[ME_Andy]

Mmmm I like your intention to work on the Cruze but I think you're going about this the wrong way. The logic behind the alternator is actually pretty complicated, not just "ON if voltage falls below X." For example, the alternator is automatically ON if the headdlights are on. There was a thread about it on Cruzetalk a couple days ago.

I agree with ^, why do you need a clutch? I think a better way to go about it would be:
1. Replace the Pb-acid battery with lithium ion.
2. Replace your lights with LED.
3. Set up a system to plug in and charge your battery at home.
4. THEN, set up a switch to manually disable recharge while you're driving.

No clutch needed.