20700 Batteries What is real?

Wow! “Minimum 26650 battery size required.” That’s crazy! Looking forward to hearing how this turns out!

There is a short test, at 30A, of the 3Ah Samsung INR21700-30T versus the Sony 18650 VTC5A here:

(scroll to the bottom of the linked page)

The Samsung heated up to 68 degC and the Sony to 99 degC

Spent a few hours finalizing the big triple this afternoon. The new bezel worked out really nice and the way it’s done gives me some flexibility on the thickness of lens/o-ring. I salvaged the original tail cap by machining threads into the knurled 20700 tube and using this end as a “plug” in the 26650 tube. I had a copper exposed end with a large chunk of copper as the retaining ring inside it so I managed to save all that and it looks ok. Perhaps a bit makeshift but still, it works. lol At this point the big tube is just knurled, no grooves, may leave it like this as it feels pretty good in-hand.

That’s quite something!

Nice clean work Dale!!! TL

My review of the 30T is also up: Test/review of Samsung INR21700-30T 3000mAh (Gray)
And it can be compare to just about any other cell in my comparators.

From the review:

Now THAT is the cell we’ve been waiting for! :smiley:

At 10A you could just as well use a 26650 cell, but when current goes above 20A they cannot match the voltage and at 30A+ there is no competition.

While I DO want at least a pair of the 21700 for that high amperage ability, they’re much less capacity in the end so overall the differences aren’t what they may appear. Short term, yes. And I’ll exploit that when I can find a pair.

I agree.

For our direct drive applications there seems to be a diminishing performance return as the cell IR goes lower. This is because other resistance in the circuit becomes the limiting factor. So even though this cell about halves the IR of a cell like the 30Q, the performance might increase by 25% or less, and the energy density decreases significantly. I guess it’s just a matter of where one’s properties lie.

So it’s a really entertaining thing to hit 21A and 11,600 lumens in a flashlight, but with 4000mAh on tap the entertainment is short lived. If the 21700 could do 30A, sure it’d be awesome, but only for a few minutes. After the first few minutes it’d be the same as most any other cell, so…

Of course, I’ll do it. :smiley:

Edit: This debate reminds me of the Tortoise and Hare story, fast and furious for a few minutes but the long deliberate search wins so many times. For home defense, sure, 20,000 lumens in the face of an intruder can have a staggering impact and there’s no need for 30 minutes of it. Searching for a lost child during a storm in the wee morning hours would have a different demand on the light used. Or just one step down from Turbo perhaps. lol

Im designing a 2x18650 battery box for a caving light and I’m considering making it spacious enough to accommodate unprotected 20700. After all it’s equal in length and only a bit thicker than protected 18650. Just ordered two from nkon.nl (15,28€ shipped). They are rated 4250mAh.

Taking the very best 18650 compared to the 20700B and you just got 25% more runtime. I’m surprised 20700 haven’t taken off yet.

Well, price and size, and if they are just an interim stepping stone to 21700's. $8 here: liionwholesale.com/products/panasonic-sanyo-ncr20700b

I got one, and a couple 20700A's. Hhmm, I sure dunno what to do with them... Using one in a 26650 light that, if your'e lucky, takes a 70 mm cell, but sure doesn't make much sense when you have higher performance options like a LiitoKala 5000.

So... What usage scenario makes any sense for these things? They are a consumer item with no place to go...

At this point they only make sense if you can take advantage of their smaller diameter by boring out a 18650 tube or custom making a tube for it.

Yep, they are boring - just sit'n there....

I’m not surprised at all. Its still too new. Nobody makes flashlights that fit these cells yet. Sure you can put them in 26650 lights, but those batteries are 5,000 to 5,200 mah and cheaper as well.

It might be 6 months or a year when 20700 being sold in more stores and flashlights are made for them.

Shhhh…. don’t tell…… they are …THIS WEEK!!! P60…20700…… SECRET! :innocent: TL

What was that TL? I couldn’t hear you. :stuck_out_tongue:

Tom, you could send those 2 A’s over here and let me see what 3 50.2’s think of em… HKJ’s site shows they hold up better than virtually anything at a 30A drain, can’t find a 26650 cell that will best em. Can’t find 2 for myself anywhere either, at the moment.