USB Electronic Load to prevent power-bank low-current shut-down
USB battery packs are a convenient way of powering low power USB devices such as WSPRlite. Unfortunately many USB battery packs switch off (go into a sleep mode) if the current being drawn is too low. This means that your device works for a few minutes and then stops. Often just a few extra milliamps current draw will keep the battery pack alive. There are various circuits on the web that give a pulsed load which works with some battery packs - but unfortunately our tests have shown that such circuits don't work reliably with all battery packs.
Our solution is a variable electronic load. We have designed it to be very simple to use. Just plug it into your battery pack and increase the current until battery pack stays on reliably (6 - 150 mA). Depending on the current that your powered device takes that may be a little as a few milliamps. An on-board LED indicates if the battery pack is live. The load supports a standard USB data connection. USB plug and socket for easy in-line connection. Clear heat-shrink sleeving is provided to protect the unit in the field.
Available as an easy-to-make kit suitable for a beginner or fully built and tested. Note that the built unit is supplied encapsulated in clear heat-shrink sleeving.
Easy to use
To use, just plug the Keep-alive load between your battery and item to be powered and adjust the blue potentiometer on the unit with a fine screwdriver. Set it fully clockwise at first (maximum current) and gradually decrease the current until the battery pack just cuts out. Then increase the current until the battery pack stays on reliably. That way you only draw just enough current for reliable operation - increasing the life of your battery.
Instructions are available HERE!
Also available from our international agent(s):
Frequently asked questions
Why not use a pulsed design?
We initially tried a pulsed design, but found that it did not work reliably with all battery packs. We believe this is because some battery packs measure their output current at infrequent intervals. This is fine if the measurements are guaranteed to occur during the pulses often enough to keep the battery pack turned on. But depending on the frequencies of the measurements and load pulses, the measurement times may eventually line up with the low current times for long enough that the battery pack turns off, at an unpredictable time after powering up that depends on the difference between the frequencies, the duty cycle of the load, the turn-off delay of the battery pack, and the initial offset between measurement times and load pulse times. This means that even if a battery pack initially appears to work fine with a pulsed load, it may shut down at some random time later, and it is difficult to determine in advance whether that will happen until it suddenly does.
Since the inner workings of battery packs can vary widely between different models and are usually not well documented, the only way to be sure that a USB keep-alive load will work correctly with all battery packs is to use a constant current load. This wastes more power than a pulsed load, but is more reliable.
21 Reviews Hide Reviews Show Reviews
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•USB battery pack keep-alive load
This does exactly what it says on the box. It works perfectly I found it easy to build and I have very little soldering experience
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USB Battery Pack Keep-Alive Load
Quality product, and works as intended.
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USB Battrry pack keep alive load
An excellent product which totally did the job designed to do. Works well and easy to use.
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Works a treat
Well designed circuit with quality PCB works a treat thanks
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Used with GPS Tracker- Good
I bought the pre-asembled version to power a Rewire 102 Nano GPS tracker from a 20,000mAH USB power pack in the boot of my car. It does indeed keep the power pack active so the tracker stays charged and working. However, even with a 20,000mAh per pack the tracker only runs for about 72-96hrs, so I have to remember to swap the powerpack regularly and couldn't rely on it to monitor the car while on holiday for example. I don't know if the main current draw is from the tracker or the device, but I was hoping for a bit longer battery life. Second, when it is plugged into the power pack with a usb cable supplying the tracker the whole thing does feel little fragile and vulnerable to snapping - I've put it in a padded case and its ok so far, but I would be cautious about relying on it for something like trekking. Great device if you can live with these limitations.
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Best Product and Culture
I bought two, work excellent. Packaging is solid. Shipping is quickly. I needed help, get response at once, even the clock show 16:30. The owner still at work after 4:00 pm. He has a nice and helpful attitude. Documentation can be found on Sotabeams website, well writing. I did not only get excellent products, I get the best business culture in the market included. Very satisfied customer.
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Works perfectly
This is the second unit I have bought, as I totally bodged the first being a totally incompetent with a soldering iron ! Took advice and bought a decent soldering station with variable temperature, and a Helping Hands unit with magnifier and LED's. Instructions easy to follow, and took my time building it. Instructions say about 20 mins, but I was in no rush, and checked each and every soldering joint. took me about an hour to build, BUT it worked perfectly first time. Heat shrink protects the unit to some degree. Now my USB battery pack switches off when I want it to. Excellent kit, and now can't wait to build my Low Pass Filter kit for 40/80/160m.
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Perfect! Simple yet easy solution to Power Pack use.
Having bought the WSPRLITE and now getting round to setting it up I suspected that my 10,000 mAh power pack, originally bought to supply my Iphone on a 7 day cross country wild camping lone trek, would drop out. It does sometimes. I saw this simple device and bought it. Arrived earlier today, easy to build (good instructions) and set up. Brilliant with simple heatshrink protection. I cut a small window for the pot adjuster and for the LED (brighter without the heatshrink covering it). Labelled up and put in my portable pack ready for my first try out portable before winter comes.
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Excellent to stop the auto shut off of my Power bank battery.
Easy to mount and with good instructions, In my case, my 13.000 mAh USB Power bank battery , jumped in auto-shut down power mode, each time that WSPRLite kept in stby cycle. After adding that kit between and adjusting it to around just 10mA , it solves the problem, perfect !!!! Note : together with the kits parts , comes a little transparent plastic part it is not a sheet, it's a SLEEVE. Open it and slide it over the unit then shrink it in place. Apply hot air gun to shrink it . No enclosure is needed.
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Nearly a must have for the WSPRlite
I bought one of these with my WSPRlite kit and didn't build it at first. I thought my fairly expensive Anker battery packs would power the WSPRlite just fine. I was wrong. The WSPRlite would run for the good part of a day or less. Eventually it would always turn off. I really wanted to believe that the problem was with the WSPRlite because the Anker battery packs work well with everything. They work well but I've never tested them with something like the WSPRlite that has such a low current demand. This device simply puts just enough load on the battery pack to keep it from turning off. Don't expect a glaring red LED, the LED will be on but not super bright. I believe that's by design in order to keep this device from loading the battery pack down too much. It's a quick and easy kit that only takes about 15 minutes to build. If you're ordering a WSPRlite, just throw one of these in your cart so that you have it....just in case.
