The last time I posted to the blog, I was just getting started with measuring the capacities of my AA NiMH rechargeable batteries. With twenty-four 2000 mAh Eneloops and sixteen 2500 man Amazon Basic batteries, the process was almost painfully slow.

The Lacrosse Tech BC–700 charger I got can discharge at no better than 350mA, and charge at no better than 700mA. That means for a 2000 mAh battery, that’s almost 6 hours for each discharge and 3 hours to fully charge. On top of that, before the charger discharges the battery it fully tops it up, so there’s a further charge cycle—though a much shorter one than a full charge—that has to complete as well. At 9–12 hours per 4 batteries, I averaged about somewhere just under 2 sets a day for the duration.

The good news is that time has been pretty kind to my first generation eneloops. I looked at both the percent of the typical and minimum capacities, anything lower than the minimum I’ve pulled from photographic usage but I’ll probably keep them for remote controls and computer mice since they’re low power applications.

Eight of my 24 Eneloops I’ve deemed unworthy to continue as part of my photographic energy reserve. All of these batteries tested at less than the published 2000 mAh minimum capacity for the Eneloops. The worst of these measure at a dismal 1583 mAh, the best at 1863 mAh, with most in the 1700 mAh range. I’ll probably keep these for the time being and stick them in IR remotes or something low power.

I expect that all these failures were from the very first 8 Eneloops I got back in around 2009 or 2010, but I can’t be sure.

On the other hand, the vast majority of my batteries, 15 of them, all tested to having more than the 2000 mAh typical capacities. Looking though my records, I think most of these batteries were bought in 2010 and 2011.

All told, I’m very happy to know that given my 4–5 years of abusing these batteries, they’re still trucking. The first generation Eneloops certainly have proven to be reliable in the long term. Of course, they’re also obsolete and no longer produced in favor of newer chemistries.

I also ran my Amazon Basic High Capacity batteries through the test. These are all basically brand new batteries, and including the charges applied during the testing, they have all of 3 charge cycles so far. I mention this, because as my research has lead me to believe, NiMH battery capacities will improve over the first few charges. Though I have no idea why this would be the case.

In any event, of my 16 Amazon batteries, only one tested below the expected typical capacity of 2500 mAh: it measured 2470mAh. The rest all tested in excess of 2500mAh, with 5 testing above 2600mAh, and one peaking at 2690mAh. If these hold up as well as my old Eneloops do, these will be really nice batteries for the next 5 years.

After I have about 20 charge cycles on the Amazon batteries I’ll be remeasuring them again to see if their capacities have improved, so there will be yet another post about them sometime, if I had to guess, in the next year or so.

All told, I really wish I had known enough to label and group my batteries back when I started. My initial 8 batteries ended up getting distributed throughout most of my battery sets, and ultimately that causes each sets overall performance to degrade. Moreover, since the sets ages weren’t all known, I couldn’t just retire or toss an underperforming set without having a very high risk of tossing perfectly good batteries in the process.