I have a 400 amp 10 pound charger unfortunately it drops to 30 if the clamps are not shorted together merely connected to a 12 volt battery. I give up. Let's see I am so many years old. That means that six pound rainbow I caught at age ten weighs 78 "new pounds"
The old group 4 6-volt truck battery or 7-D had heavy plates but not very many of them. Replaced with "new style" group 31's in the eighties. A pair of 31's put out 1,600 CCA versus a pair of group 4's 550 amperes @ 12 volts.
Carry a bathroom scale. If people advertise a 66 pound battery and you get to the parking lot and find it at 62.5 the store MUST take it back if a refund is demanded. It's flat out indefensible consumer fraud.
I would limit this trial to be used only with a digital scale. The better half knows how to make a mechanical scale, cheat.