This item is available from a few companies, but I pulled this one from the West Marine site.
It automatically disconnects the battery when it drops just below 12v and reconnects the battery after the boatstarts...
http://www.westmarine.com/images/full/34430_f.jpg
It's 80.00 at west, but I've seen them for close to 50.00... i just can't remember where :220v:
You can run your perko and put this inline with your starting battery...
There is one on EBAY right now for 65.00 bucks. Another guy has them for 74.00 on ebay as well.
Eric
I say stick with a Perko, that way if there are any problems it's easily remedied. I have also seen isolators go bad, but I have yet to see a Perko go bad. It only takes one time forgetting to set the Perko in the right position, and it wont happen again.As far as remembering where the Perko is swiched to, thats not hard, clockwise: off, 1, both, 2.