On Using a USB Battery for a Portable Project Power Supply

RE: On Using a USB Battery for a Portable Project Power Supply

Hot_Spring_Soaker — Wed, 11 Jun 2025 05:50:32 GMT

I have a Silver XPB15031S as well. I have not used it for a long time. It appears to be dead.
When I attempt to charge it, the LED's cycle red then blue nonstop. I suspect the battery inside is bad.
I'd like to repair my power bank but I'm unsure how to disassemble. I suspect there is a screw under the label on the end opposite the USB connectors.
Does anyone have any advice. I understand the need to be careful when working with a Li-Ion battery due to the risk of fire.
Is there a way to resurrect a Li-Ion battery? I've done it with Ni-Cads by briefly zapping them with a low voltage high current source to remove shorts and charging them afterwards.
Any guidance would be welcomed.

RE: On Using a USB Battery for a Portable Project Power Supply

colporteur — Sun, 19 Jul 2020 00:27:38 GMT

The circuit is overhead (wasted energy) on a battery supported system. How much battery life is lost due to the circuit?

I got a battery like your silver unit in a swag bag. I wanted to know how long it would power a Pi3B+ running a GPD module. I can't recall the time the Pi ran, I want to say 8 hours but I was using another battery with a higher capacity so I may have switch the values. The battery life was sufficient to turn a Pi into a portal GPS recorder. Yeah, no need to purchase something just for testing.

What would be the lost of uptime due to your circuit? I realize the keepalive is small but it is still lost energy.

RE: On Using a USB Battery for a Portable Project Power Supply

botsmaker — Sat, 18 Jul 2020 04:09:13 GMT

Today I made one using a Picaxe 08M2 for the timing and used it to pulse a 2N4401 transistor with a 10 ohm resistor. I needed to use a battery pack to power a Arduino Uno with Logger (it wants 20 ma). Works pretty good with 10 millisec pulses every 5 seconds. After building it, I could have just added the resistor and transistor to the Arduino shield circuit itself and have the program pulse the resistor for me. With the Picaxe, only a few lines of code are required.

It seems the bigger the pack, the more load is required. I tried setting up the timing for my Powobest Solar Bank and couldn't get enough current to trigger it. Gave up on it as it would waste too much power.

Good project idea, glad you posted it.[View:/resized-image/__size/679x900/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-5984376b-1392-4430-ac17-1582c495d83d/contentimage_5F00_188818.bmp:679:900]

RE: On Using a USB Battery for a Portable Project Power Supply

koudelad — Mon, 24 Feb 2020 19:33:10 GMT

Thank you, John, for this interesting blog post. My experience is the same - power banks are not usable as UPSes nor power supplies for low current loads.

I just realized I can test my power banks using a programmable DC load to find out the limits and cutoff times! It should work easily and automatically.

RE: On Using a USB Battery for a Portable Project Power Supply

bryansy — Mon, 24 Feb 2020 15:36:13 GMT

Has anyone have this problem with a power bank? This is an el cheapo power bank. I assume it senses if there is no load by cutting off power every 10 seconds and seeing if voltage goes down. If voltage goes down it restarts the buck converter. But it goes down for as much as 40ms and thats enough to reset a cpu.

RE: On Using a USB Battery for a Portable Project Power Supply

msmurphy — Fri, 08 Mar 2019 10:07:41 GMT

Thank you so much for this incredibly helpful post. You saved me $36 and taught me everything I need to use my new battery pack. Before you poke fun at me, let me explain. I'm not an idiot, i know how to use a battery pack without an instruction manuel, but I've had friends who said they shortened the life span of many battery operated objects by using the wrong charging method. Whether that is true or not, I can't say, but I like to read and learn new things. Can you tell me what the 3 blue lights on black indicate?

RE: On Using a USB Battery for a Portable Project Power Supply

aspork42 — Wed, 27 Feb 2019 04:50:04 GMT

I got tripped up trying to use a USB battery pack as a simple UPS for a RaspberryPi project. I had about 1 week to throw together a security system with OpenHab and Z-Wave sensors; then drive from Milwaukee to Detroit to install it. I did a simple test of plugging in both sides of the battery (charge side and load side) and was able to verify that the power output was indeed, uninterrupted. However, what I didn't check was if the battery was actually charging.

[View:/resized-image/__size/620x827/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-5984376b-1392-4430-ac17-1582c495d83d/2480.contentimage_5F00_188816.jpg:620:827]

(drywall dust in the background from the security camera install that I also did on this trip)

I set the system up and left again for Milwaukee. A day or two after getting home, the system went offline and I had to get the mother in law to bypass the battery and plug in directly to the wall. So, this particular battery pack doesn't support "UPS Mode". I have since found that there are some available that can work like this.

RE: On Using a USB Battery for a Portable Project Power Supply

dubbie — Sat, 16 Feb 2019 11:06:35 GMT

I have been thinking about using these power packs for my projects so this has been a timely set of informative comments that is bound to be of great help to me.

Dubbie

RE: On Using a USB Battery for a Portable Project Power Supply

neilk — Fri, 15 Feb 2019 12:13:13 GMT

Hi John

I read this at the time you posted it, but it didn't stick in my mind because I had no interest in using USB batteries and didn't even own one for charging my mobile phone!

In my latest Blog I've reported on how I was tripped up trying to power a project using such a battery, because my project doesn't draw enough current!! If I's remembered your post, I might have bought a USB battery that worked for me!

My memory has got so bad these days!

Neil

RE: On Using a USB Battery for a Portable Project Power Supply

genebren — Mon, 15 Oct 2018 14:16:40 GMT

Very interesting investigation and work-around. I really enjoy seeing your process and approach in solving a problem. Here is another solution, you could build your own USB/battery source. In my development of WalkyII, for the Movers and Shakers project14 competition, I built my own USB/battery source. Being used as a power source only, I never thought of adding a low current drain shut off, so that should not be a problem for your uses. The circuit could be further optimized, but hopefully the basic elements of the circuit could be turned into something that might help you.

The schematic is within this blog: Walky the Biped Robot - Power pack

Good luck!

Gene

RE: On Using a USB Battery for a Portable Project Power Supply

Gough Lui — Mon, 15 Oct 2018 06:09:30 GMT

As an experienced power bank tester - I've come across a wide variation of types, but I haven't really taken the time to test the shut-off behaviour. I have found some that:

Have high quiescent current but maintain a 5V output at all times, until the battery is depleted and it abruptly switches off. Unfortunately this type needs regular topping off with the charger or it'll be flat when you come to use it. Don't store it with your keys in your bag either, otherwise nasty things can happen.
Have microcontroller-based switching control and can be turned on/off manually with a button - some of these types have an output that is off (0v) when turned off, others are more like the latter.
Have integrated boost chips that turn on whenever sensing a load greater than a given current - this type has an output that is "battery level" (3-4.2v) when the boost is not engaged, thus if your circuit can work on "unboosted" Li-Ion voltage, it will continue to work. Other appliances (e.g. cheap USB lights) tend to show reduced performance (e.g. dim/slow/etc). Charging is done by basic "linear" regulator chips (e.g. TP4056) which is slow and inefficient.
Have integrated power-bank controllers - these tend to use one coil but can boost for output or buck for charging, just not both at the same time. Issues are similar to the above.
Have more intelligent Qualcomm Quick-Charge capable controllers - some are dual-way QC capable resulting in buck-converted charging and boost-converted output. For QC2.0 power banks, some tweaks on the D+ and D- lines can signal for 12V, 9V, 5V output from most power banks, whereas for QC3.0, this can be commanded in 0.2V steps between about 3.6V - 12V. These are much more expensive and more efficient, but some will have shut-off behaviour.

Now that I've mentioned this - I suspect some units can't be fooled by short pulse loads as they only sample the load resistor output infrequently and aren't really integrating the current over time. If your pulses aren't long enough to overlap with the sample time, then there's basically as good as no load at all. I suspect some of the "microcontroller" based units might be fooled by changing the resistor, but at the risk of breaking overload protection/voltage regulation feedback (as some have a "voltage slope compensation" function that boosts the voltage higher under higher loads to compensate for cable drop).

But more than this, sometimes, you just need to find a model you like and settle down. The last one I used and I still use regularly is the Xiaomi Mi Power Bank Pro (QC 3.0) power bank. The QC feature is quite nice for phones, but if you build something like this, you can turn it into a 3.6V-12V variable power source up to 1.5A. Furthermore, if you read the manual, there is a low-current charge mode too - double-press the power button and it locks itself into supplying 5V regardless of current load, but only for two hours. This mode is intended for charging accessories such as Bluetooth Headsets and Smart Band Fitness Trackers which have <40mAh batteries and even lower charge currents. I believe some other power bank manufacturers are beginning to offer this mode.

- Gough

RE: On Using a USB Battery for a Portable Project Power Supply

dougw — Mon, 15 Oct 2018 04:51:30 GMT

Nice solution [mention:f80b53cee57c44bc9d7c577d07d7c791:e9ed411860ed4f2ba0265705b8793d05].

I have some units that look exactly like your silver unit except they are black - and they stay on indefinitely - until the power button is pressed again. There is a little blue LED that illuminates when they are on - maybe it is enough of a load.

I have another white one (from the Dollar Store) that has no power button, when it sees a load it turns on with a 5V output - no LED. When the load is removed it tuns off.

RE: On Using a USB Battery for a Portable Project Power Supply

mcb1 — Mon, 15 Oct 2018 04:16:54 GMT

Nice find and solution.

I have a couple of these 'battery banks' and they were obtained for somethign and then put aside.

I never get to do any testing, so I suspect many of them are the same.

I wonder if you can swap your inverter (CD 40106) for a simple transistor ... and then even better make it using a small uP (ATTiny85 perhaps).

Cheers

mark

RE: On Using a USB Battery for a Portable Project Power Supply

fmilburn — Mon, 15 Oct 2018 03:52:40 GMT

Hi John,

Nice implementation and tests. I wonder if silver would reset its clock and work if the pulse was longer than 3 milliseconds. I will look into doing some tests of my own. Great post!

Frank