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I have just changed the battery on this one and its a Renata 373 , how long do these last ?, if forgot when i did the last battery change, any help on this would be a appreciated :)

 

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I have just changed the battery on this one and its a Renata 373 , how long do these last ?, if forgot when i did the last battery change, any help on this would be a appreciated :)

Not sure about the battery but that is a great looking watch if you don’t mind me saying. It’s been a long time since I’ve seen one of those. Especially in such great shape.
 

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When I change a battery I write the date on a small piece of tape stuck to the inside caseback so I can keep track of battery life. If you're asking about the life on a Renata, for me the major brands, Renata, Energizer, Duracell, Panasonic, Maxell, etc. all seem to last the same amount of time. Try to buy from a vendor that has a lot of turnover so you get a fresh battery. You don't want a battery that was sitting on a shelf a year (or more!) before you install it.
 

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Not sure about the battery but that is a great looking watch if you don’t mind me saying. It’s been a long time since I’ve seen one of those. Especially in such great shape.
Its been very well looked after :)
 

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This should have a Cal. 1438 inside, unless the movement has been replaced at some point.

This is an older movement, and some of these still had trimmers on them to adjust the timekeeping, but the latter versions didn't. This movement was eventually replaced by the 1538.

In terms of battery life, if this is an older 1438, then it will not be equipped with the technology to extend battery life. In older watches, the pulse of the motor will be one long pulse. In more modern quartz watches, the motor pulse is chopped, so the motor turns on and off several times during the pulse.

Here is a pulse graph of a traditional "older" quartz movement:



You can see that the motor is on the entire width of the pulse, which is 7.8 ms. This is a pulse graph of a modern quartz movement:



You can see that the pulse is chopped, so the motor turns on and off several times. The pulse width is the same, but the motor is only on 1/2 the time it is on the older movement - this is shown by the drive level percentage.

This technology allows the watch to run longer on a battery. It also incorporates feed back. In an older watch the motor pulses and the watch simply assumes that the hand has moved. In a modern watch, the pulse happens and the circuit looks for a signal that is generated by the hand stopping, then wiggling a bit from the inertia of the move. This signal confirms to the circuit that the hand actually moved, so it of so it keeps the drive level at 50%. If for some reason the hands doesn't move (for example a small particle in the wheel train) it will increase the drive level as needed to drive the wheel train through that blockage, and after a period lower the drive level back down.

This technology has increased battery life from the typical 2-3 years, to sometimes 4 or 5.

Cheers, Al
 

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2 - 3 years will suit me :)
In the end, it really depends on the condition of the movement, and how much current it is drawing. Since you simply changed the battery, and I assume did not tests on the movement (this requires specialized equipment) then there's no way to know how long the battery will actually last.

Although changing a battery yourself is cheaper than taking it to an actual watchmaker, it isn't really the same thing as a watchmaker does. Any good watchmaker will be performing a series of electrical tests on the movement to ensure it's operating properly, will change the seals, and provide pressure testing.
 

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In the end, it really depends on the condition of the movement, and how much current it is drawing. Since you simply changed the battery, and I assume did not tests on the movement (this requires specialized equipment) then there's no way to know how long the battery will actually last.

Although changing a battery yourself is cheaper than taking it to an actual watchmaker, it isn't really the same thing as a watchmaker does. Any good watchmaker will be performing a series of electrical tests on the movement to ensure it's operating properly, will change the seals, and provide pressure testing.
Il let my watchmaker check it out.
 
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