Why won't a 1.5v watch movement work on a AA battery?

The little motorhome clock is just a watch movement and I'm sick of replacing the tiny battery so I wired an AA battery to it... And nothing, put the little cell back in and it works again

 

Why won't a 1.5v watch movement work on a AA battery?

Did you verify that the battery was making good contact?

 

Why won't a 1.5v watch movement work on a AA battery?

The little motorhome clock is just a watch movement and I'm sick of replacing the tiny battery so I wired an AA battery to it... And nothing, put the little cell back in and it works again

It could just be that the voltage is too low with an AA battery!
My partner has a speaking watch that has run for several years on a 3.2V CR2025 Lithium cell. About 6 months ago the hands stopped moving, but the speech section still worked perfectly. Then last week it finally stopped. When I measured the cell it was just above 3 Volts! Replacing it with a new one at 3.2V and it's back to working perfectly again!

 

Should work.
What was the original battery?

 

Why won't a 1.5v watch movement work on a AA battery?

Are you sure it's a 1.5V movement? Some watches use a 3V cell.

 

yup, most likely wrong voltage. check original coin cell battery specs. if it is 3 or 3.3V you will need two AA batteries in series since they are 1.5V each.

 

Why won't a 1.5v watch movement work on a AA battery?

The little motorhome clock is just a watch movement and I'm sick of replacing the tiny battery so I wired an AA battery to it... And nothing, put the little cell back in and it works again

What, exactly, is the "little cell" that was in it to begin with? My guess is that it was NOT a 1.5 V cell, but more likely a 3 V lithium cell.

 

Did you verify that the battery was making good contact?

Yes I soldered wires onto the connections.

The original cell is an LR626 (1.5v) just popped out and measured, it's 1.32v and the movement was still working

 

The original cell is an LR626 (1.5v) just popped out and measured, it's 1.32v and the movement was still working

What is the voltage from the AA battery?

 

What is the voltage from the AA battery?

Was a new one so something like 1.56v it was an alkaline one if that makes any difference?

 

I'll try again tomorrow with a different battery if there's no explanation.

 

Was a new one so something like 1.56v it was an alkaline one if that makes any difference?

The button battery doesn't have much capacity. Don't see why any primary AA wouldn't work.

 

I soldered wires onto the connections.

Are you sure it was the correct polarity?

 

Are you sure it was the correct polarity?

Yeah I think so, I remember checking how the cell sat in the holder and what polarity the tabs were. was a week ago now, I'll do it again tomorrow..

All this reminds me of a similar problem I had last year. I bought a little LCD digital thermometer to give me a reading inside the fridge. I cut a rectangular hole in the panel above the door and clicked it in, It had 2 x 1.5v button cells in parallel so in order not to be prising it out and changing them every 6 months I fitted an AA battery holder on top on the fridge and wired it into the contacts.. All worked perfectly for about a week, then it just went off, blank screen. I removed and tested the battery, all OK and just put it down to a faulty unit.

Ordered another one, fitted it on the AA battery holder, all worked perfect for a few days and then... You guessed it, it went off again. Suspecting the incompatibility of the battery and starting to lose the will, I put the 2 button cells back in and it's worked perfectly ever since

 

Yes I'm sure they were in parallel

 

Do you realise that the case of a button cell is the positive. The contact that connects the center of the cell is negaitive. This is opposite to AA cells.

Les.

 

Connected it up to an AAA battery this time and it's working
So I've no idea what the problem was. Going to leave it running for a few days now and see if it keeps time.
Thanks for your comments, gave me the inspiration to try again

 

Still suspect incorrect polarity.
But glad you got it working.

 

Clock stopped today, tested battery and it's flat.
Put a new one in and measured the drain, it's flashing between 0 and 1ma so maybe half a miliamp?

That van is haunted

 

Ordered a new clock £5.50
I might as well connect the AAA battery but it looks like I've found the reason the watch batteries didn't last. The movement has come to the end of it's natural life