Battery Hold down Straps and Lock
I used 3/8 X 1 inch aluminum strip. First I pop-riveted a hinge on the end of the strip then pop-riveted it to the battery frame on the tongue of the pop-up.
As you can see I went to the top of the battery box and bent a 90 back across top of box. I extended the length about 3 inches past the other side of the battery box.
I pop-riveted the other strap to the frame and ran it up to the other strap and bent it back 90 degrees under the other strap. I then drilled a hole through both straps large enough for a large bolt to go through. Before placing bolt through hole I drilled a hole through the bolt that a small padlock would fit through. I placed the bolt in the hole, tightened the nut and put the pad lock through the hole in the bolt.