I tried this affordable Lithium battery capacity tester and liked it so much that I got four more of them. These can also test other types of batteries up to 15 volts max.
I go this to try out on my Lithium batteries and it works very well. I later put a passive heat sink on the resistor to keep it cooler and added some alligator clips so I can test any type of Lithium battery.
I have been running capacity tests on all kinds of Lithium cells from 18650s to pouch cells with no problems. This seems to be quite accurate because the batteries are showing near their rated capacity every time.
I got four more and may eventually end up with ten of these so I can test more batteries at a time.
You can get yours here:
https://amzn.to/30XZdcE
The Do It Yourself World LLC
http://www.thedoityourselfworld.com
Get off the grid for $5,000 or less
http://www.theoffgridproject.com
DIY Tube Video Community
Your alternate video sharing community
http://www.diytube.video
Get help with your projects or share your experiences
http://www.thedoityourselfworld.com/forum/