Today i was working on a machine with 4 6v batteries connected in series.
It was in a building that was very dark and the batteries were covered in dirt and i briefly accidently fitted one of the batteries the wrong way around.
After i corrected the mistake i couldnt get 24v across the four batteries, only 18v, from wherever that battery was out of the voltmeter circuit. Yet the same battery measured 6v on the meter, and load tested ok.
Could the polarity have been reversed on that battery after connecting it the wrong way around?
If so, does charging the 4 batteries in series correct this reverse polarity.