I appreciate all your effort, I need to remember that the switching of various loads up to as high as 150 amps may prevent me using a Voltage sensitive device. My highest load (150 amps for 5 minutes) will drop battery voltage by an apparent 1V due to internal battery resistance. I say apparent because I believe that in the milli-second range on first connection it may be higher than 1V but too fast for my meter to read.
With this in mind I shall try the timer option first, by the way I now know that the controller if set to switch off at 12.1V does not switch back on until 12.6V so the hysteresis is good I think.
On another note (perhaps it needs a new topic?) and hopefully a simple question; If I wanted to regularly (say 5 times a day) dissipate say 300W for a few hundreths of a milli second (Guessing a 1/4 second) could I use a tiny 1500W TVS Zener? They seem so tiny for such a high load and cost just a few dollars!
With this in mind I shall try the timer option first, by the way I now know that the controller if set to switch off at 12.1V does not switch back on until 12.6V so the hysteresis is good I think.
On another note (perhaps it needs a new topic?) and hopefully a simple question; If I wanted to regularly (say 5 times a day) dissipate say 300W for a few hundreths of a milli second (Guessing a 1/4 second) could I use a tiny 1500W TVS Zener? They seem so tiny for such a high load and cost just a few dollars!