"Carbon Pile" load testers are the only ones worth buying. They have a big stack of carbon resistor plates several inches square, and an ACME thread screw to compress them together. The good ones will have a carbon pile capable of applying up to around 1000 amps of load to a battery, which is more than the CCA rating of anything but a heavy duty Diesel truck battery. Anything else is just wishful thinking where battery load testing is concerned. A good load tester will cost around $200.00 or a bit more- - - -it's worth it!
The price jump between 500 amp and 1K amp is pretty noticeable.
www.ebay.com/itm/164885207331?Jerry
