I use
this load tester and
this adapter to access the contacts easily / safely. It's a great little gadget; it can do constant current, power, resistance, or voltage - I'm almost always using it in constant current mode with a voltage cutoff. I typically test batteries at 1C, though it can also do up to 20A which is useful to test for voltage sag.
This listing has adapters for more brands.
It really highlighted for me the need to break in Nimhs, I saw 50, 75, and then 100% capacity out of the first, second, and third full drain/charge cycles on new packs and even individual cells.
I've seen your work testing lipos and AA's, I'm impressed. I'd like to make that kind of information available about more batteries, it really is criminal how unenforced capacity labeling is, at best you raise a stink with customer support and get a refund.
The (knockoff) Makita batteries I've tested are the included 3AH, tested ~2500mah, which I'll count as a pass.
I bought a $20 "6ah" cheapo, only 2000mah, and a $45 "5ah" that actually delivered 4ah before cutting off at 16V, though its built-in meter still indicated 33% capacity left. I'm not keen on taking these down to 0% because they've got less-than-ideal balance charging solutions, the plug isn't a balance plug like hobby packs have but more of a smart interface for the charger...
The included battery doesn't even use a Makita charger, but a DC adapter that plugs straight into it. Let's see how long the balance lasts...
I've tested my 1600mah Nimh 2/3A Receiver packs and generally gotten 1300mah out of them.
Turnigy's 4200mah cells and Zeee's 4200mah nimh Sub-c's delivered their labelled capacity.
In defense of the cheap packs, they still ran the heat gun fine and even for 10 minutes each, which is enough for me to get use out of, and for below $30 I can't complain about that.