Anyone interested in a couple of 80A isolators and willing to buy about $10 to $15 worth of parts and build either one?
The following circuits may be of interest. I designed these for my Car-PC. They are adjustable and easy to make. One is basically an 80A solid state switch. The other allows full charging of a secondary PC battery while “always” keeping it isolated from cranking voltages via a 35A diode, in other words it only connects directly when the alternator is charging and above 13v.
In my system I didn’t want to count on the M4-PSU low voltage programming to protect the main car battery, therefore one unit (80A switch) is wired as a low voltage cut-out to protect the main battery.
In an attemp to achieve glitch-free 100% reliable starting of the PC, PSU and various USB microprocessors controllers under all Vehicle starting conditions and aux battery state of charge conditions I built thse circuits and found this layout to work faultlessly, no moving parts and no heat when mounted on a small heatsink (Aluminum case.)
Part of my Car-PC wiring.
Clearer detail in this PDF.