Originally Posted by Over59
Diodes is one of those things I never want to meet in a dark alley. They are oneway do dahs? "The Bat Cave Express" design is optimized for being "on the road". That's why the 12volt fridge. I didn't want gas on while making an 8 to 10 hour run. The schematic would be helpful.
I'm thinking I want to come off the alternator so I don't run the risk of draining the truck batteries while stopped over night without disconnecting. That's probably one of those diode issues again?
Diodes are nothing more than electrical check valves. Current flows one way only. Properly dimensioned, they are rarely a cause of trouble.
The Alternator is typically parallel to the battery, meaning that if you hook up to the alternator, it will still draw down your battery if you forget to disconnect with the fridge on 12V
. Maybe some sort of battery isolator coul dbe amployed?
Another way to disconnect the 12V as soon as the engin is turned off, is to use a fuel pump safety relay. Those relays read engine dwell ( or ignition rpm) and turn off as soon as the motor stops. But then you might as well wire a relay in the ignition circuit, which turns off when you turn the key off.
I can't see how you can provide an automated 12V management for your fridge without some sort of electronic device. You will have to somehow modify your tow vehicle's wiring to accomodate this.
I agree with your concern that each and every system that is added to the trailer/tow vehicle at some point can fail and cause you grief.