[Kevin Sevcik]

Originally Posted by techhelpbb

Some ideas off hand...

1. Close a relay contact over the circuit and hope they really have a circuit breaker up the path of current to the battery. You can do this because you'd have power from the bridge rectifier on the logic side. Could be too slow, but remember these diodes do take large surges during field collapse anyway...you do have a little time.

2. Rig a capacitor circuit to charge it's way up and reduce the voltage differential (it's not AC it won't discharge). Just make sure you check with the Stellaris if the power is backwards before you start switching. Probably have to make this component exit from the circuit with a small relay as well in the proper polarity.

3. Use fast blow fuse not these thermal breakers and make it easy to replace.

No matter what the H-Bridge will not be operational with the power reversed but I think it should be possible to give it enough protection to survive a minor error.

You're over-complicating things. If you're already willing to go to the trouble and expense of tossing a relay into the circuit, then you simply use the relay to energize the power stage. Heck, with a double throw relay, you could have the relay swap your polarity on the power stage for you. Your only problem is that you need a relay that can handle 40A continuous. Those relays aren't small or cheap.

The better open would be a standard mosfet based pass-protection eric described, which I'm pretty sure is already too expensive for the product.