everyone got out...fire trucks were already on the way.

At that point you might as well start a fire to make their trip out worth it

 

[pmv]

I guess they have capacitors in them that retain a bit of power, no?
Reminds me of that horrible incident when someone electrocuted themselves by opening up a PC PSU (even though it was not connected to the mains)

 

[pmv]

I am pleased to say I have improved my approach to cooking and am no longer one of those folk who use the smoke-detector as an oven-timer.

 

[[DHT]Osiris]

My favorite are the 10 year worry free ones that last 6 months and then the disable function doesn't work so you have to tear it apart to shut it up at 2am.

Bonus if it's on a vaulted ceiling, and the ladder is in the garage.

On a rack that requires another ladder to get to. Because you only use it to get to the vaulted ceiling fire alarms and LEDs.

 

[MtnMan]

Some models store enough energy to chirp 1-3 times even when disconnected from a battery and home power.

I replaced my smoke detectors and, after replacing the first one, spent a short amount of time thinking the new one or the included battery was dead. Nope just the old one chirping even without battery. Same thing happened for all 5 other detectors

I do not have AC powered detectors, for a reason. As a volunteer firefighter, we responded to another firefighter's home that was burning. He, his wife, and two kids died in the fire, it hit us especially hard.

He had AC powered smoke detectors throughout the house, however the fire started in the electrical panel in the garage and killed power to all the detectors before smoke apparently reached any of the detectors.

Today, with smoke and CO detectors that come with a 10-year battery, I view this as the best option. I also have smoke and smoke/CO detectors mounted near each other throughout the house, plus one that is part of the alarm system and will notify the alarm monitoring company.

 

[snoopy7548]

I do not have AC powered detectors, for a reason. As a volunteer firefighter, we responded to another firefighter's home that was burning. He, his wife, and two kids died in the fire, it hit us especially hard.

He had AC powered smoke detectors throughout the house, however the fire started in the electrical panel in the garage and killed power to all the detectors before smoke apparently reached any of the detectors.

Today, with smoke and CO detectors that come with a 10-year battery, I view this as the best option. I also have smoke and smoke/CO detectors mounted near each other throughout the house, plus one that is part of the alarm system and will notify the alarm monitoring company.

I have hardwired detectors, but they also have replaceable batteries which I change out once a year. If the power goes out, they act like normal non-hardwired detectors.

It should be code to have battery backup on hardwired detectors - lots of fires start when the power goes out and people light candles.

 

[BoomerD]

I have hardwired detectors, but they also have replaceable batteries which I change out once a year. If the power goes out, they act like normal non-hardwired detectors.

It should be code to have battery backup on hardwired detectors - lots of fires start when the power goes out and people light candles.

Our last house had hard-wired smoke detectors w/o battery back-up. I installed battery powered detectors as backups.