Well, I finally got my hands on the mobility scooter I posted about awhile back. As best I can make out, there are a couple of small wires with diodes that allow the unit to charge no matter what position the battery selector is in. I have batteries #1 and #4 as one 24 volt bank and batteries #2 and #3 as the other bank. I just had to work this out via common sense as the thing was a mess when I got it. It anyone has the time and knowledge to check my work, I sure would appreciate that. As it stands now, the speed controller is smoked, so I'm waiting on one of those to finish up. I can't really test the charging circuit as the batteries are all brand new and show full charge... once I can run the motor I'll know more but for now here is the circuit I came up with. Thanks in advance for any help or suggestions.