I have an Accutire tire pressure meter with a "permanent battery". It is many years old and it began showing "L" instead of a reading. That means low battery. The package said to return it to the maker if the battery ever failed. Since the manufacturer appears to be defunct (although similar meters are still sold), and the thing was only $10 when new, I figured I would take it apart and see what this mysterious permanent battery was. The unit isn't hard to disassemble, and inside there was a bog standard CR2032. So I replaced that. That eliminated the "L". Now instead it briefly flashes a 188.8 display (typical sort of LED warm up display) and then shows "01.0". No matter what the pressure. A bit of googling turned up several other people who had had the same experience. This one posted a nice set of pictures, and circuit description, so I'm not going to bother posting my pictures too, as they look exactly the same.
http://jf64.wordpress.com/2010/10/24/pressure/
I don't think the "01.0" is a result of either the electronics having been blown up or an air leak. There is a little rubber seal, and while it might leak a little, the whole thing is quite tightly held together when the screws are in. It might leak a hair, but certainly not as much as the air that leaks out around the front when trying to make a seal to the tire stem. Rather I think there must be some sort of calibration step, or reset, not the "zeroing" the minimal instructions describe, to get the thing to work when a new battery is installed.
Anybody have a guess what it might be? I tried holding it onto an inflated tire for a long time (20 seconds) and for a short time (.3 seconds?) but neither did it.
http://jf64.wordpress.com/2010/10/24/pressure/
I don't think the "01.0" is a result of either the electronics having been blown up or an air leak. There is a little rubber seal, and while it might leak a little, the whole thing is quite tightly held together when the screws are in. It might leak a hair, but certainly not as much as the air that leaks out around the front when trying to make a seal to the tire stem. Rather I think there must be some sort of calibration step, or reset, not the "zeroing" the minimal instructions describe, to get the thing to work when a new battery is installed.
Anybody have a guess what it might be? I tried holding it onto an inflated tire for a long time (20 seconds) and for a short time (.3 seconds?) but neither did it.
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