EEVblog Electronics Community Forum
General => General Technical Chat => Topic started by: Halcyon on May 19, 2016, 01:41:52 am
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I had the pleasure of being woken up at 0130 this morning to the sound of one of my smoke alarms chirping away every 30 seconds to let me know the 9v backup battery was low. As you can imagine I was impressed having to fetch a ladder to remove the damn thing at that time of the morning. :=\ The alarm (and supplied battery) were only installed about 6 months ago but the expiry date on the battery was March 2016 so it had probably been sitting in storage for quite some time before being installed.
Getting to the point, I'm about to buy some more. There are several types/brands available with different chemistries including Lithium Manganese Dioxide, Zinc Carbon, Zinc Chloride and Alkaline. Which should I be looking at for this application?
Each alarm is normally powered by mains power and the battery is only used during a power failure. Ideally it should be very low self-draining so that it lasts as long as possible. Also, I'm not sure what the "low battery" alarm trigger voltage is on these smoke alarms?
Any suggestions? Spare any Batteriser jokes please ;-)
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Zinc Chloride or Carbon batteries are crap, and tend to leak so should *NEVER* be used in a long duration critical application. Replaceable smoke alarm batteries should be changed annually, so simply fit a fresh leading brand Alkaline, and clean the alarm in accordance with its instructions at the same time.. If the battery expiry date isn't five years or more away it isn't fresh. Because of the need for regular cleaning and scheduled replacement there is no benefit in getting the vastly more expensive Lithium batteries.
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Use the lithium batteries and after a year put it in your DMM. :-DMM
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I just typically use Duracell or Energizer alkaline 9V standard batteries purchased from reputable stores (usually boxing day/week where I can get four for $6 CDN). They last over 1 year in my 9V powered smoke detectors (3 of them). I do a get a low battery warning beep around 7.2V. At 7.2V, they go into my Fluke 70 series meter and will probably last another 500 or 700 hours of use.
Typically, I change the batteries once a year regardless of their voltage.
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Sounds like you need a Batteroo/izer ;-)
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Thanks for the feedback guys. I just went with some Energiser 625mAh Alkalines.
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You probably need to get some more Fluke DMMs while you are about it, to use the retired batteries in...
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Energizers leaked on me a couple of times. Tend to go with GP Ultra now.
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This was two new batteries in low drain kit. Nearly destroyed my Fluke 77 and my CO detector.
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yeah, 9V Alkaline for smoke detectors, its the best value for money. (Other than duct taping a 6pack of AA's to it) :-DD
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You probably need to get some more Fluke DMMs while you are about it, to use the retired batteries in...
Or I can send them to Roohparvar for his scientific tests :P Further proof that people don't use all the capacity on their batteries ;-)
Interestingly the smoke alarms came with some cheap Chinese Zinc Carbon batteries. I guess they are the cheapest and they figure people were going to replace them soon after purchase anyway.