12V battery at 12.5 volts. Should I worry about sulfation?

I’d read up about their accuracy first. For measurements in the range of say 10-100 milliamperes I’d stick with a simple digital multimeter: it may be more difficult to connect, but the readings are more accurate I think. It’s not that hard either, you just need to think it through.

note in the attachment: manufacturer specs accurac of 0.1 amp at low extreme. There’s a 1000 milliamperes in an amp, so that’s 100 milliamperes. And that’s its limit of accuracy. Somewhat analogous to using a 1/2” torque wrench to install spark plugs.