Best way to charge batteries

[Ether]

Originally Posted by DonRotolo

Generally, AutoZone uses a conductance tester such as a Midtronics, and not like a carbon pile of the olden days. In other words, a LOT like the battery beak. These are very fast, lightweight, and accurate, and do not rely upon the user's skill.

They may be accurate for what they do. But they do not measure the battery's capacity.

I have an old battery in my shed that passes with flying colors when tested with my "125 amps for 10 seconds" tester. But it fails miserably when subjected to a capacity test. So even if the high-load-short-duration test doesn't harm the battery, it doesn't really tell you what the true health of the battery is.

even a 150A load for 10 seconds will NOT damage an FRC battery. It's not good for this to be done on a regular basis, but 2 or 3 times a year is not harmful.

Yuasa NP18-2 datasheet: Maximum discharge: 112 amps.

MK ES17-12 datasheet: Maximum discharge current for 30 seconds: 360 amps.

Go figure.