This LiIon battery is about D cell size (It is slightly longer), this makes it four times a 18650 in volume.
The battery has the rated capacity and the two batteries do track fairly well. The protection does not allow 7A continuous current draw.
Conclusion
Like 26650 batteries the voltage is higher on this battery and it has a bit more capacity than the best 26650, but at twice the volume.
The actual performance is acceptable, but using 3x18650 in parallel would give more capacity using about the same space.
Notes and links
Not many LiIon chargers supports this battery size, some possibilities are Xtar VP4 and Enova All-80.
It fits in an Xtar SP1, but I put a copper coin at the cathode because the charger's contact doesn't reach past the wrapper. Needs a more pronounced button.
For a D cell Mag, I would actually prefer the Feilong 32600. It has somewhat less capacity due to being a smaller cell. But it’s actually the right length for the light.
I have no idea what cells are in these but have used the protected version. I Have tested the protected version and they come out at about 6200 Ah at 3 amp discharge. The small positive contact needs a small magnet on it to charge in my TR-008 charger. I also tested the unprotected Trustfire at 3 amp discharge and come up with 6500 Ah when new. Testing six months later with little use on the batteries showed 6200 Ah. I have a feeling that the longevity of these cells will not have the life span of a good brand name cell.
All testing on an ICharger 208B. End of testing voltage was set at 2.8 volts.
Since these are such a thick dense cell, I charge them at 2 amps to allow for a more even and thorough top-off at termination. @3 amps, I noticed the cells begin to warm up and then drop more in resting voltage after charging. If you have the time, 1A might be even better.
Okay, thanks. I got impatient and just went for 2A since the TrustFire® charger is 1.3A and I didn't want to overheat the steel spring. You are right, the cell didn't even get warm (the spring did, though.) It's still in CV mode, so we'll see what happens when the charge cycle is complete and the cell has some time to rest.