When choosing a lithium battery for testing instruments, the following aspects need to be considered:

1. Battery capacity: Select the appropriate battery capacity according to the power consumption and usage time requirements of the testing instrument. Generally speaking, the larger the capacity, the longer the use time, but it will also increase the weight and volume of the battery.

2. Battery size and shape: Choose the size and shape of the battery that matches the instrument to ensure that the battery can be installed correctly and meet the power needs of the instrument.

3. Battery type: There are many types of lithium batteries, such as lithium-ion batteries, lithium polymer batteries, etc. Different types of batteries have different advantages and disadvantages, which need to be selected according to actual needs.

4. Safety: Select high-safety batteries to ensure safe use. You can view the safety certification information of the battery, such as UN38.3, etc.

5. Brand and quality: Choose a well-known brand and high-quality battery to ensure performance and stability.