Watch batteries, also termed as button cells, are an essential element of wristwatches that use Quartz movement. They are the main source of power supply to enable these classic movements to show accurate time. Most of the watch owners often wonder about its battery’s size, so in this blog, we will have a thorough look at its various parameters.

Different wrist watch models have different battery sizes. They are available in a cylindrical shape with a diameter ranging from 5 to 25 mm and height between 1 to 6 mm.  The chemistry types of wristwatch batteries can be alkaline, silver-oxide, zinc air or mercury-oxide.

The International standard IEC 60086-3 develops codes for individual batteries, which denote their chemistry, shape and size. These codes are a combination of alphabets and numbers. Proper understanding of these codes is essential for correct battery replacement.

Do Most Watches Use the Same Battery?

Each watch model has a specific battery size and type, and you can’t replace it with another one. However, if you can’t find your required one in the watch repair shops or stores, then consult multiple battery conversion charts available on the internet. They will help you in finding an alternative option which would function just as good as the old one.

One of the major difference between the watch batteries is their chemistry. The most commonly used ones are alkaline, silver-oxide, zinc air and mercury-oxide. Let’s have a look at their individual specifications:

Alkaline

• Alkaline batteries have a voltage of 1.5V.
• Observations show that their voltage drops over the span of usage.
• Their capacity ranges from 15 to 17mAh.

Silver-Oxide:

• Silver-oxide batteries have a voltage of 1.55V.
• They have a constant voltage.
• Their capacity ranges from 25mAh to 27mAh.

Zinc Air

• Zinc air batteries’ voltage ranges from 1.4V to 1.45V.
• They have low voltage and higher capacity as compared to other chemistries. As a result, they are rarely used in wristwatches and mostly in hearing aids.

Mercury-Oxide

• Mercury-oxide batteries have a voltage of 1.35V.
• These batteries have the lowest voltage among their counterparts. Furthermore, they aren’t in use anymore because of the environmental hazard imposed by their mercury content.

How Do I Know What Battery My Watch Needs?

In order to know which battery your watch needs, you’ll have to find its alphanumeric code. Sometimes, the manufacturers encrypt it on the back of the watch. You can also find it in your watch’s manual. In other cases, you’ll need to open its backside and read the code present on the battery.

There are various standards that develop the alphanumeric code present on the batteries. The most prominent ones among them are the International Electrotechnical Commission (IEC) and the American National Standards Institute (ANSI)

Now, let’s have a look at how we can understand a button cell’s chemistry, shape, diameter and height through its alphanumeric code.

• The first alphabet indicates the battery’s chemistry. S means silver-oxide, L means alkaline, C  means lithium, AG could be either silver-oxide or alkaline.
• The second alphabet indicates the shape of the battery. R means round, F means flat, S means square and P means not round.
• The first number is the battery’s diameter in mm.
• The second number is the battery’s height in mm.
• If there’s a W in the code, then this means that the battery is compliant with the international IEC 60086-3 standards.

How Often Should I Change my Watch Battery?

Battery replacement depends upon the watch’s age and quality. Watch experts suggest, if you have a new watch with the manufacturer’s original battery, then replace it after three years. Whereas, if your watch has a replaced battery, then change it every year for superior performance.

Let’s have a look at how you can open your watch’s case, and replace its battery in a few simple steps:

• Take a knife, and insert it in the gap between the back and other parts of the watch.
• Move it slowly along the edges to separate the back from other parts.
• If your watch has screws, then use a jewelry screwdriver to open them.
• Once its back is open, remove the battery and read the alphanumeric code written on it.
• Place the new battery such that the positive terminal is on the positive side of the watch, and the negative terminal is on the negative side. Mistakes in watch’s polarity can have a negative impact on the watch’s movement to the extent that they might become unrepairable.

While performing this simple procedure, make sure that you take care of these precautions:

• Avoid pressing the knife into the watch while opening the back as it might slip and hurt your hand.
• In case of a waterproof watch, take special care in removing and inserting the gasket. Improper insertion might damage this unreplaceable part.
• Make sure that you place the positive terminal of the battery on the positive mark and vice versa. Wristwatches don’t handle wrong placement well.

In case of luxury or expensive watch, it is better to consult a repair shop for battery replacement.

How Long A Watch Battery Should Last?

The age of a battery depends upon the watch’s quality, its functions and the frequency of functions’ usage. A new watch’s battery lasts for 4 years; whereas, a replaced one lasts between 1 to 2 years. Experts suggest that you should change a replaced battery each year to avoid leakage.

As mentioned earlier, battery drainage depends upon the watch’s function. If you have a simple Quartz watch with just the typical date and time functions, then your battery will last longer. However, if you have a more advanced watch with chronographs and other such high-tech features, then the battery will drain at a faster rate. Sometimes, these advanced watches have two batteries to fulfill their various functions’ power requirement.

Let’s have a look at some of the signs which indicate that your watch’s battery is dying:

• Watch has stopped working.
• Watch’s second-hand jumps at an interval of 5 seconds.
• There is a presence of moisture underneath the watch’s glass.
• It gets difficult to adjust the date or time through the crown.
• Watch stops showing accurate time.

If any of these issues pertain after battery replacement, then we suggest you consult a battery repair shop to find the exact fault. Most of the time, a malfunctioned movement is the culprit behind these problems.

What are the Best Watch Batteries?

The top 5 best batteries available on Amazon are:

1. Eunicell 100 X AG4 LR626 377 SR626 606
2. Maxell SR626SW 377 Silver-Oxide Watch Batteries
3. 100 pcs Assorted Exell Silver-Oxide Watch Batteries
4. AG4/ 377A/ 626A/ CX66W 1.55V Alkaline Watch Battery
5. AG4 377A 377 LR626 SR626SW SR66 LR66 376 1.5 Alkaline Battery

1.      Eunicell 100 X AG4 LR626 377 SR626 606

This product contains 100 AG4 Alkaline batteries manufactured by Eunicell. It consists of 10 packets, in which each one has 10 batteries. The manufacturer has sealed the batteries separately for your convenience.

AG4 batteries are also termed as LR66, SR626, SR626W, G4, LR626, D376, D377, 376 and 377. Pop open your wristwatch’s backside, as explained above, to find out your battery’s type and size, and determine whether any of these are a good fit or not. 

These batteries’ usage is not just limited to wristwatches, you can also use it for other devices such as keyless entry systems, remote controls, PDAs etc.

Following are the major specifications of Eunicell 100 X AG4 LR626 377 SR626 606:

• It has an operating voltage of DC 1.5V.
• It has a capacity of 12mAh.
• The package dimensions are 9.1 x 8.2 x 0.5 inches.
• The batteries collectively weight 0.64 ounces.

2.      Maxell SR626SW 377 Silver-Oxide Watch Batteries

This product contains silver-oxide batteries manufactured by Maxell. The manufacturer has sealed each button cell separately so you can use one at a time. Their code is SR626SW, and you can use them as an alternative for 377.

The Maxell SR626SW 377 Silver-Oxide Watch Batteries are best-suited for analog watches, which are low drain devices. This means that they require less power over quite a long time. These batteries have a long lifetime of more than 5 years.

Silver-oxide batteries have almost double energy capacity as compared to alkaline ones because of their high-energy density and unit volume ratio. Following are the main specifications of Maxell SR626SW 377 batteries:

• It has an operating voltage of 1.55V.
• The package dimensions are 5.1 x 2 x 0.3 inches.
• The batteries collectively weight 0.16 ounces.
• These batteries have a diameter of 6.8 mm and a height of 2.6 mm.

3.      100 pcs Assorted Exell Silver-Oxide Watch Batteries

Are you tired of ordering batteries and paying countless shipping costs to get the perfect one for your favorite wristwatch? If yes, then we recommend you to try 100 pcs Assorted Exell Silver-Oxide Watch Batteries. As the name suggests, this pack contains 100 silver-oxide batteries of different shapes and sizes. These are:

• 379 (SG-0) S521S
• 364 (SG-1) S621S
• (SG-2) S726S
• 377 (SG-4) S626S
• 393 (SG-5) S754
• 371 (SG-6) S921
• 395 (SG-7) S926
• 389 (SG-10) S1131
• 362 (SG-11) S721
• 357 (SG-13) S1154

The package contains10 number of batteries of each of the abovementioned types. Following are the major advantages and specifications of the product:

• Silver-oxide batteries are better than Alkali ones.
• It contains 10 battery options, which makes it easier to choose the best-suited one.
• These button cells aren’t limited to wristwatches, you can also use them in calculators, cameras and other electronics.
• It has a shipping weight of 8 ounces.

4.      Insten SR521SW Silver-Oxide Batteries

This packet contains 10 individually packed cells. They have the alphanumeric code of SR521SW. These batteries have silver-oxide chemistry and are known for their combination of continuous voltage and high energy.

Like most of the button cells, these ones’ usage is also not limited to wristwatches. You can use them in a number of other electronics as well, such as calculators, thermometers and handheld games. In addition to this, they have an excellent shelf life, so they won’t lose their workability by staying in your drawer.  

Following are the few advantages and specs, which forced us to recommend these batteries:

• They have high resistance to temperature changes.
• They have an operating voltage of 1.5V.
• The package dimensions are 7.3 x 2.6 x 0.2 inches.
• The batteries collectively weight 0.8 ounces.

5.      Sixsons 10 Pcs AG7 Lithium Battery

We choose to recommend Sixsons AG7 Lithium Batteries because they are certified by Conformité Européenne (CE) and Restriction of Hazardous Substances (RoHS). These batteries have alkaline chemistry and high-temperature resistance. The packet contains 10 button cells.

The AG7 batteries’ energy density is high; whereas, the self-discharge is low. Although its resistance to temperature spikes and fluctuations is quite good, manufacturer suggests that you should keep it in a dark, dry and cool place.

Let’s have a look at their advantages and specifications:

• Each battery has a diameter of 9.5mm. 
• Their standard voltage is 1.55 V.
• Their short circuit current is 0.3A.
• Their standard load current is 0.3 A.

These are the top 5 watch batteries available on Amazon. We have compiled this list by thoroughly analyzing the reviews and the specifications. We hope that one of them is suitable for your favorite watch.

We are sure that by now, you have learnt quite a lot about wristwatch batteries, and it would be easier for you to replace your old one. However, make sure that you take the precautions mentioned in the above sections because even a minor mistake in this procedure could make your watch unrepairable. We don’t want our readers to lose their prized possession due to a mishandled battery replacement.