Top critical review
Not very accurate (update on a replacement)
Reviewed in the United States on November 6, 2018
The two tests I ran were on a 12-v lead acid car battery. One test was performed without load switched in and another test was performed under load. A digital volt meter was also deployed in both tests. Without a load switched in, the digital volt meter shows the battery at 12.5 v and the BT-100 tester shows 12.2 v.
When under load, the digital volt meter shows 11.4 v and the BT-100 tester shows 10.8 v. The 0.6 v difference is significant since a good battery can be identified as weak or very close to dead, resulting in a premature replacement of a usable battery.
Update: I returned the unit. A few days later, I saw a 70% off sale. I decided to give it another trial. This time the BT-100 is almost right on top of what my digital meter gets. I guess the BT-100 quality control might be a problem. This is quite typical for something good but made in China.