Need a SAFE, large-capacity 26650 protected/unprotected cell (for low currents)

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cdm-dude

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I currently charge my phone (out in the field) with the Nitecore F1 charger/powerbank. I use it mostly as a powerbank and I feed it 18650 Fenix cells (3500 mAh), of which I always carry with me 2 or 3. Lately, my demands on the phone have increased and I am at a point where the capacity of 2 of those batteries isn't enough to get me through the day(s). I do not always have the 3rd 18650 battery with me, and when I do it is meant to be saved for something else. So, basically I need to add some power to my "power bundle" (it really is a bundle of all sorts of stuff). I sometimes use the F1 to charge other batteries, with the help of my Olight magnetic charger. Also, I can actually power up the F1 with four AA batteries (in series, a DIY rig) and charge the depleted 18650 batteries, plus my 14500 cells. As you can see, simply going for a dedicated PowerBank is not good idea for me, so, please, do not recommend any of those. My setup is very versatile and I can get power for my tech in all sorts of ways. At this time, I'm only looking to add a little more power to my kit. Instead of buying another Fenix 18650 (which would barely get me to where I need to be, if that), I figured I may as well get a 26650 cell instead. Since I've never owned one before, I feel that I should ask for advice. I apologize that this isn't (directly) flashlight-related.

My priorities are in this order:

1. Safety: The battery doesn't catch fire when in use or in storage.
2. Reliability: The battery doesn't just die on me for no reason.
3. Capacity: I need to get something that justifies the additional heft, when compared to a 18650/3500mAh cell.
4. Price is last: Not looking to save any money and I'll pay what I have to.

I have never bought an unprotected lithium cell. I do own a few unprotected 18650's but those were included with all sorts of tech I bought over the years. I almost never use them and I NEVER take them with me into the field.
The F1 charger (in the PowerBank mode) will shut down when the battery reaches 2.8 volts (it says so in the manual), so, I do not worry about damaging my new, unprotected 26650 cell that way, HOWEVER: another concern of mine is a short circuit scenario! What happens when water gets to an unprotected IMR battery? Does it catch fire and light up my whole backpack, to leave me stranded miles and miles from civilization, WITHOUT survival gear? (Just one example of water getting onto the battery: a leaky water bottle in the backpack, enough said). This has always been my no.1 concern with regards to all electronics that I carry with me into the wilderness.

So, after careful consideration, this is where I am right now:


The rated capacity is OK and the tested capacity is even better. They even provide a little Excel chart, which looks pretty sweet. TBH, after shopping around, I don't think that you can beat those specs in the "protected realm". However, there is one (and only) review by someone who claims that the tested capacity of this battery is 3890 mAh... Hmm...

I should also say that I am not planning to use my new 26650 battery for anything other than to charge my phone with (and possibly other tech too).

I measured the output of the F1 charger (in the powerbank mode), w. my Fenix 18650 in place. When charging my phone it is: ~5V, ~850mA. I figure that F1 draws right around 1A from the battery and bumps up the output voltage to 5V (USB specs), from the nominal 3.6V (or whatever) of the cell. As the 18650 approaches depletion, the current drops, obviously. Actually, I have not tested where things are at towards the end. I don't think that my Fenix's will allow themselves to be drained all the way down to 2.8 volts (at which point, even the F1 will shut itself off). Also, my phone stops charging itself once the input current drops below 200mA... hmm.. .. So, thinking about it, I don't really know whether all this time I've been fully utilizing my protected 18650 batteries. Does anyone know by any chance at which point the undervoltage protection kicks in with those babies?

At any rate, with the setup I have right now, the nominal charging current is right where I want it to be. At home I charge EVERYTHING at 500mA but in the field I need to be charging my phone a little faster than that, for as long as the power source can provide, anyway.

Sheesh!... over 800 words!... damn.

Any suggestions? Thanks!
 
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KITROBASKIN

KITROBASKIN

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cdm-dude

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Yeah, the 21700 is a big pill to swallow. The F1 is on the flimsy side, so I wouldn't want to force feed it anything either way (plus, that battery appears to be out of stock). The 26650, however, is exactly what I need! Haven't heard of that brand before but I would give it a go, EXCEPT, I am not in North America and I don't think those guys ship anywhere else. Li-ion batteries are problematic that way (because they are a fire hazard). I've always had good experience with Fasttech, and they were the only other place I looked, after not finding anything suitable on ebay. In fact, I think that I got the bulk of my Li-ion batteries from Fasttech. Naturally, I inquired about a product that they had available.

I think I might actually go for the: KeepPower ICR 26650, 5200 mAh (because Fasttech sell them)

There's a full review of this battery on candelpowerforums and the measured capacity appears to be almost right on the nose! I actually might order two.
 
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Hooked on Fenix

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+1 for the Orbtronic 26650 cells. Have to buy two minimum but price is good and so is quality. I use their 14500s, 18650s, and 21700s. Haven’t failed yet.
 
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cdm-dude

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I would buy two myself, except I can't get them shipped to me. Instead I'm going to order two KeepPower's, to have one for backup, in case 1 fails on me. If I knew there was a thorough review of KeepPower 5200 on candlepowerforums, I probably wouldn't even need to start this thread. Everything I need to know is in that review.
 
KITROBASKIN

KITROBASKIN

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I would buy two myself, except I can't get them shipped to me. Instead I'm going to order two KeepPower's, to have one for backup, in case 1 fails on me. If I knew there was a thorough review of KeepPower 5200 on candlepowerforums, I probably wouldn't even need to start this thread. Everything I need to know is in that review.
Yes Orbtronic not shipping internationally as I remember. KeepPower is ok but long time ago the width was excessive compared to others. Confirmed the Orbtronic protected in (I believe) a NItecore F1 charger:

Charger26650
 
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cdm-dude

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Wow, nice pic, man! That's my F1! However, I questioned the compatibility (sizewise) of the 21700 Orbtronics, not the 26650 which, according to the photo (and very unsurprisingly) fits into the F1 charger just fine. Moot point though, since I can't get my hands on either.

I was about to pull the trigger on a couple of KeepPower's 26650, 5200 mAh, from FastTech but ended up just missing the boat. They are not taking orders for the duration of the Chinese New Year's holidays. I can order the same product from AliExpress (most merchants there work through the holidays) but I am somewhat concerned (actually, scared), knowing that there are lots of counterfeits floating around. So, currently I am looking at all the options I would have, ordering from AliExpress. I really want to stay away from anything that is rated at 10Amps or above. I won't be drawing from the battery much more than 1A, ever (if that). So, all those low-internal resistance puppies spell for me just one thing: (unnecessary) Fire Hazard.
 
KITROBASKIN

KITROBASKIN

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Some good thinking there, though many members here shun protected cells. First time I held a 26650 there had been a report on CPF here about a fast burning 18650 some vapor person had in their pocket; store video caught the action and it was not pretty. The 26650 looks big, and the potential for catastrophe is rare but possible. Avoiding careless behavior seems key.

Years ago I ordered from FastTech with no problems but found the metal strip that runs along the cell of a couple protected KeepPower 18650 too proud for some flashlights. Have you considered Illumn? They are USA but I think they ship internationally. They also have replacement battery plastic shrink wrap sleeves that are a good idea to have when a wrapper on a battery gets damaged and really needs to be fixed.

I use mostly unprotected 18650's because of the flashlights used, but protected cells have never been a problem for me, used in SolarForce, EagTac, Convoy and NiteCore torches.

My NItecore F1 charger has been the primary stand-by charger when mobile since it came out.
 
KITROBASKIN

KITROBASKIN

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mtnelectronics is another great guy in USA that ships international. The EVVA brand has been just fine for me. Some countries have shipping restrictions for shipping batteries.
 
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cdm-dude

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Thanks man, I think I'll just order something from Ali. The shipping there is either zero or next to nothing, plus I've never ordered any batteries from the US (but have from China and Hong Kong). I wouldn't want to risk shipping from the US now, even if it was OK with the seller, not this time.

FYI: For all international orders, mtnelectronics refers you to their "international store" which does not offer any batteries at all! Yep, shipping batteries internationally is a headache everyone seems to want to avoid. It is a known problem.

PS: I loved the rest of the stuff that they have there, i.e. flashlight components. Not really a huge flashlight buff but nerdy enough that way. Bookmarked!
 
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