Forest, Come on
Barry, Will you do me a favor. For PS-2 Disconnect a battery from an engine and then do the battery test. You will see high. The reason is the voltage is 5VDC at the charge port. Even though there is no battery charging.
Place a battery back in and you would read about 2.5V and get a Normal with a battery test.
Place an uncharged BCR in the port and run the test and you would get low, as the BCR drags the voltage down starting at a few mV as it charges. Once it gets to 2.5V it would be normal and as the BCR completes the charge it sits at 5VDC and would read high.
The Battery test is really a health of the whole battery back up system. It does this by measuring voltage not current flow. Low or High can mean different things. A shorted battery would cause a low. No battery a high, normal battery normal. A failure of the battery cutoff circuit or the trickle charge circuit can also cause low or high readings.
In most cases, a LOW reading from a dead battery with no voltage which would drag down the buck voltage that normally sits at 5V at the battery terminal.
A new battery fully charged battery would not read LOW ( not needing a charge or low trickle charge as you stated). It would read normal. If you put a good but discharged battery (resembles a BCR) then it would read low, even though we know the battery is getting a maximum charge. G