# USB powerbank WITHOUT auto off?



## subwoofer

I'm hoping the collective can point me in the direction of a USB powerbank which can be permanently turned ON. I have a USB powered clock which on the lowest brightness setting draws so little power, every single USB powerbank I own, automatically shuts off. I have to set it to the highest output for the current draw to be sufficient to keep the powerbank operating.

What I'm looking for is a powerbank that will keep the USB output live regardless of the current draw (like a mains charger would). I realise this means the calls will run down even with no USB load, but need to be able to decide myself when the USB socket is live.

I'd like it to be a reasonable brand (not a no-name hope-for-the-best type product) if possible.

Any ideas?


----------



## Julian Holtz

I own this power bank:
https://www.fasttech.com/products/0/10004461/1341206-qidian-1a-1-5a-2a-4a-6-18650-mobile-power-bank
http://budgetlightforum.com/node/25609
The version without cells and accessories is way cheaper, but discontinued. It has a switch to deactivate the auto-power-off.


----------



## Phlogiston

Not an ideal solution, because it requires some tweaking and wastes some power, but it is possible to build a dummy load that draws enough current to keep a power bank on: 

http://www.dorkbotpdx.org/blog/paul/battery_pack_load


----------



## Lynx_Arc

I've had the same issue in that I have these LED USB plug in boards that have a dimming circuit such that you can dim them down to very low current levels of which most power banks shut off. I've gone through a bunch of power banks and have found only a few that can manage to stay on. The following are the ones that will stay on at current levels of 1ma (or less).

1) Pocket Juice single cell power banks (Walmart) in black and neon pink
2) Ebay lipstick power banks metal cases you screw the bottom cap off to insert an 18650
3) Ebay plastic round power banks that are 2 piece white and a color
4) Ebay plastic square 2 cell power banks colors with white covers 

Warning... I have found that circuit designs of power banks change often. I've found the square Ebay power banks (4) have mostly gone to circuits that don't support low current levels. It is also possible that others in my list may no longer support low current output.

I have some Pocket Juice power banks that are 2 cell and none of them support low current output. It seems any power bank with an ON switch doesn't support low current levels. I'm testing 2 Anker power banks and the first one turned off after about a minute.... the second one just turned off.... so I'm guessing the Anker power banks don't support low current as they too have ON switches. I have a few multi cell Ebay power banks (4 cells) that support low current but when I tried to buy another one I found they changed the circuit boards in them. Some power banks don't want to stay on even at 25ma current levels, some want over 100ma. 
I've used these dimming LED boards and power banks in a power outage and to light up the area around my computer as they run for weeks using 18650 batteries that I've scavenged from tool batteries and laptop battery packs.


----------



## maukka

Some Xiaomi ones have a force on festure. It’s activated with a doube click of the power button.

http://www.mi.com/en/pb10000pro/


----------



## subwoofer

Thanks for all the suggestions. So far though, many rely on a degree of luck as ebay chargers, which are often unbranded, seem to change, making certainty of features unreliable.



maukka said:


> Some Xiaomi ones have a force on festure. It’s activated with a doube click of the power button.
> 
> http://www.mi.com/en/pb10000pro/



So close, but the low power charging is for 2 hours only.

What I really want is a permanent on mode which is hard set with a slider switch, or other non-timed setting.


----------



## maukka

YZXStudio Powerbank can do it (and much much more), but it's a bit of a hassle to buy. Omnicharge as well, but it's expensive just for this purpose.

How about just a 5V boost converter from ebay connected to a bunch of 18650s in parallel?

edit: I'll go through some of my powerbanks and test them with minimal draw. Will get back to you.


----------



## maukka

Check out the Miller ML202. Been running now for an hour with minimal load. It also works as a UPS so the output doesn't cut out if you connect or remove it from a charger. HKJ's review.


----------



## KITROBASKIN

Does the Miller still require an unprotected battery of a certain length without a whole lot of wiggle-room?

The 102 and 106 are in stock at the link provided.


----------



## maukka

Yes, doesn't fit long protected batteries. 102 and 106 won't work since they'll cut off power on their own.

ML202 is in stock here: https://www.aliexpress.com/item/Fre...tery-mobile-phone-IPAD-tablet/1029639250.html


----------



## maukka

Found another one that works, but this may be one of those ebay class powerbanks you don't want. I've got three and they function well though.

Here's what I have and the same one in UK but with different branding.


----------



## subwoofer

@maukka

Thanks for the great information. The YZX one looks fantastic, but with the issues buying it, and the amount of building required, I'm less keen. If I ended up having to update the firmware it would end up as a big fail. Too many risks.

The Powercard looks good apart from only being 2500mah.

That ML202 is looking promising, but I don't have any good unprotected cells, which then means I've got to buy more. But then again, in total price it should still be a strong contender. Maybe I missed it, but I didn't see anything in HJK's review about low power unless it was this "When overdischarge protection trips the discharge current is below 0.03mA"

I'm going to double check the power draw I need to maintain and post that as well.

EDIT: So it is 14 mA I need to keep running.

Just tried a NITECORE F1 I have, and although it did turn on automatically, it cut out after 15s.


----------



## maukka

subwoofer said:


> EDIT: So it is 14 mA I need to keep running.



I tested at 12mA so you should be good. I'll let it run overnight to verify.


----------



## maukka

The ML202 was still on after 8 hours at 5mA.


----------



## subwoofer

Thanks, just ordered one off Aliexpress. I don't expect it to arrive for some time, but will post an update once I've tried it.


----------



## subwoofer

It's arrived, and none of the unprotected cells I have fit. Another order placed for some bare Samsung cells. Update once they arrive.


----------



## maukka

Strange. I measured and it looks like 65.4mm long cells should fit fine. I used a Sanyo 18650GA which are 65.25mm.


----------



## subwoofer

maukka said:


> Strange. I measured and it looks like 65.4mm long cells should fit fine. I used a Sanyo 18650GA which are 65.25mm.



I only have button top unprotected cells as I find them more universally compatible. My recovered cells which were truly bare flat tops, all died some time ago. I'll do a few measurements once the new cells arrive.


----------



## subwoofer

The new Samsung bare cells arrived and just fit - no room to spare.

Onto testing it - and the results so far, is that it is no different to any of the others. It will not stay on at the required 0.014A.

I have a couple of old 'Charge Doctor' USB current meters that are quite inefficient. Each draws 0.021-0.024A on its own to light up its bright display.

0.024A does not keep the ML202 on (this is the V5.0 version of the ML202).
0.045A does not keep the ML202 on.
and adding the clock as well oddly it doesn't all quite add up as this shows as
0.052A still does not keep the ML202 on

in fact using one of the Charge Doctors on my existing USB powerbank actually does keep it on, so the ML202 I received is worse than the one I had. And it seemed so promising.

Is yours the V5.0?


----------



## maukka

That's too bad. Mine is V4.0


----------



## subwoofer

And it gets worse:

So, only flat top bare cells fit; forget using any of your other 18650s.
I need to keep running at 0.014A, even at 0.05A this turns off.
I was getting 7.88Wh out of the PB and wondering why - it only uses the right hand slot for the USB output (when viewed with the positive terminal at the top).
You have to take out both cells and swap them to use the full PB capacity. The only thing about this is that you do know when you really get to 50% remaining capacity!
Even on one cell, it is outputting 2A, so that is quite impressive.

Considering I bought it for the low output current, and as a PB, this is a big fail for me.

Can I get a V4.0 from anywhere?


----------



## lipton5001

Hi guys, first post on here .. hope I don't walk on glass ..

I had a very decent powerbank which always outputted 5V, even with a 50MOhm load (multimeter). It did die out a couple of days ago ... and I've since learned that Samsung has a pretty dodgy record in powerbanks ... 

It's this one: https://www.amazon.de/dp/B00S8JYW7M/

Alongside those, the square DIY ones from China also always have the output enabled, however !!! Some of them use chips that don't completely cut the cell off when its voltage drops below the cutoff, and don't have any short circuit protection: so, these ones need thorough testing before being put into service:

1-cell-chinese: https://bit.ly/2nBMPHS
2-cell-chinese: https://bit.ly/2KNZpNo



Hope this helps!


PS: the Anker power banks .. although awesome, cut off at <65mA.


----------



## angerdan

The Just Mobile Gum Pro Battery Pack (4712176184434) did stay owered on until its energy has been drawn. 
ebay.co.uk/itm/Just-Mobile-Gum-Pro-Externen-Akku-4-400-mAh/202494217375

Unfortunately it has been discontinued several years ago like many other USB powerbanks with toggle switch.
bhphotovideo.com/c/product/814648-REG/Just_Mobile_PP_08_Gum_Pro_Battery_Pack.html
lygte-info.dk/review/Review%20USB%20battery%20box%204x18650%20%235%20UK.html

Also the precedessor did have an on/off switch. 
popgadget.net/2007/08/mobile_gum_for.php

But you can also use some Universal battery chargers to power their USB output with 18650 cells when they are inserted: 
lygte-info.dk/review/Review%20Charger%20Folomov%20A1%20UK.html
lygte-info.dk/review/Review%20Charger%20LiitoKala%20Lii-402%20UK.html
lygte-info.dk/review/Review%20Charger%20LiitoKala%20Lii-500%20UK.html
lygte-info.dk/review/Review%20Charger%20Efest%20LUC%20UK.html
lygte-info.dk/review/Review%20Charger%20Xtar%20WP2s%20UK.html
lygte-info.dk/review/Review%20Charger%20Xtar%20VP2%20UK.html
lygte-info.dk/review/Review%20Charger%20EFest%20Xsmart%20UK.html
lygte-info.dk/review/Review%20Charger%20ML-102%20V8.0%202015%20UK.html
google.com/search?q=%22USB+output%22+inurl%3Alygte-info.dk%2Freview%2F&ie=utf-8&oe=utf-8&client=firefox-b

Other solutions: 
enerprof.de/shop/batteries/power-banks/tensai-tb-13600-kfz-car-jump-starter-battery-charger-power-bank-48-96wh/
enerprof.de/shop/energy-cases/enerpower-ecd-500-energy-storage-unit-powerbank-500wh-li-ion-generator/


----------



## subwoofer

angerdan said:


> But you can also use some Universal battery chargers to power their USB output with 18650 cells when they are inserted:



It's funny you should post this as before I saw it, I found an old Xtar 2-cell charger with USB output (WP2 II). The USB output is switched on with a toggle switch. Not sure how efficient the output circuit is, so I'm giving it a runtime test.


----------



## Hopkins802

subwoofer said:


> I'm hoping the collective can point me in the direction of a USB powerbank which can be permanently turned ON. I have a USB powered clock which on the lowest brightness setting draws so little power, every single USB powerbank I own, automatically shuts off. I have to set it to the highest output for the current draw to be sufficient to keep the powerbank operating.
> 
> What I'm looking for is a powerbank that will keep the USB output live regardless of the current draw (like a mains charger would). I realise this means the calls will run down even with no USB load, but need to be able to decide myself when the USB socket is live.
> 
> I'd like it to be a reasonable brand (not a no-name hope-for-the-best type product) if possible.
> 
> Any ideas?




I have found a simple workaround that should work with just about any USB powerbank that has 2 output ports. It must have 2. I found this tiny USB stick LED light that draws just enough power to keep the power bank on. Then you can plug the device that draws very little power into the other output. Works like a charm! This is the type of thing I’m talking about: Sinywon Flexible Mini USB LED Light Lamp for Laptop, Keyboard, Power Bank, Portable Night Light or Reading Lamp (Pack of 3) https://www.amazon.com/dp/B0191S9I4K/?tag=cpf0b6-20

i just put some electrical tape over the tiny light, and you wouldn’t even know it’s there.


----------



## Lynx_Arc

lipton5001 said:


> Hi guys, first post on here .. hope I don't walk on glass ..
> 
> I had a very decent powerbank which always outputted 5V, even with a 50MOhm load (multimeter). It did die out a couple of days ago ... and I've since learned that Samsung has a pretty dodgy record in powerbanks ...
> 
> It's this one: https://www.amazon.de/dp/B00S8JYW7M/
> 
> Alongside those, the square DIY ones from China also always have the output enabled, however !!! Some of them use chips that don't completely cut the cell off when its voltage drops below the cutoff, and don't have any short circuit protection: so, these ones need thorough testing before being put into service:
> 
> 1-cell-chinese: https://bit.ly/2nBMPHS
> 2-cell-chinese: https://bit.ly/2KNZpNo
> 
> 
> 
> Hope this helps!
> 
> 
> PS: the Anker power banks .. although awesome, cut off at <65mA.



I have a few of the rectangular ebay DIY kits and all but the last one I bought would stay on, the last one had a different circuit board in it that wouldn't stay on with a very small load on it. Any power bank with an on switch or a separate LED light mode won't stay on when the load is too small.
I have 3 Anker power banks..... two of them are 3 and 4 cell banks with no LED light and both shut off and the 3rd is a 2 cell one with an LED light and it also won't stay on either. I've bought a lot of different cheap power banks off ebay from china and very few types of them have a circuit that stays on with low loads. 

I've also experimented with boost and buck boards plugged into power banks to power 3v and 9v devices to see how they work.


----------



## angerdan

Hopkins802 said:


> I have found a simple workaround that should work with just about any USB powerbank that has 2 output ports. It must have 2.
> I found this tiny USB stick LED light that draws just enough power to keep the power bank on.
> Then you can plug the device that draws very little power into the other output.


That's an good idea. But it uses more space and blocks the 2nd port. The USB LED stick is from Xioami: 
aliexpress.com/item/Original-Xiaomi-USB-Light-Xiaomi-LED-Light-with-USB-for-Power-Bank-comupter-Portable-Shining-Led/32744457452.html

Another option would be an small load (15-30 mA), which can be an cheap USB meter: 
ebay.com/itm/USB-2-0-Y-Kabel-A-Stecker-2x-A-Buchse-0-30m-30cm-schwarz-Y-Adapter-Power/173644238419
lygte-info.dk/review/Review%20Xtar%20USB%20current-voltage%20detector%20UK.html
lygte-info.dk/review/USBmeter%20safety%20tester%20J7-t%20UK.html

With an USB Y-cable, you can even charge 2 devices simultaneusly. 
ebay.com/itm/USB-2-0-Y-Kabel-A-Stecker-2x-A-Buchse-0-30m-30cm-schwarz-Y-Adapter-Power/173644238419




Lynx_Arc said:


> Any power bank with an on switch or a separate LED light mode won't stay on when the load is too small.


Please avoid full-quotes, this makes the thread less readable.


----------



## LowBat

If you're still looking for a power bank without auto-off, you might want to take a look at Voltaic Systems.

https://voltaicsystems.com/always-on-batteries/


----------



## subwoofer

LowBat said:


> If you're still looking for a power bank without auto-off, you might want to take a look at Voltaic Systems.
> 
> https://voltaicsystems.com/always-on-batteries/



Thank you, very helpful.


----------

