I’d been seeing a lot of different brands of rechargeable lithium ion standard-sized batteries on the market, and couldn’t decide which ones to buy. Hence, I bought many of them. Hopefully this helps you out of the same conundrum!
I built a test “rig” (really just some plywood) which consisted of 5 each of milliamp-hour meters, 4-position battery packs, and 12 Ohm resistors. In all, I tested 7 brands of lithium cells, as well as 6 sets of alkaline batteries (as a point of reference for capacity), 1 set of non-rechargeable Energizer Lithiums, and 1 set of NiMH Panasonic Eneloop cells.
The batteries were discharged until their aggregate voltage reached 3 (or 0.75V per cell) which I felt was a comparable “empty” voltage to alkaline cells. It should in theory be irrelevant, as all of the cell’s converters are supposed to deliver a constant 1.5V. So they would dip rapidly from 1.5V (well, it’s a bit lower under load — see the spreadsheet) to almost 0V. Theoretically.
I compiled all of the data (and then some) into a Google Docs Sheet: https://docs.google.com/spreadsheets/d/1ssAuFEysVVlKPtFfrIxoYvVqXOxYQG9o0NkWmeibzlQ/edit?usp=sharing
I didn’t cover this in the video, but I was quite surprised that the capacity of the Eneloops was in the vicinity of the capacities of the lithium cells, as were some of the Alkaline cells. The Energizer Lithium batteries showed an extraordinarily high capacity.
Lithium ion cells do have a higher energy density than the other chemistries, but I have a feeling that their relative downfall here is that the manufacturers also have to squeeze a step-down converter into the small AA package size. Then again, the Energizer Lithium cells must also have a DC-DC converter on board as well, and they clocked in at 3427mAh compared to the best of the rechargeables at 2068mAh. I’m not sure wherein the discrepancy lies, so if you have any idea please let me know in the video comments.
The tests were performed by fully charging all the cells, fully discharging them, then fully charging them once more before data was recorded.
For posterity, and because they weren’t really shown in the video, below are the discharge tests at 100x speed. Unfortunately because the mAh meter vacillates between showing Voltage, Amperage, and mAh the readings are a blur, and pausing it on just the right reading can be tricky. But in any case you can see the final readings at the end of the video, and when each of the batteries dropped to less than 0.75V per cell.
Finally, if you’re curious as to how I got the charge times, it was nothing fancy. I recorded the batteries as they charged, and reviewed the footage with an attached time code to find the end-of-charge: