In the repair of watches, one of the most common interventions is changing the battery, well because its load has run out or take too much time on the clock. But, have you ever wondered what’s inside a battery?
The batteries of silver oxide consist of several elements:
- An external, metal housing that contains all the others.
- A positive electrode of silver oxide.
- A zinc negative electrode.
- The electrolyte in the chemical reaction that allows the passage of electrons from one to the other electrode originates. Made of a dense gel containing potassium hydroxide or sodium hydroxide-based. It sits between the two electrodes.
- A Board that acts as an insulator between poles and at the same time retains the gel inside the housing.
There are many brands of batteries and very different prices, from 0.60 up to €20,00 approximately. This large difference is due to the quality of the elements forming it, the same freshness and size. Logically, a simple housing is cheaper than one consistent, but it is also weaker. Finest electrodes are cheaper than a few strong, but its duration is lower. With the Board happens something like: if it is straightforward or of low quality is cheaper, but less resistant.
Even if you call them colloquially button cell batteries, we must know that size is not the same for all, ranging between 4 and 11 mm in diameter, and between 1.25 and 5.4 mm in height, approximately.
Its rated voltage is 1.55 volts and its load capacity ranges from 8 to 160 milliamps per hour depending on the size and manufacturer.
Watches currently have a ridiculous consumption, between 0.0005 and 0.008 milliamp/hour, so the battery will remain for many months inside keeping it in operation. Manufacturers of watch movements, to design them, taking into account the consumption of the mechanism, and based on this provided him with a battery of the proper size so as to maintain it in operation at least for a period of twelve months without changing it. But this choice is always above the expected consumption and clock can operate several years without changing the element that gives you energy. And when it comes to mechanisms with several functions, if we do not use the extra we get longer battery life since we are not consuming the minimum expected.
From the moment in which they are manufactured, inside different processes arise, which are maximized when the consumption thereof, among others are in because clockwork oxidation and sulfation and as a result of the chemical reaction is heat generation that tends to blending the gel, making it more aggressive towards the housing and the Board that with the passing of the years just by corrode, allowing the exit of gel, and blending, and sulfates generated inside.
These chemical processes cause the batteries to become a component with expiration date. Even being stored they present a self-unloading estimated 10% per year, which in the five years we can consider them between useless and ten out of service. Given this, certain watches and other repair shops little scrupulous, fearing the possibility of having to dispose of them, offer them at lower price when they have more than four or five years.
We should also bear in mind that in circuits fed by continuous current provided by batteries or batteries, produces an effect of sulfation of the contacts. This is due to the internal reactions that occur in them, and it increases with the passage of time, resulting in corrosion of the contacts, reason why we must go to our regular watch repair center and request a change of battery, but follow the clock running.
From repair your watches , I recommend that you make changes in battery, and any other repair of watches, in workshops of confidence and Shun settlements with suspiciously low prices. Keep in mind that, to save a few euros you can damage important in your clock mechanism.