That tester is a "P.T. Barnum special"- - - -it's made to sell batteries, not test them. To load a battery properly, a tester must have a carbon pile variable resistor, and an ammeter to monitor how much load is being applied. The one in the ad is a "ones size fits none" that applies a fixed current load without any regard to what a specific CCA rated battery needs for a proper test.

Here's a real battery load tester:

www.ebay.com/itm/293816270395?

Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!