USB battery pack keep-alive load

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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. 

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13 Reviews Hide Reviews Show Reviews

  • 5
    Perfect! Simple yet easy solution to Power Pack use.

    Posted by Rachael M1AYG on 7th Sep 2017

    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.

  • 5
    Excellent to stop the auto shut off of my Power bank battery.

    Posted by EA3HQJ on 20th Jun 2017

    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.

  • 5
    Nearly a must have for the WSPRlite

    Posted by Curt on 20th Jun 2017

    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.

  • 5
    Quality kit, works a treat

    Posted by Alan VK6CQ / VKØLD on 21st Apr 2017

    Well designed circuit with quality PCB & components. Easy to build and works a treat. 21 days UK to Aus by ordinary airmail.