Hello, you can use voltammetry, use a lithium battery with a load and chain an ammeter in series. For example, if the current is 200 mA, 10 hours will equate to a capacity of 2000 mA. The current must remain unchanged during the measurement. . If the time does not reach one hour, use the measured time. The time is divided by 60 and multiplied by the measured current.
From: Xia Wanglin
Input voltage range: 9-16V
Standard input voltage: 12V
Starting current: 6.5 A< /p> p>
Normal operating current: 3.2 A
Constant output power: 35 W
Temperature operation: -40 degrees ---+105 degrees
Open circuit protection: Automatic protection after 0.5 seconds after open circuit
Short circuit protection: Protection automatic after 0.5 seconds after short circuit
Low voltage indicator: > 8.5 V Low voltage protection: < 7.5 V
High voltage lighting: <17V High voltage protection: >16V
20ah divided by 3.2ah, theoretical calculation can be used for 6.25 hours, because the starting current is large , actual usage should be around 5 hours.