Bests & Worsts Reviews from Amazon

I own five vehicles, some new and some a little older. In the past I have had the batteries tested by professional mechanics. They of course used top of the line equipment with the latest technology. I wondered if I could do the same type of testing at home. I did my research on the internet. I looked at numerous videos on youtube and read what people had to say about various battery testers on the Amazon site. I was impressed with one video showing a mechanic using the Topdon ArtiBattery 101. I looked at the ratings for this product on Amazon and found it to be highly rated. It had a 4.8 rating with 91% being five stars. There were no 1 and 2 stars. I was impressed. Because of the high ratings I ordered one for myself and one for my son. My son's was to be a Christmas gift. I recently purchased a 2007 Z06 Corvette with a one year old battery. Since the car was new to me I wanted to find out the condition of the battery. Within the last year I purchased the Schumacher 100 amp Load Tester and Voltmeter Battery Tester and the Dewalt 30 A Bench Battery Charger. My battery is a Super Start Extreme BCI 90 with 600 cca. I used the Dewalt and it told me that the battery needed to be charged. I charged the battery and even took 24 hours to recondition the battery. I then tested the battery four different times with my Topdon. All were done within minutes of each other. Each time the State of Health went from 33% to 39% to 30% to 40%. The state of charge stayed even at 98% for all four tests. I then tested with the Schumacher and it said that the battery was good. Since the State of Health was so low using the Topdon I opened up my son's Topdon and did a comparison test. Here are the results: My Topdon said the State of Health was 34% and my son's said 80%. My State of charge said 33% and my son's 25%. My cca showed 330 A and my son's 460 A. My Topdon said to REPLACE the battery and my son's said GOOD-RECHARGE. By using the same product I am getting two different readings. Which one is correct? Based on one I would be looking at recharging the battery even though it had been recharged the day before the test. Based on the other I would be buying a new battery. I will now take the car to my mechanic and have him test the battery. Once this is done I will do an update to this information. In the meantime I will be sending the Topdons back to Amazon. I just do not have faith in their reliability. Sorry for the one star Topdon but I cannot trust your product.