[AT] JD 620 / charging six-volt batteries

[Dean Vinson]

When charging either of the two six-volt batteries in my 620, do I need to
worry about disconnecting them from each other?   

http://www.vinsonfarm.net/photos/620_batteries_20140703.jpg

They're wired in series to provide 12 volts to the starter, so the (-)
terminal of the grounded battery is directly connected to the (+) terminal
of the other battery.   Hooking the (-) clamp from the charger onto the (-)
post on the grounded battery (good) is therefore electrically the same as
hooking it to the (+) post on the other battery (bad).  So I've been
disconnecting that big jumper cable between the two batteries.

But as I think about it, it shouldn't make any difference unless there's
some path by which the charging current is being applied to the other
terminal of the second battery also.  Correct?  No complete circuit to that
battery, no effect of touching only one of the posts?

Thanks--

Dean Vinson
Saint Paris, Ohio