With the rear running lights up and mmmm running on our Tour Easy recumbents, I could finally retire the Planet Bike Superflash blinkie after a decade of constant use:
For the last six years, a set of eight Panasonic Eneloop AAA cells have been marching in pairs through the Superflashes in lockstep alphabetic order. We ride several times a week, less in the winter, and I changed the batteries once a week whether they need it or not, so they’ve gone through maybe 200 charge cycles. With four pairs and two bikes, that’s 100 cycles each.
They’re not dead yet, but they’re showing signs of age:
In round numbers, the capacity is down 20% from their original 850 mW·hr. The 50 to 75 mV depression is probably more significant for an LED power supply intended for alkaline cells, as the light was running from 2.3 V instead of 3 V.
They worked surprisingly well, all things considered.
Nowadays, one might use bucked lithium cells with a constant 1.5 V output for their entire discharge curve, although I absolutely do not believe a claimed 1000+ mW·hr capacity.
The Smell of Molten Projects in the Morning 
1Whr (1000 mWhr) seems reasonable and witnessed(1) for AAA/10430/10440 size. BUT: this is before a step-down voltage converter. If the converter has 80% efficiency than these are equivalent to the NiMH Eneloops (1000*0.8=800 mWhr). If it has 95% efficiency: they will have 950 mWhr(15% more capacity than the Eneloops).
A LiFePO4 cell with its 3 volt flat discharge curve is also a possible variant. But the AAA/10430/10440 size is a very rare find. They have smaller capacity (in mWhr) but live a lot longer and lose capacity very slowly.
References:
(1) https://lygte-info.dk/review/batteries2012/Vapcell%20INR10440%20320mAh%20(Green)%20UK.html
(2) Here are some results: https://lygte-info.dk/info/batteryIndex.html His reviews could be found at https://www.candlepowerforums.com/ and https://budgetlightforum.com
You have much better battery test equipment than I do! :grin:
At least for our bikes, they’re down to one big traction battery and a little 5 V USB pack for the camera, so I intend to punt until the little packs fail.
Another important point: currently NiMH Eneloops are not made in Japan: https://archive.li/w5OZL#selection-4453.0-4465.30
FDK Industrial and Fujitsu NiMH are made in the factory that once made the Eneloops.
(1) https://www.fdk.com/battery/nimh_e/
(2) https://www.fdk.com/denchi-e/rechargeable_battery/
The various
archive.*sites recently disappeared behind an impenetrable Recaptcha wall; it must have something to do with all the Internet armor I run.Wikipedia observes “There are many counterfeit Eneloop batteries”. :sigh:
It’s interesting to see a real world report on degradation with time and use.
Do you notice an obviously shorter use per charge in the winter? Nickel batteries seem to be one of the more temperature affected chemistries.
We pretty much don’t ride below 40 °F and the batteries lasted a week even under those conditions, so they worked for our simple needs.
I am so glad to have gotten Yet Another Set of Batteries off the bikes!