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DownEaster
08-02-2017, 12:33
I bought this Ultrathin 20000mAh Portable Power Bank (http://www.ebay.com/itm/Ultrathin-20000mAh-Portable-Battery-Charger-Power-Bank-for-Cell-Phones-HR/252514777145?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649%3E) (5.3 oz./151 g including USB-to-µUSB cable) on eBay. It's noticeably lighter than the Anker PowerCore 10000 (https://smile.amazon.com/Anker-PowerCore-Ultra-Compact-High-speed-Technology/dp/B0194WDVHI/ref=sr_1_1?ie=UTF8&qid=1501686871&sr=8-1&keywords=Anker+10%2C000+mAh), which at 6.35 oz./180 g was considered the "go-to" power bank among through-hikers just two years ago. It's way lighter than the similar-capacity Anker PowerCore 20100 (https://smile.amazon.com/dp/B00X5RV14Y?ref=emc_b_5_t) at 12.56 oz./356 g. And it's cheap: under $9 shipped.

My unit came in silver; they also make them in blue, pink, black, and gold (randomly distributed). The housing appears to be aluminum. Given the low weight and high capacity I'd guess they're using lithium ion cells. There is no documentation at all, so I fiddled with it a bit to deduce the how-to.

There is one button, between "ON" and "OFF" labels. When I pressed it 4 small blue LEDs came on to indicate that it was about 4/4 charged (presumably 17,500+ mAh). There's a µUSB port labeled "IN". I plugged the included cable into that port, with the other end in a USB port in my PC. Immediately the first 3 blue LEDs lit up steadily, and the rightmost one started blinking to indicate that it was charging the last 1/4 of its capacity. There are two USB outputs, one labeled "OUT 1A" and the other labeled "OUT 2.1A"; I should be able to charge my phone and headlamp simultaneously. I don't know if this power bank supports powering other devices while it's being charged, but that's not a big concern because I've got a 4 USB port AC adapter so I won't need to do any daisy-chaining when I've got electrical outlet access.

There's no mention of "Quick Charge" or other such technology, so presumably charging won't be fast. Of the three prime metrics of backpacking technology (Light, Cheap, Good/Fast) I'm happy with the two I got here.

DownEaster
08-02-2017, 12:38
Here are a couple of pictures:
40005 40006

The Kisco Kid
08-02-2017, 12:52
It's also a generic unit shipped from Malaysia whereas Anker is a US-based company that offers an 18-month warranty and a thousand positive reviews on Amazon. If your unit fails, you're carrying 5.3 ounces of garbage. And 20,000mAh is overkill in my book (actual testing would likely prove this claim to be highly overstated).

I can make it 5 days easily without recharging my iphone (airplane mode with limited picture taking).

The Anker Powercore 5000 (https://www.amazon.com/Anker-PowerCore-Ultra-Compact-High-Speed-Technology/dp/B01CU1EC6Y/ref=sr_1_10?s=wireless&ie=UTF8&qid=1501692053&sr=1-10&keywords=anker+power) charges an iphone twice for 4.8 ounces. I have the 3350 mini, but don't carry it.

Slo-go'en
08-02-2017, 13:36
A 20 Ah rating for a battery that small and light would be an incredible power density. More of a bomb then a power pack. I bet the true capacity is 1/4 of that and even that might be overly optimistic.

Maineiac64
08-02-2017, 13:41
Wow, great find. Let us know how it works in the field.

DownEaster
08-02-2017, 13:50
@Kisco Kid:

I've got a Moto G4 with a 3000 mAh battery. My Vansky headlamp has a 1200 mAh battery. I don't know what the capacity is on my $8 backup/belt-mounted light, but one full night of hiking with GPS navigation is likely to use more than 5000 mAh. I'm glad to have this as an option if the forecast is for a clear night followed by a day of rain.

If I were to carry an Anker power bank and it failed, I'd be carrying garbage -- with a chance to replace that garbage with a functioning power bank at some time in the future, via a procedure that's quite difficult to comply with if you're on the trail. The seller I bought this from has over 29,000 reviews with a 98.7% positive rating.

If you don't like this product because it comes from Malaysia, then you certainly shouldn't buy it. However, you're implying that the quality is poor without any evidence, and also that the very efficient power-to-weight ratio doesn't matter. I think you'll find a lot of backpackers would disagree with you.

DownEaster
08-02-2017, 14:02
A 20 Ah rating for a battery that small and light would be an incredible power density. More of a bomb then a power pack. I bet the true capacity is 1/4 of that and even that might be overly optimistic.
I don't think the seller would have maintained their reputation if they sold 5000 mAh advertised as 20000 mAh. This is small by power bank standards, but the case still has enough volume to hold 8-10 of the 3000 mAh batteries used in my Moto phone. There's been so much production of lithium ion batteries that the technology has improved dramatically over the last few years. What I don't expect out of this power bank is speed. Delivering power at too great a rate (relative to what production line quality control allowed) was the problem with Samsung Galaxy Note 7 battery fires. I expect recharging to be an overnight affair.

HooKooDooKu
08-02-2017, 14:05
A 20 Ah rating for a battery that small and light would be an incredible power density. More of a bomb then a power pack. I bet the true capacity is 1/4 of that and even that might be overly optimistic.
That's pretty much exactly what I was thinking when someone tries to compare a no-name battery pack to an Anker.

If a 20Ah Anker battery weighs 12.5oz, TNFW a no-name battery weighing only 5.3oz is going to come close to true 20Ah usable capacity.

HooKooDooKu
08-02-2017, 14:19
I don't think the seller would have maintained their reputation if they sold 5000 mAh advertised as 20000 mAh. This is small by power bank standards, but the case still has enough volume to hold 8-10 of the 3000 mAh batteries used in my Moto phone. There's been so much production of lithium ion batteries that the technology has improved dramatically over the last few years. What I don't expect out of this power bank is speed. Delivering power at too great a rate (relative to what production line quality control allowed) was the problem with Samsung Galaxy Note 7 battery fires. I expect recharging to be an overnight affair.
First of all, most of the general public doesn't know what 20000 mAh even means... the only way they would know if they have been taken is if they did a side-by-side comparison with a battery pack that can truly deliver 20000mAh of capacity.

But even if you are right about capacity and charging rate, then you're way off on how long it takes to charge the battery. I believe today's standard is that a "standard" charger can provide 0.5A of current, and a "quick" charger provided 2.0A or more. At 0.5A, it would take 40 hours to deliver 20000 mAh to the battery pack... and that's if the charging was 100% efficient. So if the battery can't take a rapid charge, then you're looking at two DAYS to recharge this battery, which means it's not good for a thru-hike unless you like hiking a 5 day hike week.

DownEaster
08-02-2017, 14:23
If a 20Ah Anker battery weighs 12.5oz, TNFW a no-name battery weighing only 5.3oz is going to come close to true 20Ah usable capacity.
You're comparing Anker's 3-year-old design (guestimating from early 2015 Amazon reviews of the PowerCore 20100) to something that only started selling on eBay recently. The Anker uses 6 18650 Panasonic 3400mAh batteries - NCR18650B, and there are better batteries available today.

Starchild
08-02-2017, 14:23
I also question the power rating on that unit, but that does not mean it's a bad buy, it might be very good even if lower than advertized.

Funny thing about Li-ion batteries you can get a lot more power out of them then most manufacturers will allow. Li-ion is artificially limited in how full it can get and how low it can get (false 0% and false 100% state of charge). This is because if they use the true 0% and true 100% you expose the battery to conditions that will greatly shorten it's life. (it's also the reason it's not good to leave laptops plugged in all the time, as you approach the fully charged limit it does eat away the life, just not as fast as true 100%). Some no name manufactured push these limits and as such get many more mAh out of the batteries, but also dramatically shorten the life.

IDK if they one you got does this or not, I've had both, and I have had very good luck with a 'no-name' battery pack that seemed to deliver over many years.

As for Anker, they seem to be a good company that would not monkey around with the limits to extend run time (though not no one has stated how their customer service is, no less on trail), however 'American made' does not equal quality, in some ways we have sadly lost manufacturing quality, and there is the American profit motive which drives prices up, riding on patriotism which masquerades for quality.

Gambit McCrae
08-02-2017, 14:24
Gambit is a firm believer in you get what you pay for. Proves itself time after time. I have been down the "cheap 20,000 mah power bank" Trail, And after night 1 it was dead. Big ol 18$ hunk of crap.

I carry an anchor now, and have ben quite pleased. Got it on amazon for a good deal. $48 bucks or so. I use my phone like its going out of style, music - videos - texting - calling - pictures - guthooks...its used on and off all day long on the trail. So I have a pretty solid battery bank, but its not even 20 mah.

DownEaster
08-02-2017, 14:27
But even if you are right about capacity and charging rate, then you're way off on how long it takes to charge the battery. I believe today's standard is that a "standard" charger can provide 0.5A of current, and a "quick" charger provided 2.0A or more.
This isn't a "quick" charger, but it's labeled "INPUT DC 5V, 1.5A (max)". So 3X as fast as your low end estimate.

HooKooDooKu
08-02-2017, 14:40
You're comparing Anker's 3-year-old design (guestimating from early 2015 Amazon reviews of the PowerCore 20100) to something that only started selling on eBay recently. The Anker uses 6 18650 Panasonic 3400mAh batteries - NCR18650B, and there are better batteries available today.
One of Anker's latest releases is a 10,000mAh battery pack that weighs 7.4oz. Based on review days, I'd say the battery was released in May of this year.
This Malaysian battery is claiming twice that capacity for 30% less weight.

"If it's too goo to be true, it probably is"

That phrase fits battery packs just as well as everything else in life.

MuddyWaters
08-02-2017, 14:43
Nope
Cheap batteries are notorious for being under capacity

Everybody know that

DownEaster
08-02-2017, 14:57
From what I can tell, Anker is still using cylindrical cells in their battery packs, whereas newer batteries like the one in my phone are flat. There's more casing overhead (weight) in cylindrical cells.

MuddyWaters
08-02-2017, 15:16
From what I can tell, Anker is still using cylindrical cells in their battery packs, whereas newer batteries like the one in my phone are flat. There's more casing overhead (weight) in cylindrical cells.

Actually no.
Thin and flat results in larger surface area to volume ratio.ie..more casing material required

I have a flat, lightwt , lipo battery pack. It weighs 3.25 oz , 4000 mah.

soumodeler
08-02-2017, 15:36
Anker is pretty much the gold standard when it comes to power packs. They have a well deserved reputation for quality.

There are a couple of things to question with this battery: the true capacity (which would be hard to measure), the efficiency (basically, you lose part of the stated capacity to heat when using the battery to charge another device. Most Anker batteries lose 15-20% when charging, cheaper packs can lose up to 50% and sometimes more), the quality of the circuitry (you risk frying the battery components and even the device you are charging), and the rate of charge.

The only way for you to really tell would be to take a device with a known battery capacity (google is your friend) and after fully charging the battery pack, completely discharge and then recharge that one device from the battery pack until the battery pack is out of juice. You can make an educated guess about capacity and efficiency at that point, and more importantly, tell if this particular battery pack meets your needs for charging on the trail.

I know you think you found a good deal for an ultralight battery pack, but there are a lot of factors stacked against you. eBay is not known for being a place to buy quality electronics. Ultralight and cheap do not go together 99% of the time.

Hopefully it works for your needs. Best of luck!

The Kisco Kid
08-02-2017, 15:38
@DownEaster

Your avatar says you're a thru-hiker in planning. Folks are trying to be helpful here. I wouldn't take it personally (unless you invented this battery :))

#1 - the failure rate for this power pack is likely to be high. It's just too good to be true. A 98.7% positive feedback on eBay is not so good. Feedback on eBay is highly overrated. I recommend opening up the seller's feedback page and then clicking on the negative feedback ratings. You'll be able to read the 381 negative feedback comments this year, including: "Real measured capacity liitokallaa only 450-500 mAh!!!cheating! 12 times LEss!!!" for another battery from the same seller.

#2 - you likely won't need all that storage power the way your describing your potential usage. The Vansky headlamp you mentioned has rechargeable batteries. For $9.99 it will likely fail and the batteries will run out of their charge when you least expect it. When you're in the backcountry stay away from rechargeable batteries if you can. Here's the Petzl E+LITe headlamp (https://www.amazon.com/Petzl-Headlamp-Lumens-Ultra-Light-Compact/dp/B01MZ4TOY4/ref=sr_1_1?ie=UTF8&qid=1501702575&sr=8-1&keywords=petzl+elite) I've used for years. Weighs 1 ounce. The Vansky headlamp weights 2.5 oz. + cords and you need a heavier power pack to keep the thing charged. You mentioned hiking with GPS navigation? Navigation is a non-issue on the AT. (The CDT is a different story.) The AT is so well marked, most hikers don't even carry a map and compass. Here's the 0.2 compass (https://www.rei.com/product/857612/suunto-clipper-l-b-nh-compass) I carry.

On the trail it's not about the latest technology, but what is proven to function when you need it most. Have fun planning your hike and happy trails!

Another Kevin
08-02-2017, 15:46
I think I'll keep carrying my 16000 mAh pack for a while yet, even if it is the approximate size and weight of a brick. The input is rated at 2.2 A and it takes overnight to charge. It'll keep my gadget running for as long as I want to carry the food for - but just barely.

I'd actually be worried about some of the knockoff brands catching fire. Big LiPo packs are kind of explodey,

MuddyWaters
08-02-2017, 15:55
Anker is pretty much the gold standard when it comes to power packs. They have a well deserved reputation for quality.

There are a couple of things to question with this battery: the true capacity (which would be hard to measure), the efficiency (basically, you lose part of the stated capacity to heat when using the battery to charge another device. Most Anker batteries lose 15-20% when charging, cheaper packs can lose up to 50% and sometimes more), the quality of the circuitry (you risk frying the battery components and even the device you are charging), and the rate of charge.

The only way for you to really tell would be to take a device with a known battery capacity (google is your friend) and after fully charging the battery pack, completely discharge and then recharge that one device from the battery pack until the battery pack is out of juice. You can make an educated guess about capacity and efficiency at that point, and more importantly, tell if this particular battery pack meets your needs for charging on the trail.

I know you think you found a good deal for an ultralight battery pack, but there are a lot of factors stacked against you. eBay is not known for being a place to buy quality electronics. Ultralight and cheap do not go together 99% of the time.

Hopefully it works for your needs. Best of luck!
Its not hard to discharge slowly with essentially constant current and time it. Use simple resistor , current will vary a little as voltage changes , but you can take average. Easy to build current regulator with radio shack chip too.

I used to charge and monitor and chart battery packs for radio control aircraft tx and rx,.

HooKooDooKu
08-02-2017, 16:53
From what I can tell, Anker is still using cylindrical cells in their battery packs, whereas newer batteries like the one in my phone are flat. There's more casing overhead (weight) in cylindrical cells.
Perhaps true, but the point is irrelevant.

The bulk of the weight in these battery packs is going to be in the batteries and not the case.

Add to the the fact that my latest comparison to the 20000mAh Malaysian battery was to an Anker 10000mAh battery and the deal still sounds too good to be true.

Puddlefish
08-02-2017, 17:02
I'd just wait for some electronics geek to put it on his workbench and do the testing. Yay for geeks!

cbxx
08-02-2017, 17:10
One way to answer all these concerns concretely, start using the battery and see what it can do. Use it a couple weeks and report back please because if it does what is advertised, it would be a great improvement, but we would need proof. Anker has a reputation, this is a new deal so please do report back.

Slo-go'en
08-02-2017, 17:44
The capacity of a battery is directly related to the surface area of the "plates" which make up the battery. A round battery is simply a flat battery which has been rolled up. The only difference is shape. The volume and capacity stay the same.

Anyway, despite this thing is unlikely to live up to it's spec's, it's still useful and it didn't cost you much. The "how many times can it charge my phone from 10% to 100%" is a good test.

Another Kevin
08-02-2017, 17:47
The capacity of a battery is directly related to the surface area of the "plates" which make up the battery. A round battery is simply a flat battery which has been rolled up. The only difference is shape. The volume and capacity stay the same.

Anyway, despite this thing is unlikely to live up to it's spec's, it's still useful and it didn't cost you much. The "how many times can it charge my phone from 10% to 100%" is a good test.

Assuming that they didn't cheap out on the charge controller. The case that scares me is that it's close to being true to rated capacity but has a crap controller and goes up in smoke. 20 Ah of lithium battery makes a LOT of smoke.

Riocielo
08-02-2017, 20:21
It's also a generic unit shipped from Malaysia whereas Anker is a US-based company that offers an 18-month warranty and a thousand positive reviews on Amazon. If your unit fails, you're carrying 5.3 ounces of garbage. And 20,000mAh is overkill in my book (actual testing would likely prove this claim to be highly overstated).

I can make it 5 days easily without recharging my iphone (airplane mode with limited picture taking).

The Anker Powercore 5000 (https://www.amazon.com/Anker-PowerCore-Ultra-Compact-High-Speed-Technology/dp/B01CU1EC6Y/ref=sr_1_10?s=wireless&ie=UTF8&qid=1501692053&sr=1-10&keywords=anker+power) charges an iphone twice for 4.8 ounces. I have the 3350 mini, but don't carry it.

And Anker has tremendous customer service, too.


Sent from my iPad using Tapatalk

Starchild
08-02-2017, 21:00
Its not hard to discharge slowly with essentially constant current and time it. Use simple resistor , current will vary a little as voltage changes , but you can take average. Easy to build current regulator with radio shack chip too.

I used to charge and monitor and chart battery packs for radio control aircraft tx and rx,.

Yes but...
Can it deliver time and time again??? Some Li-ion batteries can deliver early in life but only live a quick life.

scope422
08-02-2017, 21:13
I'll add my 2 cents on this one. I've been using this battery bank for over a year now. I like it but I usually only do 3-4 day trips at a time. I tested it's capabilities at home and here's what I found. With a Galaxy S5 phone, I let it go till it went dead. Got 1 full charge to 100% and then ran phone dead again and got 70 percent on 2nd charge before battery bank died. This battery bank does take about 6-7 hours to charge back up again from dead. I never run my phone to dead, lots of airplane mode, so it's always had sufficient power to get me through long weekends. Also, you can find US sellers selling this same battery on Ebay for the same price, so you don't need to wait for overseas shipping.

HooKooDooKu
08-03-2017, 00:26
I'll add my 2 cents on this one. I've been using this battery bank for over a year now. I like it but I usually only do 3-4 day trips at a time. I tested it's capabilities at home and here's what I found. With a Galaxy S5 phone, I let it go till it went dead. Got 1 full charge to 100% and then ran phone dead again and got 70 percent on 2nd charge before battery bank died. This battery bank does take about 6-7 hours to charge back up again from dead. I never run my phone to dead, lots of airplane mode, so it's always had sufficient power to get me through long weekends. Also, you can find US sellers selling this same battery on Ebay for the same price, so you don't need to wait for overseas shipping.
That sounds about like the performance I would expect from a 6700mAh Anker battery that weighs about 4.5oz.

Starchild
08-03-2017, 08:28
The charging time of the battery seems a little slow, and on trail you might have limited access to an outlet and want to cram as much juice in as you can. Other then that it seems like a good value and certainly good enough for weekend warriors and even week long trips with limited use of the phone.

MuddyWaters
08-03-2017, 08:38
Yep
Recharge time is issue if use lots of power
Better with two smaller batteries for that

My 10,000 anker can take 8 hrs to charge, overnight badically. Not going to recharge at quick resupplies.

My phone has little battery, but for even 6-7 day stretches taking 20 pics per day, reviewing, airplane mode, etc Ive not used more than half the anker in recharging. Cant umagine needing more. most time i bring my little 4000 3.25 oz battery , it lasts me week basically if careful.

DownEaster
08-03-2017, 11:15
The charging time of the battery seems a little slow, and on trail you might have limited access to an outlet and want to cram as much juice in as you can.
I agree completely. That's why I've got a 4 USB port AC adapter so I can charge up the power bank, my phone, and both headlamps simultaneously. With that approach I shouldn't need to draw down the power bank's charge for at least a couple of days. I'd expect to have at least 3 hours connected to power outlets while I'm doing laundry and eating a meal. ("Table by a wall socket, please." ;)) Or if I don't need to charge up the headlamps, I can gain some hiker goodwill by sharing the outlet.

Starchild
08-03-2017, 12:03
I agree completely. That's why I've got a 4 USB port AC adapter so I can charge up the power bank, my phone, and both headlamps simultaneously. With that approach I shouldn't need to draw down the power bank's charge for at least a couple of days. I'd expect to have at least 3 hours connected to power outlets while I'm doing laundry and eating a meal. ("Table by a wall socket, please." ;)) Or if I don't need to charge up the headlamps, I can gain some hiker goodwill by sharing the outlet.

Having a multiple USB charger is a good thing on trail and I have used that also. But other times when I know I'm going to be in town I will charge my phone and steripen before I get there. This way I only have to leave a battery pack unattended to charge. And that ability to leave it unattended usually results in a longer uninterrupted charge time and perhaps more overall charge. I actually prefer that second option over having to hover over my phone tethered to a wall outlet, which out of boredom I use and thus make charge time longer. But yes restaurants, everything charging at once with the table by the outlet please.


Also I do play the state of charge knowing that the quickest and most efficient charge is apx from 25% to 80%, dip far below 25% and you wait a long time to get back up to it likewise getting that last from 80% to 100% takes longer and is less efficient, so when multi charging I try to keep the items balanced within those limits so they can accept the most charge in the least time (also knowing that using a battery pack to charge another device is about a 20% loss, but that charge is still more efficient in that 25% to 80% range, so not topping off the phone to 100% unless I am using that plan to leave the battery pack unattended to charge).

Another Kevin
08-03-2017, 12:29
That sounds about like the performance I would expect from a 6700mAh Anker battery that weighs about 4.5oz.

Yup. No way is that a 20 Ah pack. I get more like 3˝ charges on my S7 using a 12 Ah pack (I misremembered yesterday when I quoted '16 Ah'.) It's NewTrent, rather than Anker, because when I got it, it was the only one I could find that was IP68. I'm hard on gear. NewTrent went out of the battery business shortly after I got it. The Anker ones of comparable rating are lighter now, but I don't fix what ain't broke.

Leo L.
08-05-2017, 04:57
Just recently there was a good test report about powerbanks in my favorite computer magazine.
While it doesn't cover Anker products, it still unveils some typical, hmmm, misunderstandings, or you may say, ways of cheating around powerbanks.

First, the numbers for mAh on the powerbank are the numbers for the cells itself, and do not count in the voltage (which usually is 3,6 or 3.7V).
The output on the plug is around 5V (and more, if Quickcharge or similar), and to come from 3.7V to 5V (or more) you need a step-up converter amongst others, and this electronics might have an efficiency of 60-70%. By just telling you the cell capacity, the manufacturer keeps the real output a secret.

Second, LI-cells are very sensitive around zero and 100% charge, both states can damage the cells pretty fast.
In high-end products a clever electronics keeps the operating range off these dangerouse states by a certain margin, by this limiting the real-life capacity by a certain percentage, in order to achieve a better life span of the product.
When a manufacturer is boasting very high capacity for low weight and small dimensiones (and still doesn't outright lie about the sheer numbers), most likely no such measures are taken, and the pack might lose a lot of its capacity after a few times of use - given that the operator doesn't keep the pack strictly within a, say, 20-80% charge state.

During my desert hike this spring I carried two powerpacks, my good old Varta 6000, and a borrowed brand-new noname 10.000.
While my Varta, now 3yrs old, still can charge my smartphone 2.5 times, the noname 10.000 could fill it 1 time and after this just gave me blinking LEDs.

BTW, in the above mentioned test report, all 5.000mAh powerbanks weighed in about 150-200grams, the 10.000mAh 250-300grams, and the 20.000 were about 450-500grams.
The difference in weight per category correlates with additional features, like solar cells (which are completely useless BTW, and make a 10.000 pack 300grams instead of typical 250), and sturdy/waterproof case etc.
The weight of the cells itself seems to be quite a fixed number. This mages it pretty much impossible for a 20.000mAh pack to weight in at only 151g.

Gabigabs
03-27-2018, 23:14
Sounds like a great deal. We carried the Anker because of its weight and reliability. We were very happy with it.

Cheyou
03-28-2018, 05:54
http://charger.nitecore.com/CHARGER/F/F2/
Bring as many batteries as you need
thom

Crossup
03-28-2018, 11:40
A LOT of guessing and assumptions in this thread.
I fly R/C model planes and we have been using Lithium ion family cells/batteries as long as they have been used...I literally own hundreds cells of all ages and several (lithium)chemistries and have pushed them to their limits.
NOTE: cells are individual "batteries" which can be added together to make different capacity/voltage batteries. Lithium chemistry cells provide a nominal 3.7volts with 4.2v being fully charged. Cell phones use a single cell, lights and other devices may use several cells to provide either more capacity or voltage or both.

A lot of these power packs use the 18650 cell but there is no hard reason why they should beyond cost as there are several traits which make Lithium Polymer cells a better choice.
The 18650 is one of the oldest cells out there yet somehow is still a favorite...ask Tesla why they use them. There have been no dramatic improvements in these but capacity has crept up continuously...early cells(circa 1995) were pretty low, IRC sub 2000mah...current cells are now topping 3900 mah. They are good cells for many apps but worthless for high discharge compared to current Lithium Polymer cells.

Lithium polymer(LiPo) batteries on the other hand have evolved a good bit faster and while the bulk of the improvement has been toward improved(even monstrous) discharge ratings and faster charging along with longer cycle life, the basic power density has not changed a lot. To me, the big advantage to LiPo cells is they are packaged in a plastic film significantly decreasing weight while also allowing the packaging to be nearly any shape. The down side is they must be protected from physical trauma unlike the fairly robust metal cased 18650 type.

Of course there are a lot of factors involved but first off lets consider this: with 18650s you can only pack round cells so close and with the capacity "fixed" by the standard size of them, overall capacity for a given volume is always going to be a good deal lower than a single cell LiPo.
I'd guess a 20k mah LiPo pack could be 25% smaller compared to 18650s. Weight wise LiPo also trumps the 18650 but bottom line a 20k mahLiPo is going to have a bare cell weight of around 350 grams.

A few facts about Lithium Polymer batteries- they have a life of approximately 1000 cycles but that can be shortened by many factors- I'll list the main ones. When they approach their cycle life they loose capacity increasingly.
1) Deep discharge- you can take them down to 3.0volts without real damage and many applications allow that...stopping early helps cell life but costs you capacity use. Ideally 3.3v is a good lower limit.
2)Storing fully charged- that will cut years off their (including shelf) life which is very long. A very low self discharge rate being a huge benefit of Lithium cell tech. Manufacturers recommend storage voltage of 3.8v versus the 4.2v a full charge provides. Modern high discharge rate cells can be significantly damaged with full charge storage in only a few years.
3)Fast discharge- cells are all rated to be discharged as multiples of the capacity ie: a 20k mah cell maybe rated "10C" which means you can pull current out at 10 x 20k ma(ma=milliamp or 20 amps in this case) or 200 amps total- that will start you car if you series 3 cells to get 12volts. Discharging at the rating will cut life dramatically, going over the rating can cut it down to a handful of cycles. In general for charging other devices this should never be an issue, charging your phone off a 20k mah pack is only 0.1C. Even garbage cells can handle 1C discharges so again, should be no issue for the intended use.
4)Fast charging- most cells are rated 1C charging or put another way, a one hour charge rate. We now have cells that can handle 10C(6 minute charge) but obviously its hard(and dangerous, fire wise) on a cell to push its temps to the limit which fast charging does. Charging and discharging are both limited by the cells internal resistance and the push is to lower that to improve performance and efficiency along with safety.

I'll be glad to answer any questions if any of this is not clear or complete enough.

Crossup
03-28-2018, 12:01
Not stated here but the vast majority of power pak manufacturers DO NOT make the cells... my assumption would be if they dont state they do, then they dont. The fact that this useage is very easy on cells means there are a lot of opportunities to cut costs with older, low performance cells and a poor cost-benefit ratio for using premium cells. So researching for test data is not only a good idea but perhaps the only way you can find out ahead of time if a pack will or wont last long term

fiddlehead
03-29-2018, 06:07
About a year ago, I bought the Anker IQ It is 5000 mAH I believe.
I got it because of reviews on here and PCt-l.
I was shocked at how heavy it was so, didn't take it on my hike last summer (52 days in eastern Europe)
I took instead a Goal Zero Flip 10 that a hiker had left at my house by mistake. 2700 mAH
It is (guessing here) 1/4 of the weight of the Anker and it definitely gave my phone at least one full charge (don't let it go to zero so, really I felt I got about 1 1/2 charges out of it.
With the Anker, I get about the same (1 to 1 1/2 charges on my phone)
So, I don't understand the hype about Anker for hiking.
It seems very heavy (I'd guess 5 oz?) and doesn't seem to give much charging power.

Does anyone have experience with this Goal Zero Flip 10 power bank?
It is now 2 years old and I'm going on a hike in 2 weeks. (Tazmania), so, I'm wondering if I should rely on a 2 year old power bank.
It seems like it still works well.
I see they are about half the price of the Anker I bought.
Is Anker really all is cracked up to be?
I'm not impressed. anyway.