9 Volt Batteries

Batteries and Chargers Consumable Batteries
1

I recently had a smoke detector start to indicate that the 9 volt battery was low. I pulled the battery and used my DMM to measure 8.74v’s. Would that be low enough to set off a smoke detector for a low battery warning? (.26v’s)? I expected to see the battery somewhere around 3 volts. I was shocked. Any insight? Thank you in advance for your help.

RI Chevy

2

You are measuring the cell with no load. I don’t know how much load a smoke detector will put on a cell, but a load will decrease the voltage available.
Also, these smoke detectors have a life span of about 10 years, after which the detecting element has lost its pizzazz.

3

Under a load it would be less depending on how much current is being drawn. My opinion is replace the battery to be safe...

4

Thanks. I actually replaced the hard wired smoke detectors about 3 years ago. I already went ahead and replaced the batteries.

5

Energizer Lithium batteries are also available as 9V blocks, these would probably be better for such a long life application.

6

Thanks you. I’ll check for them and see if I can find them.

7

I’m sure that it’s similar to a AA battery. (Aren’t 9v just like 4 aaaa batteries?) If you measure a fresh AA, it’ll probably be a little over 1.5 volts at maybe 1.6 or 1.55 on the low end, and totally dead(doesn’t even work in a tv remote) is around .9 volts.

8

I only seem to get a year out of mine and they always start beeping in the middle of the night

9

I use the lithium 9V ones in my detectors… they last for years. I replace them every few years and use the old ones in multi-meters. My house has over 6 detectors…

10

I never change them until they beep….I’ve also found that they start to complain at about 8.7 v. I suspect the smoke detector people probably have a vested interest in the battery industry…… :stuck_out_tongue:
Once they beep, I set them aside and get plenty of life out of them in DMMs and the like.

11

Mine went off at around 3:00 AM. :smiley: Thanks for the replies guys. I just wasn’t sure about losing only .25v’s on a 9v battery and having to get rid of the battery. Looks like I need to buy a 9v paklight to get the max out of these 9v batteries. :wink: I am going to try the lithiums this time around.

12

The lithium 9v batteries have a higher nominal voltage (9.6 compared to 9) and should last a lot longer as it has more than double the capacity of the alkalines.