The Eneloop spec. sheet I have in my files at home (not at my current location to post here) clearly states that they should never be charged at high rates without temperature monitoring. Eneloops should have the charge terminated as soon as a very minimal temperature elevation is detected. I don't have the temperature rise spec. handy to quote here ... sorry but I do know that temp. rise tolerance is far less than for other NiMh cells. Charging Eneloops at 1/10 C is considered safe and they will tolerate a fair amount of overcharge w/o cell damage. Yes, you certainly can charge these batteries at a 1/2C rates or even at greater levels such as 1C, but their lifespan will almost certainly be reduced if you don't keep a very keen eye on their temp. rise. As most people don't monitor temperature rise for RC applications, its just easier to use reduced and safer charge rates.

There is no reference to cell temp. rise during charging on the spec. sheet you published. There is just one small reference that proper charging equipment should be used. I would assume that proper equipment would include temperature monitoring.

John's charger only charges at a 1A rate regardless of what the switch setting is. The switch setting only applies to how the charger treats the battery after the peak detection charge cycle is terminated.

I've grown to like these batteries quite a bit for transmitter and ignition applications. But .... I've also grown to respect their limitations.