Should I check battery current by ammeter?
"Many people" are correct in this case.

The problem is that an ammeter has a very low internal resistance. (It is designed to measure the current with minimal loading effect on the load.) If you connect it across the terminals of a battery a large current will flow, limited only by the internal resistance of the battery and the meter - both of which will be low.







simulate this circuit &ndash; Schematic created using CircuitLab

Figure 1. The wrong way and the right way.

Instead, figure out what the battery should be able to supply, connect up a suitable load resistor or lamp which would draw that amount of current and measure the result.