# Rechargeable 9V for Smoke Detector



## zoulas (Jul 5, 2012)

Hello, is this even worth it? Would this last as long as the Alkaline 9V (2 years+) What do you guys use in your smoke detectors and clock backups? Thanks


----------



## alpg88 (Jul 5, 2012)

no it is not worth it. they wil self discharge sooner than alkalines will drain.
i use litium 9v energizer cells in smoke\co alarms, and dmms.


----------



## moldyoldy (Jul 5, 2012)

In general I agree that rechargeable 9V batteries are not worth the bother in the usual battery-operated smoke or CO alarms.

However my US location has a continuing problem with at least a dozen power failures a year. The power people tell me that is because of old buried wiring in the neighborhood. My house has 3 AC-powered combo CO/Gas alarms, 2 with LED display, 1 with LCD display, and with a 9v backup if the AC mains fail. Usually a normal alkaline 9v battery will discharge during the length of an AC power failure. So to solve that steady waste of alkaline batteries, I use the Maha 9.6v LSD batteries. Although they cost ~$10 each, over the years, those rechargeable 9.6v batteries have proven to be cost effective. and yes, if the 9.6v Maha battery ever runs down, the low-battery warning does sound, even for a day if we are out and about.


----------



## HotWire (Jul 5, 2012)

To be safe you should check with your local fire department. I use name-brand alkaline batteries in mine and change them twice a year. That smoke alarm could save you and your family. Maybe your house!


----------



## moldyoldy (Jul 5, 2012)

HotWire said:


> To be safe you should check with your local fire department. I use name-brand alkaline batteries in mine and change them twice a year. That smoke alarm could save you and your family. Maybe your house!



oddly enough, the city fire inspector did check all of my many alarms (in each room) in the process of inspecting the basement bathroom addition. I did not know that the fire inspector could go over the entire house for the sake of inspecting a basement bathroom. According to the bathroom installer, the fire inspector pushed all of the test buttons on the battery operated alarms. For the AC-powered gas/co alarms, he pulled the AC transformers and then pushed the test button. All passed. The indirect reason why I discovered what he did was because he did not plug in the AC transformers after the test. In the evening all of the low battery beeps were going off whereupon I discovered that the transformers were unplugged. grump. certainly an independent test.


----------



## moldyoldy (Jul 5, 2012)

edit: I believe in redundancy in smoke/gas/ionization product sensing. Each of the bedrooms has a combo ionization and smoke alarm plus a CO alarm and three more in the open areas of the hallway and liviing room. Every room in the basement has a combo ionization and smoke alarm. The top of the basement steps has a combo ionization and smoke alarm plus an ionization alarm of another brand. There is a co/gas alarm near the garage door and another near the gas utilities (furnace & water heater) and another in the open side of the basement. 

Why? I received active fire fighting training from several US organizations including the USFS - all well used, be it business fires or forest fires or car fires. The last fire was my neighbors house - knocked down a second floor room fire before a police officer demanded that I exit, which I did - whereupon the fire eventually gutted the second floor.


----------



## zoulas (Jul 6, 2012)

Thanks, I will probably go with 9V Lithiums like the Energizer Advance.


----------



## TooManyGizmos (Jul 6, 2012)

~

I think the lesser expense of 9v Alkalines is good enough .....

if you change batt's twice a year.

Why run down an expensive Lithium .... during power failures ?

~


----------



## Fresh Light (Jul 6, 2012)

Tenergy Centuras (LSD) 9V are only 3.99 or less with quantity. I almost exclusively use their larger c and d cells in both regular and lsd, and they are the best I've used.


----------



## bob_ninja (Jul 10, 2012)

Well in my region 9V are expensive. I guess low volume or something.
So I use Maha's NiMH 9V cells. Certainly paid for itself by now, even if I charged them only about 10x so far.
Between remote controls, DMMs and alarms, I am always scrambling for 9V batteries.


----------



## czAtlantis (Jul 10, 2012)

Don't know if for smoke detector is ni-mh economical (depends on power consumption...I would say if the battery is drained in less than 1 year, use ni-mh)but where I live I can buy alkaline 9V battery for 2.5-4USD! While I just discovered on ebay I can buy for example Yuasa LSD Enitime 9V for 11USD including shipping. So after 3recharges it pays for itself. I use in some multimeters Maha powerex Imedion LSD and they perform quite good! But they were expensive as I remeber...
Btw i just found out I need more batteries - what do you think about those Enitime cells? Are they good? Or those Tenergy Centura? Which is better? What other LSD 9V batteries can you recommend? Those Imedion cells are very good but too expensive...Thanks


----------



## Shadowww (Jul 11, 2012)

czAtlantis said:


> but where I live I can buy alkaline 9V battery for 2.5-4USD! While I just discovered on ebay I can buy for example Yuasa LSD Enitime 9V for 11USD including shipping.


Well, to be fair, you can also get alkaline 9V's for 1.4 - 1.5 USD a piece *on eBay.*


----------



## 901-Memphis (Jul 12, 2012)

I would *NEVER* use a rechargeable in a smoke alarm. I would only use Alkaline/Lithium.


----------



## czAtlantis (Jul 12, 2012)

WTF? my post diappeared! I saw some error messages about database and now it is probably restored from previous backup...Anyway, shadowww: - for my location I can get from ebay some non-brand alkaline 9V battery for 2.5usd or duracell for 3usd...with larger quantites it will be better but I can't go under 2usd/battery...and I think it is better to have rechergeable if they pays off after 4discharges.
901-Memphis: Why not? Are there any issues with that?


----------



## donutz28 (Jul 12, 2012)

I don't care to use alkalines in my smoke detectors. After you replaced a few leaky batteries, you'll want to use something better. 

I would never use rechargeables. They'll die too quickly and you might not get enough 'beeping' alert to know that they are dead. 

I've been using Ultralife 9v lithium cells. And, I started to use the 9v lithiums from Energizer. 

The problem with ebay and some online stores is that you're hoping that you're getting that Duracell/Energizer or other name brand alkaline. I've learned the hard way that many are knock offs. I only buy alkalines locally(target/walmart/riteaid/cvs/walgreens/sears....) and don't mind paying a little more. I also don't need to buy in bulk and worry if they'll expire before I get to use them all.


----------



## 901-Memphis (Jul 17, 2012)

I have never had a Duracell/Energizer alkaline leak in my smoke detector, but i guess i am just lucky?


----------



## HarryN (Jul 22, 2012)

901-Memphis said:


> I have never had a Duracell/Energizer alkaline leak in my smoke detector, but i guess i am just lucky?



Good question. I have had enough alkaline cells (mostly AA and D size) leak that I mostly don't use them. As far as 9V alkalines in a smoke detector leaking, you might now see it because the cell will likely go "low" and the detector will buzz for a change before it leaks.

Some of my smoke detectors are easy to reach, but a few need a ladder. For that reason, and being lazy, I just prefer to use a Li 9V in all of them.

I can see how annoying it would be if you loose power regularly though, and it ran down the cells. In that case, maybe R cells do make sense. That, or putting that circuit on a ups.


----------



## czAtlantis (Jul 22, 2012)

Best solution is to have all detectors connected to common system with backup. I really can't imagine just having few battery operated $10 devices protecting my house. We have security system with smoke detectors connected to it and it is backuped by lead-acid battery. Main advantage is it will also send text/call when anything happen over GSM. Only standalone detector with 9V battery we use is for carbon monoxide in a boiler room.
btw - on my CO detectors it says "don't use lithium battery" - maybe because there will be little time between low battery alarm and complete discharge?


----------



## mattheww50 (Jul 22, 2012)

Actually my prefence at this point is for smoke detectors with builtin lifetime Lithium batteries. When the battery dies, it is time to replace the smoke detector. These things should last
about 10 years. The power demands for a smoke detector, except when the alarm goes off, are measured in microamps. I'd be willing to bet that the self discharge rate on a
rechargeable 9V batter is higher than the current requirement.

Typical capacity of a high quality, fresh 9V alkaline battery at the drain required for a smoke detector is about 800mah. A year is about 8800 hours, most batteries actually last longer than a year so average current drain cannot exceed about 90 microamps. 

The only issue I am aware of with the use of Lithium cells in these devices is Lithium's are more sensitive to low temperatures than Alkalines or NiMh.


----------



## czAtlantis (Jul 22, 2012)

Lithium cells are more sensitive to low temperatures? really? In my experience it is not true at all - alkalines and Ni-mh don't work at low tempteratures but lithium cells work just fine.
Also 800mAh seems to be overrated - I would estimate the capacity around 500mAh max


----------



## moldyoldy (Jul 22, 2012)

ref detector current draw: An ionization detector draws very little current. A smoke detector uses a small "light" to detect hazing of the atmosphere inside the chamber - which draws more current. Then the CO detectors which lately use AA cells draw still more current. Finally the gas detectors draw the highest current of all. 

What are some actual currents? no real idea except by observation of battery life and some calculated guesses. I no longer have a 'scope and my fast Fluke DMM failed years ago so I am not able to measure the pulse of current when the detection is turned on.

Edit: I eliminated nearly all of my ionization-only detectors in favor of the combo systems. There is considerable evidence concerning slow smoldering fires and the slowness of ionization-only detectors to sense the "fire".


----------



## HarryN (Jul 22, 2012)

My (very limited) experience with house fires is that even a fairly small one will pretty much ruin the house and most of the contents. It is not so much the fire, as the smoke - its just insidious and tenacious.

We use smoke alarms as a way to warn us to get out, not to save the house / contents. The fire depts. in CA operate this way as well, pretty much just contain a fire to keep it from spreading to other homes, rather than really focus on trying to save anything.


----------



## 45/70 (Jul 22, 2012)

czAtlantis said:


> Lithium cells are more sensitive to low temperatures? really? In my experience it is not true at all - alkalines and Ni-mh don't work at low tempteratures but lithium cells work just fine.



As far as I know you're correct. Without looking it up, as I remember, alkaline cells begin to drop in performance when their simply "cool", not even "cold". NiMH cells do pretty well down to freezing temps, or maybe a bit lower, NiCds do a bit better. Lithium primary cells on the other hand, hold up well at temps well below freezing.

Lithium-Ion cells on the other hand fall into about the same category as nickel based cells. As the technology advances though, they're getting better, at low temps.

One question though, I thought I was the only one that had rooms in their house with Winter temps below freezing! I wouldn't think temperature in the location of most folk's smoke alarms would really be much of a concern, as far as battery type anyway.

Dave


----------



## WDG (Jul 25, 2012)

There has been some discussion a few years back on this topic here: *9V NiMH only 7.2V?*
And here:*Are there any NIMH low discharge 9 volt batteries?*

The short answer: Use Alkalines, changed twice a year, unless you're willing to go to a good deal more trouble and/or expense. _They're relatively inexpensive, compared to rechargeables, and will still have plenty of reserve to power the alarm when you change them every six months._

In general, *alkalines give the best cost/safety value in this use*. 

The *lithiums* are great, but expensive and have a steep end of life curve that could cause you to miss a low battery alert. I have used them in the past, and concluded they were *not worth the expense for this use*. I would probably change these annually, if I were still using them.

*Rechargeables* should only be trusted if you're willing to religiously *recharge them monthly*, else they might not have enough juice left to power the alarm in an emergency. Also, not all "9v" rechargeable batteries are actually 9 volts. This may or may not be a factor, depending upon the design of the alarm.

_That said_, I use *iPower 9v li-poly* rechargeable batteries (about 500mAh) in ours. I recharge these monthly, so they've got plenty of reserve to power the alarm when called upon. *This is probably the single most expensive way to power a smoke/CO2 alarm*, so I would never have purchased them for this application. These are extra batteries I happened to already have for powering wireless mics & radios.


----------



## jruser (Jul 25, 2012)

I don't know anything about it, but my detectors are wired into what I assume is AC power and maybe networked with the other detectors.

When I moved in, all of the detectors were running some "Super Heavy Duty" generic 9v batteries. 2 of them have since died, which I replaced with Duracell. In another 1 of them, I replaced the battery with one of the Maha LSD 9.6v batteries as a test around 18 months ago. It still hasn't started giving me the low beep.


----------



## 901-Memphis (Jul 26, 2012)

jruser said:


> I don't know anything about it, but my detectors are wired into what I assume is AC power and maybe networked with the other detectors.
> 
> When I moved in, all of the detectors were running some "Super Heavy Duty" generic 9v batteries. 2 of them have since died, which I replaced with Duracell. In another 1 of them, I replaced the battery with one of the Maha LSD 9.6v batteries as a test around 18 months ago. It still hasn't started giving me the low beep.



LSD 9v rechargeable might be good if you have AC power and the battery is only for backup, but its something i would still keep an eye on to check your cell and make sure they are healthy. Using a rechargeable in a dc only detector is a whole nother story. 


Even if you have a/c power detectors and you have frequent power outages you may find yourself draining the cell often. I guess one could say it varies by application. Persoannly i use Rayovac 9v alkaline since they are one of the better price to performance out there.


----------



## Sub_Umbra (Jul 26, 2012)

If a rechargeable is chosen, insure that it is of a standard *form factor* and will, in fact, fit in the alarm. Non-standard form factors seems to be a recurring issue with 9V rechargeables.


----------

