Taking
the information we have already gathered during the baseline battery
tests, we can graph the relationship between voltage and SOC under
a 70 amp load for some randomly selected batteries.
For
this graph, we use actual achieved capacity rather than rated capacity.
Notice
that the curve of the graph of cell #74 matches the other 4 cells
fairly closely but .02 volts lower. To check this anomaly, we graphed
cells #73 and #75. Since their graphs match the other cells, it
is unlikely there was a change in test equipment. Cell #74 test
temperature and actual capacity is also within the range displayed
by the other cells.
Out
of curiosity, we add cell #77. This cell was one of the ones that
charged in an aberrant fashion. Hitting 4.2 volts after only 50
amphrs rather than the 60 amphrs that was the norm for 90% of
the batteries. #77 and #74 match fairly closely. Why do they both
sag more under load than other batteries?
The
Excel file can be downloaded by clicking the link below.
file

description


Zipped Microsoft Excel file with data and charts for 70 amp
discharge to voltage study. 
