Official Owners Thread : TQKA 20,000 mAh LiFePO4 Battery

Reeflekt

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I bought it today, there was only one available. I should get it somewhere next week. I'll let you guys know if I'll receive the same unit, sometimes the sellers messing up the listing.
Thanks for a quick reply and explanation.
 

Dashmellow

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Since early July, and now, the Amazon page for that unit not only says "Currently unavailable" but there are no and have been no "Add to Cart" or "Buy Now" buttons to click on. It is a mystery why they would suddenly have a single unit in stock after all this time.

So, yes, please let us know what shows up.
 

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Sorry I couldn't reply sooner. It's been a very busy day and I knew this would be a long post.

So, to answer your question, as far as I can tell, the cells in both of the TQKA LIFePo4 power banks I've had trouble with are fine. I believe there is something wrong with the circuit that monitors and displays the remaining current as the power banks are draining down.

You may recall that the first one worked fine for a year and a half and then failed three days after the warranty expired. No matter what state of charge or discharge the unit was in, the read-out was stuck at 96. As you may also recall, TQKA was nice enough to offer a refund of half what I originally paid and I put the money into a new one as a replacement.

So, I was happily using the new TQKA unit I purchased at the end of June but then I began to notice a serious problem. If the unit was fully charged and reading 100% and I would plug in two of my dash cams and go shopping for a while I would come back to my truck to find the read-out down to around 25% or even much less!. I found I could literally sit in my vehicle and watch the power bank numbers dropping like a stone.

With the original TQKA power bank an hour or so of running a couple of dash cams would drop the counter only a few percentage points, about the same as any 20,000mAh power bank. A power bank of this size should run two dash cams for an entire day but the new unit loses the charge VERY quickly, like down to as much as 10% within maybe an hour or two. And then a weird thing happens. Once it drops to 10% it will continue to power my dash cams for many hours and still read 10%! When I get home I can charge the unit right back to where it reads 100% and everything about the charging process seems normal. At first, I thought the unit had some bad cells but it seems that the cells are fine and holding an adequate charge. I have yet to try draining it down all the way and see just how long it will really go with the read-out at 10% but soon I plan to do that when I have the time.

In the meantime, something weird also happened with my other original TQKA power bank, the one that was stuck at 96 for several months. At first, I took it out of service out of an abundance of caution but since LIF4Po4 cells are not prone to thermal runaway and it appeared to be accepting and holding a full charge I decided to continue using it as an experiment even though the read-out was stuck at 96.

Amazingly, after a couple of weeks of using it like that I came back to my truck one day after leaving it in "parking mode" running two dash cams for a couple of hours and the read-out now said 87%!. It came unstuck! For the next several hours it slowly drained down as one would expect and over the next few days after a few charge/discharge cycles the thing started working normally again. Never seen anything like it. It's good as new and the unit is 20 months old now.

So, my hunch is this sort of problem is a pervasive issue with these TQKA banks and it may explain why these units never came back in stock on Amazon.

Aside from this, until the latest developments I've definitely considered scavenging the cells from the power banks. I've opened up and removed the cells from a couple of Li-ion 18650 cell power banks and while it can be challenging it's not all that hard to do. Most power banks I've owned are a clam shell design with two halves sonically welded together.

This TQKA bank may also be a challenge because of the design (a solid aluminum tube with difficult to access end caps). It looks doable though. I think I may have to drill a small hole to create a grab point and then work a knife or spudger around the edges and try to pull the end cap off. It definitely doesn't look like an easy job. I'll see how things progress from here and come winter when I have more time for projects like this I will see about dismantling the unit. On the other hand if the bank is really taking and holding a full charge but only the read-out is funky I may just leave it alone and just use the power bank as a back up.
 
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Reeflekt

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I received my order and its indeed the TQKA 2000 mah LIFEPO4 power bank "Pentagon". It arrived in the sealed cardboard box with a pouch, a usb cord and the instruction. It came in pre-charged state and shows 89% remaining.

Can I start using the power bank out of the box or should I fully charge it?
20191002_113304.jpg20191002_113320.jpg
 
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Dashmellow

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I'm glad you received an actual "Pentagon" model, although I'm still puzzled why the are still listed as "unavailable" on Amazon. Hope it works properly and continues to do so.

You can start using it without charging. In fact, from my experience with lithium power banks, it is often a good idea to drain them down fully and then give them a full charge two or three times in the beginning. For reasons, I don't fully understand various lithium battery types need to go through several full charge cycles before they accept and hold a proper charge. Lithium batteries are said to be a bit like muscles that need to get some exercise now and again, especially after being in storage for a while or when new. After that it is best to not allow the lithium power banks to drain all the way and to try to keep them topped off and definitely try to charge them when they get down to 50 or 60%, if possible. As far as I know this applies to LIFePo4 as well as Li-ion. Supposedly, this will provide the best performance and longest lifespan.
 

EsQueue

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I'm glad you received an actual "Pentagon" model, although I'm still puzzled why the are still listed as "unavailable" on Amazon. Hope it works properly and continues to do so.

You can start using it without charging. In fact, from my experience with lithium power banks, it is often a good idea to drain them down fully and then give them a full charge two or three times in the beginning. For reasons, I don't fully understand various lithium battery types need to go through several full charge cycles before they accept and hold a proper charge. Lithium batteries are said to be a bit like muscles that need to get some exercise now and again, especially after being in storage for a while or when new. After that it is best to not allow the lithium power banks to drain all the way and to try to keep them topped off and definitely try to charge them when they get down to 50 or 60%, if possible. As far as I know this applies to LIFePo4 as well as Li-ion. Supposedly, this will provide the best performance and longest lifespan.
When I say Lithium Ion, I am referring to LiCoO₂ LiMn₄O₂ and LiNiMnCoO₂ cylinder batteries. When storing lithium ion for some time, never keep it topped off. Better 3.7ish. Many of the data sheets I've studied lists that the batteries are rated to handle anywhere from 300 - 2000 cycles. Usually, the longer they last, the lower the energy density of the cell. This is typically a full 4.2 v charge and a 2.50 - 3.00 volt discharge. Don't drain a Lithium Polymer cell lower than 3.0 volt though. Lithium Ion cells love the partial charge and discharge cycles it documented that this can expand their life cycles by as much as 4 times their rated. Lithium ion differ from NiCad and NiMh cells, draining and fully charging them is just a waste of energy. Some Chinese manufacturers list this in their instructions but they usually sell rebranded cells that do not perform at its advertised specs. LiFePO4 does its own things and holds less capacity but is much safer and uses different voltages too.

I've heard some say that it is a good practice to fully charge and fully discharge a power bank to calibrate their capacity display gauge. It makes sense if it checks and calculates the current voltage and both total input and output current.
 

Dashmellow

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When I say Lithium Ion, I am referring to LiCoO₂ LiMn₄O₂ and LiNiMnCoO₂ cylinder batteries. When storing lithium ion for some time, never keep it topped off. Better 3.7ish. Many of the data sheets I've studied lists that the batteries are rated to handle anywhere from 300 - 2000 cycles. Usually, the longer they last, the lower the energy density of the cell. This is typically a full 4.2 v charge and a 2.50 - 3.00 volt discharge. Don't drain a Lithium Polymer cell lower than 3.0 volt though. Lithium Ion cells love the partial charge and discharge cycles it documented that this can expand their life cycles by as much as 4 times their rated. Lithium ion differ from NiCad and NiMh cells, draining and fully charging them is just a waste of energy. Some Chinese manufacturers list this in their instructions but they usually sell rebranded cells that do not perform at its advertised specs. LiFePO4 does its own things and holds less capacity but is much safer and uses different voltages too.

I've heard some say that it is a good practice to fully charge and fully discharge a power bank to calibrate their capacity display gauge. It makes sense if it checks and calculates the current voltage and both total input and output current.
Yes, I agree. I was only talking about "topping off" if the battery is in regular use. Lithium-ion batteries should be stored at about a 40% state of charge. If you look back through this thread I mention and refer to most of the same points you make here.

It's also true that li-ion batteries should definitely not be drained lower than about 2.5-3 volts, as you say. As for discharging li-ion power banks, (or protected cells) you can drain them down "all the way" because the circuitry will cut off the discharge at the correct low voltage.

It's interesting about discharging and charging power banks for the first few cycles. When I purchased my first power bank about five and a half years ago many people on Amazon were complaining that the bank wouldn't hold anywhere near the rated charge claimed for it. Many returned them. I noticed this too the first time I used it. However, this particular power bank ( a Chinese 20,000 mAh generic) came with a small card in the package that advised the buyer to fully drain and then fully charge the bank for the first three cycles. I was skeptical when I first heard about this because it seemed to make no sense. Nevertheless, I went ahead and tried this and was astonished at the change in performance. Suddenly, the bank came to life and started performing really well and it would hold a charge under load for extremely long periods of time; basically performing according to its specs. Maybe it was just recalibrating but compared with other devices I own this felt different. And I wonder why if it was just a calibration they would recommend doing it three times in a row. Anyway, the bank lasted about five years in nearly daily use running two dash cams simultaneously and in fact is still functional, although at this point it probably has about 1/3 its original capacity. It sits on the shelf at about 40% charge.

So, I don't really have an explanation for why cycling the power bank for the first three cycles made such a difference but I recall seeing a reference somewhere to the notion that lithium batteries like to get cycled after long periods in storage. I think it was on Battery University. I'll see of I can find it.

I also agree with you about not fully charging lithium batteries. My understanding is that they should be charged to about 85%. Truth be told I often just let the banks I use charge fully because in my experience with quite a few of them now they last many years with excellent performance and are really quite inexpensive to replace these days. The most recent TQKA 20,000 mAh LiFePO4 I purchased was only $16 for example, so if I happen not to get the ultimate number of potential cycles out of it because I let it charge to 100% I'm OK with that.

BTW, today I was testing the TQKA and running two Mobius cameras it dropped to 10% from fully charged in about an hours time. As I was out of state and about 50 miles from home I just let it run all afternoon and into the evening and then when I got home it was still showing 10% and plenty of juice left in it. So, it seems the percent-of-charge display has a problem but the battery cells and charge circuitry seems fine. At the same time I was also running two other dash cams on my other TQKA LiFePO4 Pentagon. That one started out the day at 100% charge and ended up at 83% when I arrived home.
 
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Reeflekt

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With in 2 hours of use the charge dropped 5 levels from 89% to 84% the outside temperature was 95F, I'm not sure how hot was in the car. The power bank wasn't warmer than any other interior parts of the car.

After getting home I switched the cam to the power bank the outside temp dropped to 70F the percentage after 3 hours of use is now 78%. It produces absolutely no heat. The power bank is connected to the A119 no GPS. The cam is in parking mode 5 fps all the time.

I'll try to follow advise discharge and charge procedure in order to make it last and serve longer.
 

Dashmellow

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Power banks should never produce any heat. If they do there's a problem. I'm referring to the battery cells, not the electronics. One power bank I owned did get pretty warm on one end where the circuitry was located if it ran for a long period of time. The TQKA does seem to remain pretty cool to the touch even in a warm car. I think it has to do with the thick aluminum housing.
 

EsQueue

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@Dashmellow Yeah, I fully charge and discharge my cells to 3.0. I figure that I'll just replace them when they get worthless. I love the LiFePO4 for automotive applications and when I build something for my mother. I find that I am way more careful and test multiple times and add more fuses to power banks that I build for my mother. My dumbass built a 13s10p battery for my bike and it isn't even fused. It does have a 10S and 3s BMS in parallel though. I also like to have balance cables on all my batteries so if I decide to charge via hobby charger.
 

Reeflekt

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Today I observed interesting phenomenon. The power bank was showing 38% of charge (if it was accurate) and after only 2 hours it was dead. The cam wasn't getting any juice. Now it's charging through the PC's usb cable, but this drastic drop was unexpected.
 

Dashmellow

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Well, today I decided to see what would happen if I continued to use the TQKA that dropped to 10% after slightly more than an hour's usage running my two Mobius side cams yesterday yet continued to perform well during my 50 mile journey home from out of state.

So, I started out today with the power bank uncharged from yesterday and still showing a 10% charge on the "fuel gauge". It powered my cameras for about three and a half hours with no issues and when I arrived back home it was still registering 10%. I have a hunch it would have run all day like that and I believe it is accepting and holding a full charge despite what the read-out states. At some point I'll do a full discharge test with my USB voltage/current tester which has a 99.99 hour timer function.

If I charge the unit the gauge will slowly go back to 100% as one might expect and then it will fall precipitously under load when I go to use it again. Then it continue to maintain a strong, long lasting state of charge. This has been quite repeatable.

It seems the problem with this unit is indeed with the circuitry that measures and displays the amount of current but the battery cells and charging circuitry seem fine.

Interestingly, the other unit, the one that spent a couple of months stuck at 96% is working fine. Yesterday, it started out at 100% and by the time I got home it was registering 87%. Today it dropped from 87% to 79% during the three and half hours of use.

@Reeflekt, when you say your unit was "dead", do you mean it has no charge left at all or do you mean the gauge was at 0% after two hours but it still had some juice. I'm wondering if perhaps they sold you a unit someone else returned. It may explain why they suddenly had a single unit in stock.
 

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It was totally dead. The PB wasn't displaying any numbers and the cam was off. I tried to charge other devices, but they weren't charging.

I was also thinking that the PB is refurbished, but I couldn't find any signs of use, micro scratches or the finger prints even the pouch was brand new. If in fact it was customer's return they did a great job to refurbish it to a brand new condition.
 

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@Dashmellow I believe that it is difficult to get a proper charge reading on LiFePO4 using the cheap voltage gauge that many powerbanks use. A self configuring gauge that measures and stores the data on the amount of outgoing current is the only way to get a really good reading and you are not going to find that on most powerbanks.

The reason is that LiFePO4 usually quickly settles to something near 3.2 volts depending on the current draw and will stay there for almost 90% of its life. Google a LiFePO4 drain chart and you will see what I am talking about. I wouldn't doubt that you will get years of life on your existing packs due to the reliability of LiFePO4. It is usually the circuitry that fails on many packs. A BMS failure will render any battery pack dead.
 

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Today I observed interesting phenomenon. The power bank was showing 38% of charge (if it was accurate) and after only 2 hours it was dead. The cam wasn't getting any juice. Now it's charging through the PC's usb cable, but this drastic drop was unexpected.
Are you sure that your device is using the full power available via PD? I've only recently discovered PD when I was making a project that required it. I know that QC used the data pins to either send a resistance or communicate and allow the charger to change to a higher current. Do you have some kind of high voltage trigger? I can only get max 500ma from my QC 3.0 chargers when using a 2 pin usb cable. .
 

Dashmellow

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@Dashmellow I believe that it is difficult to get a proper charge reading on LiFePO4 using the cheap voltage gauge that many powerbanks use. A self configuring gauge that measures and stores the data on the amount of outgoing current is the only way to get a really good reading and you are not going to find that on most powerbanks.

The reason is that LiFePO4 usually quickly settles to something near 3.2 volts depending on the current draw and will stay there for almost 90% of its life. Google a LiFePO4 drain chart and you will see what I am talking about. I wouldn't doubt that you will get years of life on your existing packs due to the reliability of LiFePO4. It is usually the circuitry that fails on many packs. A BMS failure will render any battery pack dead.
I agree that the voltage gauges in many power banks are likely not all that accurate but when you have a 20,000 mAh battery bank that drops from 100% to 10% after an hour or so under modest load it clearly has a defect. Other power banks I've owned that have a digital read-out seem to work reasonably well. With the experience from my TQKA banks so far though I think I'd probably have been happier with a simple four LED power indicator that provides an approximate percentage of the charge state assuming it would work the way it is supposed to.

You're right about LiFePO4 discharge. They have a long stable plateau before dropping off compared to li-ion. I do wonder about some of the charts we see online though as they are based on bench tests in stable controlled conditions using very specific C rates. I have a hunch discharge conditions and temperatures out in the field, especially running dash cams in an automobile might yield different looking charts. I imagine the basic characteristics of different battery chemistries would remain more or less consistent though. Anyway, I also think you're right that the four big LiFePO4 cells inside the TQKA should last a very long time. I understand that they are often used in remotely deployed solar charged scientific instruments for this reason - along with the stable discharge characteristics and heat tolerance.
 

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When you have a 20,000 mAh battery bank that drops from 100% to 10% after an hour or so under modest load it clearly has a defect.
You got a point. :LOL:
It was totally dead. The PB wasn't displaying any numbers and the cam was off. I tried to charge other devices, but they weren't charging.

I was also thinking that the PB is refurbished, but I couldn't find any signs of use, micro scratches or the finger prints even the pouch was brand new. If in fact it was customer's return they did a great job to refurbish it to a brand new condition.
I suspect that the charge displayed was incorrect and after using it, the voltage got low enough that the BMS cut power. How is it working after a full charge? I expect it to work after.
 

Dashmellow

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You got a point. :LOL:

I suspect that the charge displayed was incorrect and after using it, the voltage got low enough that the BMS cut power. How is it working after a full charge? I expect it to work after.
The thing seems to work fine. It apparently takes a full charge and holds it. So far, it just seems that the display is all screwy. Like I mentioned last night I plan to do a full drain test at some point when I have the time.
In the meantime I charged it this morning and will be using it in my truck for a few hours when I head off to town like I did yesterday. I notice it doesn't take very long to charge right back up to 100% (about 90 minutes) which seems to indicate that there's plenty of juice still in the cells even after running at 10% all afternoon yesterday.
 

Reeflekt

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After the first recharge this thing is indeed building a stamina. I left it running overnight (ambient temp 55F) it dropped only 10% within 9 hours.
I dont believe of consistency of the numbers displayed on the gauge I'll keep monitoring and comparing the numbers to the actual working time.
 
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