* Current test: maximun olad:
    20a/48v dc for 10 seconds
    accuracy: +/-20% or 0.2 reading with a decimal point
* Voltage test:
    test range: 1-48v
    accuracy: +/-1%, or 0.1 reading with a decimal point
* The lcd indicates "err" condition:
    when the positive or negative pole is connected reversely
    the test voltage is less than 1v
* When conducting voltage test,the resistance between the
    measured object is less than 1k
* Pober supply: one aaa 1.5v battery(not included)