Does anybody know of any powerbanks with pass-through charging?
The TP5100 chip used in the BLF LT1 lantern for charging can input/output at the same time. In fact, the lantern will be able to work without batteries if a power supply is plugged into the USB charging port.
Here is a simple charging board available on eBay which uses the TP5100 chip.
I think the gen2 xiaomi 20,000mAh have 5V pass through but not sure if there is a switching
when input power is disconnected. Most UPS doesn’t have switching but DIY solar controller + 12V battery charger 2in1 does. I can check it out and let you know which powerbank in my collection have non-switching pass through (always on or separated buck-boost controller).
@ Will34,
Thanks, would appreciate that!
Awesome find!
There are some more UPS especially for small electronics:
ebay.com/itm/Mini-UPS-Uninterruptable-Power-Supply-System-with-POE-Current-Transfer-Function/183952535867
ebay.com/itm/Mini-UPS-Uninterrupted-Power-Supply-7800mah-12V-2A-USB-5V-1A-Output-GM312/383191878917
ebay.com/itm/1575192-Vultech-UPS30PW-DC-Bianco-Mini-UPS-30-Watt-Gruppo-di-Continuita-Portatil/401874780975
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It would work, but it’s not available anymore: “Currently unavailable”
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They sell it in germany:
ebay.com/itm/12V-USV-Mini-USV-unterbrechungsfreie-DC-Stromversorgung-12-V-22-W-2000-mAh/122971057294
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Sure:
Blitzwolf QC3 power bank 10000mAh BW-P3, fixed version
Blitzwolf QC3 power bank 15600mAh BW-P5
Miller ML202 V4
Ravpower Turbo+ RP-PB043 (20100mAh)
Soshine E4S
Thrunite C2 power bank and charger
Tomo Power bank M2
Tomo Power bank M4
Thanks angerdan
The Ravpower looks good on review
I can’t find it for sale though.
Here it is:
amazon.de/RAVPower-20100-mAh-tragbares-Ladegerät-Technologie-schwarz/dp/B019IH53MA
amazon.de/RAVPower-20100mAh-Powerbank-Anschluss-Kapazität-schwarz/dp/B019GI39VI
heise.de/preisvergleich/eu/ravpower-xtreme-20100mah-rp-pb043-a1449786.html
My blackweb 20k mah powerbank with type c powerdelivery does passthrough
I have tested these DIY powerbanks below if they can be UPS for RPi, Routers, etc.
1. Tomo PowerBank S4 (4x 18650; Similar to M4/M2; 5V/1A input) - Can do pass-through charging but does not seem to be able to charge the battery while using the output, this maybe due to input power limited to 1A. Unplugging the input power does not cause a surge on the output USB.
2. Soshine E3S-QC (4x 18650; QC 3.0 on USB Out 2) - Can do pass-through charging, but unplugging output causes a less than a second power surge before switching to battery. While pass through charging, the USB output port 1 (5V/1A) is turned off.
3. Epilot E4 (4x 18650; 5V 2A input) - Similar to Soshine E3S-QC, but can still provide power to both USB outputs on pass-through charging.
In my case, I am trying to power an Intel Compute Stick for hotspot router. Will try this one RPi UPS with DIY battery: 52Pi Original 18650 UPS Pro Power Supply Device Extended Two USBA Port for Raspberry Pi 4 B / 3B+ /3B
The following stuff is advertised as UPS, besides being a DIY power bank meant to provide power for up to 65 W laptops:
https://www.aliexpress.com/item/4000268838287.html
Battery arrangement is 3S2P, but if I were to buy one I'd make windows on the cover and install more batteries (of course all soldered or spot welded).
There are some related videos out there. 
thanks
Some are said to work starting cars. True?
Some car starters offer 200-400A.
https://enerprof.de/en/portable-energy/powerbanks/28/tensai-tb-13600-car-jump-starter/power-bank
Do you have any links to those videos please?
Lots of possibilities out there, important question.
e.g. https://www.instructables.com/id/DIY-Mini-UPS-for-Router-Modem/
I’d like to see a reliable answer.
Nitecore F1
Search for yourselves fellows, it is wise to do so.
In any case, as guiding beacon here's a simplified search link for AILI UPS laptop power bank on Google, videos category: https://www.google.com/search?q=AILI+UPS+laptop+power+bank&source=lnms&tbm=vid
For reference I'd choose this fellow which at least isn't using recycled laptop batteries:
It of course is better to spot weld or solder the batteries, battery contacts can cause some meaningful voltage drop at high loads and this device can drain up to 8 A from the batteries (4 A per cell).
I've been tempted to buy it sometime, but really have no need for it right now and anyway I'd prefer for it to be professionally reviewed (HKJ).
I sometimes send stuff to be reviewed to HKJ, but I'm tight on money. If someone is interested he/she can either send the device to Henrik, or make me a donation of at least ⅔ the cost for it to be shipped to Denmark. In this case (shipped to Denmark) this other seller has it slightly cheaper at ≈€12.22-12.33 total with tracked shipping: https://www.aliexpress.com/item/32990184912.html
If someone wants this to be done, I'll make Henrik confirm the item is on the way to his lab here: Review request for HKJ [USB Power Devices]
In order to increase the lifespan of the battery most UPSes are line interactive, so they just pass power through them without having the battery connected.
When it detects power loss it connects the battery in a few milliseconds.
You can’t use a power bank to do something like this, they have no method of disconnecting their battery.
Good point, certainly. If I were to need the stuff for such role I would find a way to limit charge voltage. Even if no way to adjust it in the circuitry, installing some in series diode(s) to limit the charge voltage is an option, but it would also require employing some high amps ideal diode to allow current from the battery to flow unimpeded the other way around. See: