I've had a second battery for a while now but was never too happy with the hookup. First I had an isolator but didn't like the diode drop, then I got one of those marine battery manual switches and mounted it under the hood. When I got a 130 amp alternator I finally got it right when I purchased an add on 250 amp solenoid from Painless Wiring. Now all I have to do is flip a switch on the dash to charge the second battery or leave it isolated. With the add on solenoid they just supply mounting hardware and some crimps with it, but that's all I really wanted in the first place, not all the wiring and the switch. I just wanted to let everybody know you can buy them separately.