Perhaps this photo will help.
It can deliver regulated 14.75 V at almost 30 A.
It is a very good automobile alternator simulator.
It can also be used a a battery charger.
Note the homemade #10 wire shunt.
The multimeters were $2.99 at HF.
They will be direct wired to the last 2 ATX's for 10 V as a substitute for their 9V batteries.
The project cost me less than $20.
BoyntonStu