Smart Isolator

Our motorhome uses a conventional isolator between the coach and starter batteries. Basically just a heavy duty solenoid relay. It worked. Until it burned out. Here's why.

After replacing the solenoid a custom circuit was developed to reduce power and prevent future burnouts. It's not the only solution just my way.

Correction. If you found the video confusng about the clunk/click and long/short delay, then blame me and replay it with this in mind.

1. Long quiet as Timer1 counts down. (power ~0.15W)
2. Loud clunk when solenoid energized at full power. (resistor shunted)
3. Short quiet while Timer2 counts down. (power ~18W)
4. Faint click when resistor unshunted. (micro relay contacts open, power ~3.5W)

So that works a lot better. It was also a fun project that blended electronics and 3D printing a custom solution. I see two more of these smart isolator builds in my future for trucks with auxilary batteries. Once a working prototype is developed, production in any quantity is just rinse and repeat. Or tweak subsequent versions if requirements vary in some way.