The feature most germane to this topic is “refresh”. This feature keeps running slow drain-then-charge cycles until the battery stops getting better. This does an amazing job of bringing back dead batteries. I had two sets of beat up old Sony rechargables that been through 3+ years of heavy use and were barely holding a charge anymore. Two days on the refresh cycle and they’re literally as good new — they each hold their rated 2000 mAh of energy.

Which reminds me of the other neat feature, it tells you how much juice it’s put into your batteries, so if just one battery of a set is going bad you can “recycle” just that one. Handy.

I still keep my batteries in groups, but they’re not labelled, just rubber-banded together for easier handling.

Last thought, to “inspirationbit”… check out Sanyo Eneloops. They’re advertised to hold a 70% charge after two years. They actually ship precharged, which no other NiMH batteries do. The only downside is they’re a bit pricey, and they top out at 2000 mAh. But worth it IMHO.

Here’s a quote from the Wikipedia page on NiMH batteries:

NiMH has had a somewhat higher self-discharge rate (equivalent to internal leakage) than NiCd in the past. However, this is no longer the case. The self-discharge is 5-10% on the first day[1], and stabilizes around 0.5-1% per day at room temperature.

So if your batteries are discharging faster than that, you might consider picking up some new ones.

Aside from this, I know if the set is charged by the arrangement of the batteries in my plastic cases. If all the batteries are facing the same way (positive end up or down), the set is fresh. If the batteries alternate (like when you pop them out of the flash), the set is spent.