My reasoning for removing both cables is that I once witnessed the aftermath of did happen when the negative cable isn't "secured" in such a manner that it doesn't accidently make contact with its battery terminal during the charge.
What the gent came back to a few hours later was a cracked battery case, battery acid in the engine compartment, on the fender and bumper. Needless to say, a mess. The negative cable was found in contact with the terminal.
The ground cable found its way back to the negative terminal. I suspect the cable insulation's memory on that cold day caused it. The spark must have fired off the hydrogen sulfide gas in the battery. But of course, it could have been charging a very bad battery.
So unless I can secure the ground cable well. I just spend a few more minutes pulling the postive and go ahead and give everything a good cleaning and a coat of vaseline.
Thanks for posting. My curiosity in this area far and away exceeds my expertise, so I spend a few dollars here and there for books and manuals and try to get smarter.
With the "GEN" lamp in the preexcitation circuit, is it possible that the preexcitation occurs (which will turn the "GEN" light out), but that the excitation circuit hangs up. When I read Bosch's Technical Instruction book on alternators, there is some discussion regarding post preexcitation where residual magnetism aided by preexcitation, induces a slight voltage into the stator winding. This causes a small flow of current in the rotor winding which finds its way back to the stator, and this process repeats itself until the alternator is fully excited and desired voltage level is increased. Any thoughts on what would account for the odd behavior mine exhibits (will not generate proper voltage without first throttle engine rpm past about 2000)? I'm fairly certain that is is not a battery issue as this is the vehicle's second battery (4 years old) and this behavior was identical with the previous battery.
S, J.R. Brown
2000 G500 LWB Obsedian Black
2005 Toyota Tacoma Access Cab Off Road Sport
1993 Volvo 240 Sedan Anthracite
1980 450SEL Champange (owned it for 15 years. Great car)
1986 280GE LWB Anthracite (Sold it and kinda wish I hadn't)