How to test a watch battery with a multimeter (guide)
Content
Small watch batteries, also known as button batteries, and small single-cell batteries can be used with a variety of electronics. You can find these round batteries on watches, toys, calculators, remote controls, and even desktop computer motherboards. Commonly known as types of coins or buttons. Usually, a coin cell battery is smaller than a coin cell battery. Regardless of the size or type, you may need to check your watch's battery voltage.
So, today I'm going to teach you how to test your watch battery with a multimeter.
In general, to check battery voltage, first set your multimeter to the DC voltage setting. Place the red multimeter lead on the positive battery post. Then place the black wire on the negative side of the battery. If the battery is fully charged, the multimeter will read close to 3V.
Different battery voltages for watches
There are three different types of watch batteries available on the market. They have a different type of voltage, and the size is also different. These variants can be identified as coin or button type batteries. So here are the voltages of these three batteries.
| Battery Type | Initial voltage | Battery replacement voltage |
| Lithium | 3.0V | 2.8V |
| Silver oxide | 1.5V | 1.2V |
| Alkaline | 1.5V | 1.0V |
Keep in mind: According to the above table, when the lithium battery reaches 2.8V, it should be replaced. However, this theory does not apply to the conventional Renata 751 lithium battery. It has an initial voltage of 2V.
What you need to know before testing
In this section, you will be able to learn two methods for checking battery voltage.
- Initial testing
- Load testing
Initial testing is a quick and easy way to check your watch's battery voltage. But when testing under load, you can observe how a particular battery reacts to the load.
In this case, a load of 4.7 kΩ will be applied to the battery. This load may vary depending on the type and size of the battery. Select the load according to the discharge characteristics of the battery. (1)
What do you need
- Digital multimeter
- Variable resistance box
- Set of red and black connectors
Method 1 - Initial Testing
This is a simple three-step testing process that only requires a multimeter. So let's get started.
Step 1. Set up your multimeter
First of all, set the multimeter to DC voltage settings. To do this, turn the dial to the letter V.DC symbol.
Step 2 - Placing Leads
Then connect the red lead of the multimeter to the positive battery post. Then connect the black wire to the negative pole of the battery.
Identifying the pros and cons of a watch battery
Most watch batteries should have a smooth side. This is the negative side.
The other side displays a plus sign. This is a plus.
Step 3 - Reading Comprehension
Now check the reading. For this demo, we are using a lithium battery. So the reading should be close to 3V considering the battery is fully charged. If the reading is below 2.8V, you may need to replace the battery.
Method 2 - Load Testing
This test is slightly different from the previous tests. Here you will need to use a variable resistance block, red and black connectors and a multimeter. As mentioned earlier, in this test we apply 4.7 kΩ with a variable resistance block.
Tip: A variable resistance box is capable of providing a fixed resistance to any circuit or electrical element. The resistance level can be in the range from 100 Ohm to 470 kOhm.
Step 1 - Set up your multimeter
First, set the multimeter to the DC voltage settings.
Step 2. Connect the variable resistance block to the multimeter.
Now use the red and black connectors to connect the multimeter and variable resistance unit.
Step 3 - Install the Resistance
Then set the variable resistance unit to 4.7 kΩ. As mentioned earlier, this level of resistance can vary depending on the type and size of the watch battery.
Step 4 - Placing Leads
Then connect the red wire of the resistance unit to the positive post of the watch battery. Connect the black wire of the resistance unit to the negative battery post.
Step 5 - Reading Comprehension
Finally, it's time to check the evidence. If the reading is close to 3V, the battery is good. If the reading is below 2.8V, the battery is bad.
Keep in mind: You can apply the same process to a silver oxide or alkaline battery without too much trouble. But remember that the initial voltage of silver oxide and alkaline batteries is different from the one shown above.
Summing up
Regardless of battery type or size, always remember to test voltage according to the testing processes above. When you test a battery with a load, it gives a good idea of how a particular battery responds to a load. Thus, this is a great way to identify good watch batteries. (2)
Take a look at some of our articles below.
- How to check the battery with a multimeter
- 9V multimeter test.
- How to use a multimeter to check the voltage of live wires
Recommendations
(1) battery – https://www.britannica.com/technology/battery-electronics
(2) good watches - https://www.gq.com/story/best-watch-brands
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