Penny wise
Schottky is arguably overkill. Spending a lot of money for that half a volt is not warranted IMHO.
I would argue.
. Voltage drop is about 1.1 volts for the power P-N diodes (0.70 volt is drop for signal diode). The Schottky is about 0.20 volt, so the difference is almost a full volt, worst case.
An extra $20 going to kill you?
Aeroelectric recommend the cheap rectifier p-n diode block, which Radio Shack use to carry in store. Having 0.20 volt drop (Schottky) verse 1.1 volt drop (p-n junction rectifier diode) is worth extra nickles to me. Again its arguable. (The Radio Shack bridge in my junk drawer says 1.7 volt fwd volt drop! That's fine if you are running at 100 volts or 200 volts, 1.7 volts is not much.)
On a good day say your alternator supplies 14.3 volts at the main buss, so you will only have 13.2 volt for your essential buss? Now the scenario is your alternator dies, you're down to battery power (12-12.6 volts). Do you want another 1 volt drop? Some radios will not run on 11 volts. Aeroelectric says add a second switch & more wire for an aux circuit to power the essential buss directly from the battery, by-passing the main contactor/relay and diode. That will get the voltage back up but it's more complication.
How about not having a diode or switch bypass for the essential buss at all! If you want to "shed load", manually turn items off or pull CB's (yes I have pull-able CB's). Aeroelectric loves fuses of course, and if you use CB's the terrorist will win, I'm told.
(its a joke)
If you want an isolated and have alternative power to the essential buss, you could use two switches, one to isolate and one by-pass direct battery power, no diode. You just need to remember the sequince of switch thowing, MAKE before you BREAK the connection.
The claim to fame of the
"25A, 50V Full-Wave Bridge Rectifiers" was you could walk down to Radio Shack and buy one for $4. I was told they don't carry them in store any more, avaiable only on-line now.
I can see where $4 does sound better than $30. I totally understand. I have the cheapskate gene as well. Either diode is OK and will work, but check out the link for
Perihelion Design. Here is their
propaganda sheet of why its better. I know aeroelectric poopoo's the idea; probably because he didn't think of it first. Why waste energy? Periheliondesign has a good price; wholesale they cost $25-$29 anyway. They really are better than any diode you can get for what we are using it for.