Need 18650/21700 batteries for Sofirn SP36 BLF - SC31 Pro - C8G - C8F - HD20

Batteries and Chargers Rechargeable Batteries
1

Hello fellow flashaholics!


I recently got some awesome Sofirn (/Wurkkos) flashlights, most of them without batteries because I don’t need the small included charger and figured I could buy some better batteries down the line:

  • Sofirn SP36 BLF 5000k (4x LH351D) [3x button-top 18650]
  • Sofirn SC31 Pro 5000k (1x SST40) [1x 18650]
  • Sofirn C8G ~6500k (1x XHP35 HI (I think, I should have a closer look at the LED dye…)) [1x (unprotected?) 21700]
  • Sofirn C8F 5000k (3x LH351D) [1x (unprotected?) 21700]
  • Wurkkos HD20 5000k (1x LH351D, 1x XP-L HD) [1x unprotected 21700]

I love every single light, each one for a specific use case (EDC/walking/searchlight/worklight/…). I’m using the included Wurkkos 21700 battery now in the HD20/C8G/C8F in a rotation, or otherwise a Sofirn 18650 unprotected button-top battery with a converter. In the SC31 Pro I’m running the included Sofirn 18650 unprotected button-top battery and in the SP36 some Liitokala protected 18650 “NCR18650B” batteries I got a few years ago.


The lights perform very well, but I’m pretty sure I could buy some better batteries for them. I live in Belgium so buying from nkon.nl is logical. There I was looking to buy 4 Keeppower 18650 3500mAh (protected) 10A (Button-top) batteries for my SP36 and SC31 Pro. It seemed to be the best price/capacity ratio for button-top batteries, but perhaps they aren’t the best for high-drain applications? I’m looking for the best capacity/max amperage combination…

For 21700 batteries I don’t really have a good idea what I should get. Since protected batteries don’t fit my charger and the HD20 I won’t buy one of those batteries, but there are a lot of options remaining… Should I get some Keeppower INR21700 5000mAh 10A batteries (out of stock though :confused: ) or Samsung INR21700-50E 4900mAh 9.8A (considerable cheaper and in stock) ? I really don’t know, all comments are welcome! Thanks!

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I’ll probably use the Liitokala protected 18650 “NCR18650B” batteries down the line in a Sofirn LT1 BLF because that one shouldn’t have such a high drain… I don’t have it yet since I’m holding off until they release a new version (hopefully with powerbank functionality and red light :innocent: ).

3

The Keeppowes will trip at 8.3A, using them in the SC31 Pro at turbo looks like a bad idea. Use either a NCR18650GA for max capacity or something like a Samsung 30Q for more lumens.

The C8G may still work with the INR21700-50E, but it comes with a 4000mAh battery, it’s a sign that they believe it needs a higher drain battery, from the review it’s unclear if the step down is only themal or also from voltage. The C8F certainly will benefit from a higher drain battery. If you can wait for overseas shipping, buy from Vapcell a 5000mAh 50G (Gold) or a 5000mAh 50T (Red). Otherwise buy a Samsung 4000mAh 40T from Nkon or wait until the Molicel INR21700-M50A is in stock.

4

This is a good web site for reading battery reviews. I have bought many batteries from them and they are all 100% legit.

I typically use the:
Samsung 30Q and Sony VTC6 for 18650
Sony VTC6 and Molicel P42A for 21700

This is just what I use but there are too many good options out there.

I only use button top for protected batteries as this is the way they typically come.

Button top adds unnecessary cost and significantly reduces the selection options.

No reason to use button top unless you absolutely need to.

The standard battery for all of these performance lights are unprotected flat top.

5

Dunno 21s but I hear “40T” thrown around a lot.

For low-stress lights, go for a panny-B or sanny-A (’GA, actually). Great capacity vs (ie, at the expense of) drain.

For more high-strung lights, you can’t really go wrong with 30Qs, as they’re my go-to cells for most everything.

Included Sofirn cells are actually quite decent if you opt for the kits. Most differences in Real Life™ you’ll only really notice with a meter vs observation.

6

1) Sofirn C8G uses XHP35-Hi (unspecified color temperature, but probably around 5700-6000k initially, but later became more ‘neutral-white’ 5000-5500k color temperature).

In Sofirn’s website, they recently listed that due to difficulty in getting XHP35-Hi LEDs (side comment: maybe difficulty in getting XHP35-Hi at a reasonably cheap price?), they have changed the C8G to SST40 (5000k).

In my simple tailcap measurement, the C8G (XHP35-Hi) uses around 6 Amps, but the C8G (SST40) seems to use only around 5 Amps on Turbo. This means using a higher-capacity 21700 (10Amp rating) would be good enough. Suggest the Vapcell G50 (Samsung 50G, which is supposed to be an improvement over the Samsung 50E).

2) SC31 Pro uses 1x SST40, based on my tailcap current measurement, doesn’t exceed 8 Amps, so some protected batteries may trip, or when the protected battery has low capacity left, it may trip earlier. Suggest an unprotected 18650. Use something like Samsung 35E, Sanyo NCR18650GA or LG MJ1 if want higher capacity.

3) C8F-21700 probably benefits from higher-drain batteries, I tested tailcap current to be around 10 Amps (or possibly a bit more), but probably no need for “Samsung 30T”. I think Vapcell G50 (Samsung 50G) unprotected would be a good choice. Or maybe the Samsung 40T / Molicell P42A would also be good (higher-drain, less voltage sag) but with a bit less capacity than the 5000mAh 21700.

4) SP36, as long as 3 batteries are used, I think some protected button-tops may be able to handle them. (I’ve tested some protected Panasonic NCR18650B that trip at 6 Amps, but using 3 of these on the SP36, they work OK, I have not tested when the protected battery is “low-batt” though. I’ve tested another batch (different supplier) of protected NCR18650B that trip at just 3 Amps — using 3 of these batteries will trip on the SP36 when set to Turbo). I’m unable to do tailcap current test for the SP36 though…

5) HD20 - unfortunately, haven’t tested the tailcap current of this model… I suppose using single or 2 LEDs, they do not consume too much power, so a high-capacity 21700 (eg. Vapcell G50 / Samsung 50G) will work well.