JimboZA:
Yes Lefty that makes sense, but that RS one does say it measures AA, AAA, C and D on the same load of 35mA. PP3 9Vs it does at 20mA; and it says not to test Nicad batteries at all.But as a matter of principal, and to test my understanding, it is presumably batter to test a cell under at least "some load" whatever that might be? And presumably, the closer to the load characteristics encountered in real life, the better?
Certainly measuring a batteries terminal voltage without any load is the least desirable method, and a small fixed load is better then no load, but a load proportional to the the cells normal capacity would be even better I would think.
I know the R/C folks into using high performance (and expensive) battery packs for their aircraft often purchase battery 'cycle testers' that will measure the true mAH capacity of a specific pack by placing a user selectable load resistance on the pack and measuring the voltage drop over time to then come up with the true pack discharge capacity, which does slowly decrease over time and with total number of pack charge/discharge cycles it has accumulated. With some R/C aircraft having some thousands of dollars invested some take proactive battery pack testing very seriously.
Lefty