Update: This popular deal is still available.
Lenovo Product Marketplace, Inc. via Amazon has
TALIX 20000mAh 3-Port 140W USB-C Power Bank on sale for $69.99 - $31 when you apply promo code
ET38K7BB at checkout =
$38.99.
Shipping is free.
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Thanks to Community Member
online4fun for sharing this deal.
Details:
- 140W PD 3.1 single-port super charging (USB-C1) for high-power laptops (requires PD 3.1 EPR cable and compatible device)
- 20,000mAh high-capacity battery: ~3.8 full charges for iPhone 16 Pro Max or ~1.2 full charges for MacBook Air M3
- 100W dual-port self-charging: fully recharges in 75-80 minutes
- Airline-approved (73Wh) and travel-safe: compact size (6.06 x 2.0 x 1.53 in) and lightweight (14.8 oz)
- Charges 3 devices simultaneously: 2 USB-C + 1 USB-A ports (max single-port 140W)
- Smart digital display: shows battery percentage, remaining time, temperature, and real-time power/voltage per port
- Digital Hybrid Charging: can charge while powering devices, combining internal battery with external adapter for up to 140W output
Top Comments
Community Reviews
This TALIX 140W USB C power bank stands out as a slim 20,000mAh laptop charger with strong fast charging and useful hybrid pass through behavior. It has powered laptops, handheld PCs, and even acted like a UPS for a small USB load, while staying cool and looking well built. The deal price also lands well below similar UGreen and Anker units, and the coupon has repeatedly worked. Main caveats are uneven laptop compatibility, especially with some Dell and Framework models, plus reports of screen failures, touch sensitive buttons, and lower than expected real world capacity from the built in efficiency loss.
The coupon code ET38K7BB and the clipped listing coupon can reduce the total price successfully.
The unit can stay relatively cool during fast charging while delivering laptop charging on road trips.
The power bank can act like a UPS for a low-power USB device during unplug and replug events.
Amazon support can provide a replacement when charging issues occur with the power bank.
The power bank can fail to negotiate and supply power to some laptops, including Framework 16 and certain Dell models.
The listing indicates built-in inefficiencies that can reduce delivered capacity to about 11,700mAh from a 20,000mAh cell.
The screen can die after about two weeks even while the power bank continues working.
The power bank can be too thick for an everyday bag despite working well otherwise.
Common Questions (5)
AI-generated summary based on comments from the community. Updated ago
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59 Comments
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I think this is a translation mistake. The cells are 4.2V and 20AH. At 8.4V you'll only get 10AH and at 12.6V output you'll only get 6.67AH, all at 100% efficiency. You have to do the math in watts - AH doesn't work if the voltage in (battery) and voltage out (to laptop, phone ,etc) is not the same.
In any case these are certainly 95% efficient ish. Otherwise they would get very very hot when outputting 100w
That being said i should have the equipment at home to test and measure when it comes in on Friday.
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That being said i should have the equipment at home to test and measure when it comes in on Friday.
DC/DC conversions can be in the mid to upper 90's as you say. It can also be a good bit lower. Generally, the larger the ratio between input and output voltage is, the less efficient a DC/DC is. Supposedly most power banks put the batteries in parallel, not series, which increases the DC/DC ratio when working with higher PD voltages and thereby decreasing DC/DC efficiency.
Battery efficiency is variable based on charge/discharge rate. I see numbers for batteries between 85-95%. Makers of these USB power banks are emphasizing power density for minimum size and weight which tends toward batteries that are less efficient. The power banks are also pushing charging fast and having high power output. That uses the the batteries at a lower efficiency point.
If all 3 factors are 90% you end up with a total system efficiency of 72.9%. None of the individual steps seem that bad by itself, but after stacking the three the total system efficiency looks poor.
I'm working through testing many of my USB power banks putting a 75% wattage load (of the max single USB-C capability) at the highest supported PD voltage on them via USB-C PD and then letting them recharge however fast they want from a 100W USB-C PD charger and so far the most efficient one is 77.5%. The worst so far is 72.5%. I found a 45W Ugreen that consistently overheats and turns off it's output with a 75% load (33.7W) whether outputting 12V, 15V, or 20V.
Discharging a power bank slowly at 5V and charging slowly at 5V would likely improve the measured efficiency, but that's generally not how they're used.
DC/DC conversions can be in the mid to upper 90's as you say. It can also be a good bit lower. Generally, the larger the ratio between input and output voltage is, the less efficient a DC/DC is. Supposedly most power banks put the batteries in parallel, not series, which increases the DC/DC ratio when working with higher PD voltages and thereby decreasing DC/DC efficiency.
Battery efficiency is variable based on charge/discharge rate. I see numbers for batteries between 85-95%. Makers of these USB power banks are emphasizing power density for minimum size and weight which tends toward batteries that are less efficient. The power banks are also pushing charging fast and having high power output. That uses the the batteries at a lower efficiency point.
If all 3 factors are 90% you end up with a total system efficiency of 72.9%. None of the individual steps seem that bad by itself, but after stacking the three the total system efficiency looks poor.
I'm working through testing many of my USB power banks putting a 75% wattage load (of the max single USB-C capability) at the highest supported PD voltage on them via USB-C PD and then letting them recharge however fast they want from a 100W USB-C PD charger and so far the most efficient one is 77.5%. The worst so far is 72.5%. I found a 45W Ugreen that consistently overheats and turns off it's output with a 75% load (33.7W) whether outputting 12V, 15V, or 20V.
Discharging a power bank slowly at 5V and charging slowly at 5V would likely improve the measured efficiency, but that's generally not how they're used.
A couple of things to note, what you call "battery efficiency" is more commonly described as faradiac efficiency (or sometimes called coloumbic efficiency) does not vary significantly with lithium ion chemistries. It had more of an impact especially lead based chemistries and sometimes Nickel based but lithium based is typically 99% as long as you're within 1-4C rates (although at higher C's you'll experience more IR losses). Aso this applies during charging and discharging.
Modern DC/DC converters are typically between 92-98% depending on load as well with the peak efficiencies typically between 30-60% load and it dropping off as you reach max ratings and minimum ratings. But you can typically use 95% for most intents and purposes. Assuming you're charging a device at 60W (out of this units 140w limit) which falls well within optimal conditions, you could.
What this means there are 4 conversion steps if you're looking at roundtrip energy efficiency, and 2 steps if you're only caring about output capacity (ignoring the conversions needed on the device itself).
ȠB = faradiac effiency (this does not vary signfiicantly with lithium chemistries)
ȠDC-DCi = DC Input Efficiency (this varies based on input power, but has a fixed maximum input)
ȠDC-DCo = DC Onput Efficiency (this varies based on output power, but has a fixed maximum output)
A roundtrip efficiency can be described as (which is 4 steps):
ȠDCi-DCo = (ȠB * ȠDC-DCi) * (ȠDC-DCo * ȠB)
But the above value isn't particularly interesting since DC input to DC output is usally from a grid source rather than another DC source. So all you usually measure is the DC output efficiency which is only 2 steps (not the 3 you described).
ȠDCo = (ȠDC-DCo * ȠB)
So all you should really care about is the DC output efficiency + fardaic efficiency to simplify characterization of the battery bank. Consider that these devices output at 5, 9, 12, 15, 20, and 28 volts at up to 5 A, it would be quite a bit of work to do so for each product.
Tried my Dell Latitude Precision again, and it still fails to charge as tries to negotiate to 20v but fails. My Baseus has no problem charging the Dell at 28v at 5 A. Further testing needed.
Modern DC/DC converters are typically between 92-98% depending on load as well with the peak efficiencies typically between 30-60% load and it dropping off as you reach max ratings and minimum ratings. But you can typically use 95% for most intents and purposes. Assuming you're charging a device at 60W (out of this units 140w limit) which falls well within optimal conditions, you could.
What this means there are 4 conversion steps if you're looking at roundtrip energy efficiency, and 2 steps if you're only caring about output capacity (ignoring the conversions needed on the device itself).
ȠB = faradiac effiency (this does not vary signfiicantly with lithium chemistries)
ȠDC-DCi = DC Input Efficiency (this varies based on input power, but has a fixed maximum input)
ȠDC-DCo = DC Onput Efficiency (this varies based on output power, but has a fixed maximum output)
A roundtrip efficiency can be described as (which is 4 steps):
ȠDCi-DCo = (ȠB * ȠDC-DCi) * (ȠDC-DCo * ȠB)
But the above value isn't particularly interesting since DC input to DC output is usally from a grid source rather than another DC source. So all you usually measure is the DC output efficiency which is only 2 steps (not the 3 you described).
ȠDCo = (ȠDC-DCo * ȠB)
So all you should really care about is the DC output efficiency + fardaic efficiency to simplify characterization of the battery bank. Consider that these devices output at 5, 9, 12, 15, 20, and 28 volts at up to 5 A, it would be quite a bit of work to do so for each product.
Since the power bank has an unknown amount of usable battery capacity it's impossible to determine the output efficiency by itself (without disassembly). You can measure the round trip efficiency and divide by two, but you can't directly measure just the output efficiency (without disassembly).
I await for your data showing that this is 90+% efficient.
Since the power bank has an unknown amount of usable battery capacity it's impossible to determine the output efficiency by itself (without disassembly). You can measure the round trip efficiency and divide by two, but you can't directly measure just the output efficiency (without disassembly).
I await for your data showing that this is 90+% efficient.
After that weridness that, I did plug it in, and it did get about 80 Wh out of the 74 Wh rated so charging efficiency of about 91.65%. My first test was limited since I didn't have a good load ready yet, and it various loads I had around the house kept getting plugged in/unplugged but I used it with 5v, 9, 12, 15, 20v loads. Total output was measured at 64.98 Wh (64.98 / 74 = 87.8% efficient) but keep in mind this was discharged over 5 hours, and there was a load from the screen + my measurement tool so if tat was ~0.5 w draw for the two screens/electronics 5 * 0.5 = 2.5 wH, brings the net efficiency to about 91.18% efficient on the discharge across the voltage ranges.
Unfortunately my time was limited so I wasn't able to do a proper test again before the battery decided to fail and capacity dropped from 80-82 Wh charging input to only 68 Wh input. Looks like the battery went kaput because something broke, since I was only getting about 59 Wh output after that, but it was getting 69 Wh input (Charge / Discharge cycle 4), so roundtrip efficiency there 84% so about 92% efficient each direction. I took pictures of each cycle but a bit lazy to post it all so I'll just post the table, as well as the video of the really awkward behavior of that first discharge cycle.
Table of charge/discharge data.
https://imgur.com/sgeOXdp
Also here's the video of that super weird initial behavior as well as pictures of all the charge/discharges.
https://www.dropbox.com/scl/fo/6r...ujh9f&dl=0
Also did you find it interesting that I was about get more energy in when it was charging at the faster rate?? A less well known fact about batteries is that the hotter they are, the more power/energy they can hold. That is why Tesla actually "pre-conditions" their cars to about 45 C / 113 F before you hit a supercharger to speed up charging and charge acceptance.
Thanks for the effort though.
Thanks for the effort though.
One nice thing to report given my issue Talix decided to refund me so the unit was free. I can do another run at 90w charging to see how the capacity compares at lower charging rates (15w). I suspect the efficiency is lower on the lower charging rate since the Screen itself stays on longer so you get more parasitic losses.
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