Lewis,
Some ammeters can measure only DC. Others can measure AC and DC. But we are only considering battery chargers, which are direct current, so we can focus on the DC ammeter, of which there are several types (look on Wikipedia). They should all indicate the correct current, regardless of what type of load you are measuring. Remember, measuing current is like measuring the flow of water. Your water meter measures every gallon, regardless of whether you are watering the lawn, flushing the commode, or filling an ice cube tray.
Perry,
When I saw you in Erie, you were just a regular guy (albeit with a nice No. 4 skillet and lid). Are you saying that you are now like a bumblebee and capable of flight? Even though "science" says it is impossible? ;D