[Mr V]

The Wel-built load tester like most inexpensive load testers intended for testing automotive starting batteries just load the battery at 125 or 100 amps so you can measure the voltage and infer the CCA based on the voltage under that load.

They do not put excessive strain on the batteries if occasionally used per their instructions and they are a good way to see how the battery will perform when asked to supply the kids of loads that one might see in a match.

The Battery Beak is good for seeing the internal resistance of the battery, which does give you some insight as too its health, and it's SOC.

A volt meter will only give you and indication of the SOC but no info on the health of the battery.