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[TakeTheActive]

Originally posted by Nathan on Fri, Jan 28, 2005 @ 4:08 pm in the Home Automated Living Forums
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Their life is hard to predict. I have some that last months, and some that last a few weeks. And in fact it doesn't seem to be all that related to traffic patterns sometimes. I have had new batteries die within two weeks, and then their identical replacements last 3 months in the same service.

I find that in really heavy use areas, such as the living room, Alkalines work best, and last about a month. In low use areas, Alkalines will "die" in a couple of months, at which point I have to take them out, clean the terminals and replace them in the Hawkeye, after which they are good for another two months or so at which point the process is repeated again. If I have the patience to service them regularly, the Alkalines will last up to 8 or 9 months in low use areas, maybe more. Heavy-Duty batteries will last six months or so in the same service and do not require any attention until they die.

One variable is the quality of the battery, and another is the quality of the connection. In particular, long-life alkaline batteries seem to "false-fail" in that they will appear to die, but you take the batteries out and test them and they are fine. Put them back in and they work like new again. I believe this is related to their alkaline chemical composition and an invisible film that seems to develop on their terminals when they are relatively unused. I have seen this phenomenon in flashlights with Alaklines, where they lie in the drawer for months and then won't work when you want them. Cleaning the battery terminals seems to restore service.

I have also noticed that devices with gold-plated contacts do not seem to experience this failure. Perhaps just the better quality of the contacts prevents the issue.

Lately I have taken to placing a thin layer of a silicon lube on the terminals of the batteries to see if that prevents the premature failures. The Hawkeye that senses when I am at my desk (and sees several events per minute when I am working) has been running nearly a year on Alaklines which I gave this treatment to. Looks very promising.

In a couple of places where I need extra reliability and cannot afford to service frequently, I have attached an external battery pack with 2 HD AA batteries. Double A's have a lot more capacity than triple A's, and I have yet to replace a pair of AA's running a Hawkeye. One is over two years old and still going strong.

So, my advice is as follows:

(1) Low use areas, use inexpensive Heavy-Duty batteries.

(2) High and moderate use areas, use Alkalines, but get some conductive silicon gel and coat a thin layer on the terminals to ensure the best corrosion proof, gas-tight connection.

(3) High Use and High reliability areas, especially if the cosmetics are secondary, go to radio shack and buy a two AA battery holder and place two H-D AA's in it, wired to the Hawkeye Battery holder. Weather proof as required.

Finally, I placed some rules in HAL to count signals from the various Hawkeyes, and track usage. If a Hawkeye is silent for 24 hours (or any reasonable timeframe) flag it as an error and have HAL set a reminder to check the batteries. This way, when a sensor does die, it will not go unnoticed long.

Good Hunting,
Nathan

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X10 Wireless Motion Detectors' Battery Life

[dave w]

Not meaning to take any thunder from Nathans suggestion of AA battery holders, I it to the next level.
A 2 "D" size battery holder is almost exact same size ( H & W) as Active Eye, Hawk Eye, etc series of motion detectors. Glue a 2 D battery holder on the back of Active Eye. The added weight acts as a great ballast so I can "plop" "an Eye" on any shelf, flat surface, floor, etc. Stick on rubber feet allow me add tilt if needed. I get better than a year out of the D cells.
FWIW

[Brian H]

I have seen messages that in cold areas and extended life. Lithium's are best though expensive.

[steven r]

I've also heard of someone that wired an AC adapter to one. Prehaps if power was nearby and the sensor was mounted in a hard to access area it could be practical. Personally I think that's more trouble than it's worth for 99% of all applications.