Regulator question

[snakeyes146]

OK, here is what I have: 1999 Yamaha 100 outboard and I'm installing dual batteries with a solid state isolator. My question is this. I need to connect something to the "alternator" terminal on the isolator, but when I connect the RED +12Vdc wire from the starter solenoid, my ignition switching fails (instruments, trim functions, stereo, etc....) I disconnected the isolator for safety reasons and connected the RED lead back up to the original configuration and all is well. Should I simply leave this wire connected and add another on the same stud of the starter solenoid and run it to the alternator post on the isolator?? I don't see any other charging lead coming from the regulator/rectifier. Any suggestions would be appreciated.