[Tx Firefighter]

I built them out of Chevy starter solenoids. I guarantee you they are stronger than anything else out there. You take the spring and plunger out of an old starter and use a strap of steel across the top to hold it together. If it ever fails, a new GM starter solenoid is about 10 bucks. I build them heavy duty because I work on a lot of old cars with super heavy door latches that are usually half way worn out, so they need the extra thump from a strong solenoid.

Even if you have a locking hood and can't get to the battery, just jack the vehicle up and hook the jumper cables to the starter positive terminal. It's all the same.