@Ezdong
Cách đo đây nè anh này
Step 1 - Loosen the negative battery terminal, but do not disconnect it yet.
Step 2 - Prepare the meter for the in-line current measurement by inserting the RED probe in the “A” jack and the BLACK probe in the COM jack. Turn the measurement selector dial to the “A” position. (Caution - do not take a voltage measurement while the meter probes are configured in this position. Doing so can
damage the meter)
Step 3 - Secure the RED probe on the negative battery terminal before removal so you will not need to hold the probe with your hand. Often an alligator clip or jaw” type probe accessory is ideal for this procedure.
Use the following guidelines to assess and troubleshoot the vehicle’s stand-by current drain.
0-15 mA (0.000-0.015A) - This is a normal reading. If the battery is having problems, check the age and state of charge. It may be time to replace this battery simply from age or normal wear and tear.
16-24 mA (0.016-0.024A) - This is outside the normal range, but is not excessive. Check to see that all security and remote starter power and ground connections are functioning properly. Ensure the battery is charging properly and has a good state of charge.
Over 25 mA (>0.025A) - This is beyond what is considered acceptable. Start pulling fuses or disconnecting power of aftermarket accessories to see if the drain goes away. If still present after this, proceed to pulling OEM fuses. This method is the most effective way of determining the offending excess current drain. Once located, repair the problem and re-check.
Step 4 - With the red probe secured on its own, hold the BLACK probe tip near the base of the battery post so it does not interfere with the terminal. The object will be to remove the terminal without having to move or reconfigure the BLACK probe.
Step 5 - With your free hand, remove the negative battery terminal while holding the BLACK probe in position on the battery post with your other hand. You should now be able to read a measurement.