Battery tester accuracy?

[nthach]

My dad had the aux battery in a 2017 Prius die a few times, he keeps a jump pack with him. AAA came out to give him a jump but their Midtronics tester said the battery is weak/in need of replacement. I’ve tested it with a Topdon BT101 and it said good battery. Is there something special the Midtronics has that the Chinesium tools don’t?

The car is a cab, so there is aftermarket “unfitting” done, wiring for a cheap Android tablet, POS receipt printer/PIN pad and a dashcam so there’s some parasitic load that doesn’t go to “normal” sleep. I’ll have to put a DMM on it to do a check. He wanted me to put in a new battery - Costco didn’t have a H4/40 battery in stock. I decided to install a Deka flooded battery from the local parts house. Made in Austria, Walmart was $20 more expensive.

 

[charbaby]

IDK so this is of no help or answer to your question.

I typically do my parts shopping shop at AAP. So now & again I’ll stop in to have my older car batteries tested for free. Usually the batteries show to be in good shape.

Then I will drive directly across the street to AZ and have them do the same. At AZ, the same battery, same day, the battery almost always show to need a replacement.

Often, I’ll go to AZ first then to AAP and the results are the same…Just saying!