The front door bell push on my *wireless* doorchimes (made by Byron) has a small 12 volt A23S battery in it.
The chimes have stopped working, and i've tested the AA batteries in the chime unit and they are all alright.
Is there any simple way to test the 12 volt battery in the door push? I have a simple cheap voltmeter, but am not sure how to best test the battery with it.
On Tuesday 19 November 2013 10:33 r brooks wrote in uk.d-i-y:
Test it in place is possible and push the button. If it holds at 12V it is fine.
Remove battery Set meter to volts DC Attach leads
Preferably using a cheap and cheerful 1kohm/ volt moving coil meter. Or test it in circuit while pushing the button, as a flat battery may well show 12 volts or so when open circuit (As is the case when using a digital meter), but drop to near zero when under load. You can also buy specialised battery test meters, Or just buy a new battery and replace it. They're not *that* expensive....
Yes, good point about testing under load.
Where can one find such meters, as a matter of interest?
Really? One which worked ok previously?
I'm not disputing the best test is a load one, though.
Depending on what you want Rapid has a selection:
You pay more for a smart one that recognises the battery chemistry and internal resistance and deduces residual capacity more accurately.
Simple go no go one is a load resistor and a means to measure voltage.
For most primary cells a dead battery is usually well below 1v per cell where a live one is over 1.2v so if you 12v nominal battery now reads
10v without any load it is definitely dead as a doornail. A fresh cell should be a nominal 1.5v (and 10% lower for NiMH and NiCad)In high current circuits it is the terminal voltage with the load applied that matters. I doubt if a wireless doorbell transmitter draws all that much current so probably not that important here.
. . . provided the pushbutton is subjecting it to a load. If there's a discontinuity in the circuit, it might not be.
I think I would want to see the voltage drop a bit when the button is pressed - but not too much - maybe half a volt or so.
Leave it measuring as you press the push, if the voltage dips its died. Brian
Of course many of these also have an led that comes on. If this does not light either it may well be that there is corrosion on the battery connections rather than a duff battery. Brian
I have had some of these wireless bell pushes die due to broken switches or inoperative switches, which is not quite the same. One of these seemed to rely on soem conductive foam that was pushed down to short out two tracks on the pcb, but the foam perished, in another case the switch itself was mounted on what looked like heat glue and had broken off due to a kung fu bell push adict. Brian
I must admit I hate wireless doorbells. Of course they have their uses but if you can fit a wired one, do so. So much less aggro when it comes to trouble shooting.
Tim
Ideally, yes, but you can still often get a good idea by simply checking the open circuit voltage. If it's like 10v or less, you need a new battery anyway.
+1
My mate has one. When I visit him, I knock the door, because it works only intermittently. My neighbour has one. It is triggered by my car remote lock "plipper". He loves it when I come home at 2 or 3 in the morning and lock the car remotely!
Measuring voltage offload is usually enough. Once its down from 1.5v to 1.3v its near end of life, appliancse vary in how low they can go. No way would I consider a 1.2v cell ok for anything except the occasional clock that might tolerate that.
1.5v-> 1.3v : 12v-> 10.4vYou can measure voltage under load for more accuracy, but its usually not necessary.
NT
Don't bother with the battery, remove it, run a bit of 2 core wire to the bell push from inside the house, connect the wire to the contacts where the battery went, and inside the house connect the wire to a 12 volt wall wart, never need to worry about the bell push battery dying again :)
If you can get a wire to it you don't need a fecking dodgy wireless doorbell at all! ;-)
Tim
Quite. A decent quality transformer fed cabled bell and push will last a lifetime - as well as being louder. I've never quite understood why someone will re-wire an entire house but not include this.
Even a battery one can last a year or two. When we moved into our current house about 15 years ago, the door chime contained two rather ancient looking Eveready HP2s.
They only lasted another ten years before expiring. Given that the batteries probably date from the 70/80s, that's not a bad lifespan. ;-)
Tim
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