This week I received my order of Lithium Manganese (aka LiMn, IMR, or LMR) batteries from bestinone.com. They had great prices (now a little higher) and carry a lot of different sizes of batteries. The advantage of LiMn batteries is they are supposed to be able to safely provide high currents of 5C to 8C based on their capacity. Their capacities are lower than standard li-ion batteries (Lithium Cobalt). So, for instance, whereas Trustfire flame LiCo 14500 batteries are 900 mAh, the LiMN batteries I got are 600mAh. AW sells IMR batteries in that size that are also 600mAh, but for $6.50 each whereas I got a pair for $5.99 (now they are $7.99, and bestinone has a $2.27 handling fee per order, providing a tracking number).
I don't have a scale, but these seem pretty lightweight. The 14500 and 18650 sizes do not have button tops and will not work in a couple of my lights that don't have springs on each end (like my Ultrafire X1). Because these fall pretty closely in line with their nominal sizes instead of being an extra couple of mm for the protection circuit (LiMn batteries don't need protection circuits), the 18650 isn't long enough to make contact with the little spring on the 2.8A driver in either my L2P or 504B hosts. The voltage of most of the batteries out of the package was just over 3.8V except one of the 14500's which was 1.6V. LiMn batteries are not supposed to be left at a low voltage, but it charged okay.
I'll include some pictures later, but here are some dimensions:
10440: 350mAh, 44.35mm long x 10.15mm diameter (has a button postive end)
14500: 600mAh, 48.60mm long x 14.05mm diameter (flush positive end)
18650: 1500mAh, 65.30mm long x 18.20mm diameter (flush positive end)
The challenge is in evaluating the high discharge rate of these batteries. My Turnigy hobby charger has a maximum discharge rate of 1A which wouldn't even adequately test the puny 350mAh 10440, since that is just a discharge rate of 3C.
So I devised a test using my XM-L driven by the 8x7135 NANJG driver from KD. This drop-in draws a steady 2800mA which is pretty good exercise for the 600mAh 14500 (that comes out to 4.67C). The battery started out with an at-rest voltage of 4.18V. Testing was tricky because I don't have a 1xAA P60 host and I wasn't crazy about doing an endurance test with a XM-L at this current. I used my Solarforce L2i as a host with the head down in a shallow metal pan of water (just a few mm deep to get good contact) with the pan on top of some ice water to keep it cool. I left the tailcap off and connected clips to the positive spring of the driver and the rear threads of the host, leading back to my DMM and the battery. You've got to love magnets for some of this stuff. Every three minutes I would check the current which I was monitoring continuously and eventually I started checking the voltage under load (I went back and picked up the starting voltage under load with a freshly charged battery), stopping when I got to 3V (3.04V actually, close enough). Due to the declining voltage, the light didn't stay in regulation for very long at all, just 3 minutes. But no explosions and the battery didn't seem to get hot (and the ice water kept the light cool). Despite not being in regulation and the current dropping with the voltage, the calculated capacity actually exceeds the nominal: 667mAh measured instead of 600mAh nominal. I calculated the mAh by taking the average of the current at 0 and 3 minutes, multiplying by 3 minutes, and dividing by 60 minutes do get mAh. I did this for each 3-minute interval and then added all of the mAh values to get the total capacity.
| Minutes | Voltage | Current (mA) | mAh |
| 0 | 3.84 | 2850 | |
| 3 | NA | 2830 | 142.00 |
| 6 | 3.38 | 2540 | 134.25 |
| 9 | 3.38 | 2330 | 121.75 |
| 12 | 3.31 | 2020 | 108.75 |
| 15 | 3.22 | 1670 | 92.25 |
| 18 | 3.04 | 1030 | 67.50 |
| Total: | 666.50 |
I may try something similar with the 10440 and 18650. I connected the 10440 to the same drop-in and measured 2500mA draw, so 7C seems to be its maximum output. AW doesn't even offer 10440 IMR's, so I kind of wonder about this size being true IMR. But 2.5A is pretty good. I might test it with a 1400mA driver, which would be a 4C draw.
I will add to this review, but for the 14500 at least, these generic LiMN batteries seem to be pretty decent and fairly well suited for driving an XM-L, albeit briefly, even though I don't have any AA-size lights with an XM-L (yet!).
I mailed these batteries to Mitro in June and he did some much better tests on them than I could do, testing them out at different current levels and creating graphs. Those results confirm what I found, which is the 14500's have higher than expected capacity, the 10440's have less, and the 18650's have somewhat less. But he was also able to test that the 14500's and 18650's hold up pretty well under higher loads like you would expect from true LMR batteries. So the conclusion I make is that you could do okay ordering the 14500 and 18650 batteries from bestinone.
Mitro's tests start here: https://budgetlightforum.com/t/-/2325#comment-49954
