I have two fully auto Hudy. My pyramid and MMR 24 will not work on them. all my stuff were bought new.
I used the small 12v gel cell starter battery to true my tires or the car battery if I am cutting a lot of tires. The big car battery is the best, nothing beats 500+ cold cranking amps. I use a $10 jumper cable to lenthgthen the wires so I can set the tire truer on the floor. That way I don't get any tire shaving in my engine compartment.
I thought about getting the 30 amp bull dog or a $180 gell cell car battery. The $10 jumper cable works the best and cheapest. The most I cut at one time is 6 sets of 1/8. 24 tires. I have two small 7 ah 12v starter box batteries. I can cut 3-4 sets of 1/10 foam tire with one of them.