These batteries are not 18650, but 16650, this means that they are about 2 mm less in diameter. This smaller diameter makes them a good fit in light designed for 2xCR123 batteries (There might still be problems with the voltage being too low and that length is slightly longer than 2xCR123).
Sanyo 16650 Unprotected
Capacity: min. 2100mAh
Full charge: 4.3V
Nominal voltage: 3.7V
Cut off: 3V
The batteries are 4.3 volt batteries, but can be use on 4.2 volt chargers with a capacity loss.
The batteries arrived in an envelope without any other protection (intl-outdoor has informed me that they have changed to a better packing).
When charged to 4.2 volt the battery does not reach full capacity, as can be seen on these discharge curves. The 5 ampere trace is cut short due to the protection in the battery.
The protection trips at 5.6 ampere, but as can be seen from the discharge test, the battery can not sustain a 5 ampere discharge, but will shut down after some minutes.
Charging at 4.3 volt
Using 4.3 volt as charge voltage did not increase the capacity of the battery, a look at the charge curve explains why.
The battery has a over voltage protection circuit and this circuit is for 4.2 volt cells, i.e. the charge is stoppend when the battery reach 4.3 volt and the CV phase is missing. Using a charge voltage of 4.28 would probably have reached close to the full capacity of the cell.
The battery size is interesting and can be useful (It worked perfectly in my RGB Quark) and because it is a new generation LiIon it has better capacity than 17670 batteries, even when only charged to 4.2 volt. I do not see the early over voltage protection as a big problem, because I believe most people will charge it on either a 4.2 volt charger or a hobby charger that can be adjusted to just below the trip point.
All in all I will rate it as a good battery.
Notes and links
The batteries was supplied by intl-outdoor for review.
Having seen Sanyos own documentation showing huge sag with a 2C discharge, I had wondered just how well these would cope at 3A, and while there is obviously voltage sag occurring, it isn't excessive, and capacity remains appreciably higher than the de facto standard AW 17670 cell. A good deal lower than the stated capacity, but still the highest (measured) capacity for a cell in this size range.
I ordered three of these with a number of other cells a while back - took a while to get through UK customs - but on receiving the package, only one of these cells was included. The other two are being sent separately. Once I have a couple, hopefully I can repeat some of your testing for comparison.
Doh! Yes, you did state that your initial test (what I was looking at) was not to the full CV rating of the cell. Had forgotten that. Having read further, I now also notice that the over-voltage function of the protection circuit is cutting in at a little too low of a value.
Wanted some unprotected 18650 for one of the Ebay USB device chargers. Being the budget type I resorted to “Dumpster Diving” some of the local recycle bins. My overall usefull yield from about a dozen laptop packs was 24 good batteries. Six of these were mystery orange unmarked batteries of a smaller 16mm diameter. They came from an Acer pack. Doing a google search turned up your posts here and on CPF. Am getting about 2000ma from these used cells charged to 4.2V. The mystery is solved. Fit perfectly in an old Streamlight Scorpion. Thanks for the great review.
No, that is not one of the batteries I have tested or have in queue, but I have tested the EagleTac 17650 1600mAh.
A easy way to see what I have tested of batteries in sizes around 18650 is the summary thread, the charts will "automatic" be updated when I publish a new review (You might have to press F5 in the browser to see it).