Official Owners Thread : TQKA 20,000 mAh LiFePO4 Battery

SawMaster

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G1W-S, G1W-HC, G1W clone, B1W, K2S, B2W, (ex N2Pro & Mobius)
May be out-of-stock due to Chinese New Year holiday?

Phil
 
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Submariner Gold

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Just discovered a bonus feature with the TQKA .
By connecting a USB Meter, I have discovered that, once the TQKA is fully charged, it stops charging; well the meter says it drops to 0 Amps input and stays stone cold.
( tested it about 6 times ).
A benefit for me; as I can plug it into the boot cigar lighter charger port on a long jpurney, knowing it will be fully charged should I need to run the dashcam overnight - in say a Hotel Car park.
There is even a net pouch and strong velcro securing strap ( originally for a first aid kit .... like you would ever need that with an S Class Coupe. If you are damaged in this tank .. its an air ambulance job lol :):) ) to hold the battery securely right underneath it.

So well pleased :)
 
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Dashmellow

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All power banks terminate charging once they are fully charged.

Lithium-ion batteries become unstable and can experience a thermal runway if charged to more than 4.3 volts so all chargers will terminate the charge at 4.2 volts. Although LiFePO is more tolerant to overcharge than cobalt type Li-ion, it's still not good for the battery to overcharge or float charge. Lithium batteries should also not be permitted to drop too low in voltage either and so all power banks have a low voltage cut-off circuit which engages when discharge reaches 3 volts. (as do a all laptops, phones and other mobile devices) Many standard lithium-ion cells have a protection circuit built in that will open if the cell discharges below approximately 2.5 which will then render the battery permanently unserviceable with a regular charger.
 
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Submariner Gold

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So its the charger that stops charging not the battery pack that that shuts down?
I am a bit confused
When You say ... “become unstable and can experience a thermal runway if charged to more than 4.3 volts”
My USB meter says its charging AT 4.96V, when its being charged by a 2.1A 5 V Apple iPad Air charger.

I assume your 4.3V is not that ? .... but more like the voltage of a 12V AGM battery, where the full charge is 2.1V per cell, with 6 Cells delivering 12.6V as fully charged. Is that what you meant ?

I ordered from Amazon this Aukey USB Car charger to insert in my boot 12V Cigar lighter socket.
https://www.amazon.co.uk/gp/B06XFMFGY4
Will that know my power pack is lithium ion based and shut off accordingly?
 

Dashmellow

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The power bank consists of battery cells and built in charging circuitry that monitors the cells and controls the charge and discharge. That built-in circuitry will terminate the charge when it is full (or shut down the power bank when the cell voltage drops too low) regardless of whether it is still receiving voltage from an external source.

The Aukey or Apple charger is merely providing voltage and current to the power bank, it is not controlling the power bank. Some USB chargers do have some "smart functions" and the Aukey in your link claims to prevent overcharging but the TQKA wouldn't be aware of that and is designed to make its own determination as to whether it is fully charged.

The charger is merely supplying the current and voltage it is rated to output. Just because the Apple charger is supplying 4.96 volts when connected to your TQKA doesn't mean that the power bank will charge its internal cells beyond their rated upper limit of 4.2V. The power bank's internal battery charging circuitry will manage the incoming voltage and current. This is the same thing that is happening when you charge your iPad Air with this charger. It is circuitry inside the iPad Air that is controlling the charge to its own internal battery just the same as the TQKA is controlling the charge to its internal cells.
 
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Submariner Gold

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The power bank consists of battery cells and built in charging circuitry that monitors the cells and controls the charge and discharge. That built-in circuitry will terminate the charge when it is full (or shut down the power bank when the cell voltage drops too low) regardless of whether it is still receiving voltage from an external source.

The Aukey or Apple charger is merely providing voltage and current to the power bank, it is not controlling the power bank. Some USB chargers do have some "smart functions" and the Aukey in your link claims to prevent overcharging but the TQKA wouldn't be aware of that and is designed to make its own determination as to whether it is fully charged.

The charger is merely supplying the current and voltage it is rated to output. Just because the Apple charger is supplying 4.96 volts when connected to your TQKA doesn't mean that the power bank will charge its internal cells beyond their rated upper limit of 4.2V. The power bank's internal battery charging circuitry will manage the incoming voltage and current. This is the same thing that is happening when you charge your iPad Air with this charger. It is circuitry inside the iPad Air that is controlling the charge to its own internal battery just the same as the TQKA is controlling the charge to its internal cells.
Thanks so much for your valuable time to explain in detail.
Very Much appreciated.
Always good to learn new stuff even at my age :)
 

Rajagra

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I didn't get a mesh bag or velcro strap with mine. Just a fabric bag that doubles as a lens/screen cleaner. Maybe I should double check the box.

Re: charging, I have a USB tester with a useful feature. It lets you set a timer so it shuts off power after a while. Alternatively if can shut off when power drops below a certain level (2W if I recall right.)
Either option could further protect against overcharging. Although not strictly necessary, it can be healthy to avoid charging to 100% unless you really need it.

https://www.amazon.co.uk/gp/B071L1LTVV
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Dashmellow

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I have some bad news to report about my TQKA power bank.

After purchasing the TQKA this winter and testing it out thoroughly I decided to put it away until the warmer weather arrived before using it in my vehicle. For the time being, my standard lithium-ion battery backs seemed just fine operating for long periods in my vehicle here in New England when the winter temperatures were still quite cold. Not that I've had a problem during hot summer months using lithium-cobalt power banks mind you, but LiFePO and lithium-polymer (as opposed to 18650 celled power banks) seem a good hot weather alternative.

The standard recommendation for long term storage of lithium batteries is to keep them at about 50% charge, so that's how I always keep power banks that are not in daily use.

So, I had two 20,000 mAh power banks that I put in storage at the same time until they were needed, both charged to 50%. One is a PowerAdd Power Pilot which is essentially a single huge lithium-polymer cell. (also safer for warmer operating conditions) The other, of course, is the TQKA LiFePO. When I recently went to check on these banks that I last used in early March, the PowerAdd was still at 50% charge and the TQKA was stone cold dead......0%!

I gave the TQKA an overnight charge and it's back to 100% and seems fine (for the time being) but the fact that it lost all of its juice is worrisome and certainly not a good sign.

I need to do a bit of research and find out more about long term storage of LiFePO batteries.
 
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Rajagra

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I still haven't used mine much but think I used it to charge a phone 2 weeks ago. It is currently reading 78%. But I don't think it works this out from the cell voltage. It seems to track how much power has gone out through the ports, deduct this from the theoretical capacity, and calculate what SHOULD be left.

There are two flaws with that. The cells may not have the capacity they are supposed to (especially when old.) And it doesn't take account of self discharge. So when it gets low it can jump from, say, 20% to 0% really quickly.

And trying to store it at 50% charge would be risky if the reading is inaccurate.

I'll do another discharge test without recharging first.

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Submariner Gold

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I have some bad news to report about my TQKA power bank.

After purchasing the TQKA this winter and testing it out thoroughly I decided to put it away until the warmer weather arrived before using it in my vehicle. For the time being, my standard lithium-ion battery backs seemed just fine operating for long periods in my vehicle here in New England when the winter temperatures were still quite cold. Not that I've had a problem during hot summer months using lithium-cobalt power banks mind you, but LiFePO and lithium-polymer (as opposed to 18650 celled power banks) seem a good hot weather alternative.

The standard recommendation for long term storage of lithium batteries is to keep them at about 50% charge, so that's how I always keep power banks that are not in daily use.

So, I had two 20,000 mAh power banks that I put in storage at the same time until they were needed, both charged to 50%. One is a PowerAdd Power Pilot which is essentially a single huge lithium-polymer cell. (also safer for warmer operating conditions) The other, of course, is the TQKA LiFePO. When I recently went to check on these banks that I last used in early March, the PowerAdd was still at 50% charge and the TQKA was stone cold dead......0%!

I gave the TQKA an overnight charge and it's back to 100% and seems fine (for the time being) but the fact that it lost all of its juice is worrisome and certainly not a good sign.

I need to do a bit of research and find out more about long term storage of LiFePO batteries.
If this helps.
I only connect mine if I am going somewhere rough. Hence my TQKA was last used in early Feb. Circa > 3months.
It was left at 100%. Just checked it now and it states 100%. :):)
So one cant really ask for more. I am very pleased with it.

Another poster claims this reading is not based on Voltage but a deduction of power used.
I dont know how he found this out ... as TQKA are nigh impossible to contact.
 

Rajagra

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The reason I think that, is through using a USB tester and load resistor to discharge it. The power reading dropped precisely as it would if the actual capacity was exactly the claimed capacity. It did this all the way down, there was no random discrepancy you would expect with a real world battery.

Until the point it suddenly died before it should have.

The figures did not match the actual capacity of around 50Wh. Only the claimed capacity - 64Wh.

I'm repeating the test now, I'll try to check the readings every hour.

I don't mean to trash the Tqka, I've since bought another of their power banks that matches the size of my phone.

Sent from my SM-G903F using Tapatalk

 
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Dashmellow

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I still haven't used mine much but think I used it to charge a phone 2 weeks ago. It is currently reading 78%. But I don't think it works this out from the cell voltage. It seems to track how much power has gone out through the ports, deduct this from the theoretical capacity, and calculate what SHOULD be left.

There are two flaws with that. The cells may not have the capacity they are supposed to (especially when old.) And it doesn't take account of self discharge. So when it gets low it can jump from, say, 20% to 0% really quickly.

And trying to store it at 50% charge would be risky if the reading is inaccurate.

I'll do another discharge test without recharging first.

Sent from my SM-G903F using Tapatalk

Power banks have circuitry that measures SoC (state-of-charge) internally, not by how much power has "gone through the ports". As far as I understand the circuitry internally monitors both current AND voltage.

You are correct about self discharge but it happens quite slowly (or should at least).

Isador Buchmman, the battery engineer behind Battery University recommends approximately 40% charge for long term storage. ("Finding the exact 40–50 percent SoC level to store Li-ion is not all that important.")

"Lithium-based chemistries should be stored at around a 40 percent state-of-charge (SoC). This minimizes age-related capacity loss while keeping the battery operational and allowing for some self-discharge."

He shows that lithium batteries at 40% charge should hold for about one year or longer despite self-discharge AND capacity loss. LiFePO chemistry should conceivable last longer and is why it is used in many remote solar powered applications and monitoring devices.

storage-li_ion.jpg


Numerous authoritative sources advise putting lithium based batteries in long term storage at 30-50% state of charge.

http://batteryuniversity.com/index.php/learn/article/how_to_store_batteries

http://www.mpoweruk.com/storage.htm

http://www.newark.com/pdfs/techarticles/tektronix/LIBMG.pdf


MY TQKA should NOT have lost ALL of its capacity after only two months storage at 50% charge (at slightly below average room temperature.)
At the moment it has been holding 100% charge for the last two days. I plan to leave it alone and keep my eye on it.
It's possible the unit I received has one or more bad cells.
 

Rajagra

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Power banks have circuitry that measures SoC (state-of-charge) internally, not by how much power has "gone through the ports".
That is my point. The former is what you need and expect, but my tests do not match that.

E. G. So far today my Tqka has gone down by about 10% according to the display, and pumped out about 6.4Wh according to my USB tester. That's 10% of the claimed 64Wh capacity. Perfect! Too perfect, though. I know it only gives out about 50Wh. We'll see what happens next.

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Dashmellow

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That is my point. The former is what you need and expect, but my tests do not match that.

E. G. So far today my Tqka has gone down by about 10% according to the display, and pumped out about 6.4Wh according to my USB tester. That's 10% of the claimed 64Wh capacity. Perfect! Too perfect, though. I know it only gives out about 50Wh. We'll see what happens next.

Sent from my SM-G903F using Tapatalk
So far in actual use, my TQKA has performed admirably. The question of why it lost all of it's charge during two months of storage at 50% seems to be a different question. For now, I'm just going to let it sit without being used and see what it does. Time will tell.
 

Rajagra

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Maybe I'm wrong about it assuming the full 64Wh capacity, it now seems to have calibrated, and expects around 52Wh.

However it still gets it wrong at the end and dies suddenly. The first 17% drop took over an hour. The final 17% only lasted 17 minutes, at a pretty constant 2A load.

If the 78% status at the start was accurate, it would mean a 45.7Wh capacity.

I still suspect it is discharging when idle and the remaining % display does not track this.

It does still power up to show 0%.



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Submariner Gold

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I am very pleased it made 3 months still at 100% .
Interesting facts, but as it only cost £20 delivered.
It is what it is.
If it degraded a lot in the future ... luckly where it is stored in the boot, is right by another charger port.
So on the way to my destination, I can leave it charging :)
 

Rajagra

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Interesting facts, but as it only cost £20 delivered.
It is what it is.
LOL, true. As a fairly high capacity, safer type of power bank good for use in the motor, it's a steal.

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My first 20,000mAh power bank (li-ion) was purchased on Amazon for $22.00 USD in March 2014 and has been in near daily extended use since then in all kinds of temperature extremes. It's also endured quite a lot of shock and vibration driving around on bumpy rural dirt roads. Only recently has it started showing it's age in reduced capacity and long charge times but from all appearances has quite a lot of life left in it.
 

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does this powerbank support pass through charging?
 
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