There's no way to know for your specific smoke detector.

Every six months, I break out the pulse-load battery tester (the one I like is http://www.batteryjunction.com/zts-mbt.html, no affiliation) and test the Energizer Lithium AAAs in my smoke detectors. If they don't all test at the same level, I replace them. If they test out at less than 60%, I replace them. Given that a smoke detector is good for ten years max, I end up replacing the batteries approximately twice before replacing the smoke detectors.

With alkalines my advice is to replace them every six months without bothering to test.

Most battery testers are just voltmeters, and don't test the batteries under load. In other words, most battery testers are next to useless.

If you have any doubt, replace the batteries.

Thanks Chaos!

This is Not a recommendation for anyone,& I advise against it!I have been out in the boonies more or less in the past,& Just didn't have my Multimeter handy(shucks! I alway's carry my multimeter on dayhikes/expeditions)I needed to check the load of a 9v battery,hello mr. tongue,whoa! spit a few times,Habanero pepper = Full Load,tested another,spit some more,Jalapeno pepper = 1/2 load,tested yet another,no spit required,Bell pepper = dead battery

The crazy thing about your reply Rich is that I understood it. lol

HJ

Very good point, however, if you cook like I do your smoke detector gets tested regularly. At least the one closest to the kitchen..............

Thanks for all the input. I decided to give these a try: http://www.ebay.com/itm/10-pcs-x-9-Volt-...#ht_3341wt_1342

To start off, I just want simple lights. Don't need waterproof. (Next round I might).

These have a low and high switch. They are a lot less expensive than the others so if the quality is good, they will do the intended job. I will give you a report when I get them.

I now am intrigued with the higher end ones, the encased waterproof ones. (It just never ends does it?!)

Craig T.

Those look like the same sold by DealExtreme.
http://www.dealextreme.com/p/9v-battery-...on-1-6f22-52813

Price is comparable, if not a little better.

I joined this forum just to answer your question. I just happened to be looking at those flashlights the other day and then saw your post. So here you go.
http://www.survival-warehouse.com/lighting/9v_lights.htm

Your username is humorous considering the Pak-Lites were referenced in the OPs first post.