Most power banks will automatically turn off their USB ports when the power/current being drawn is lower than a certain value. This makes it impossible to run low-power devices on a power bank, such as a Raspberry Pi Pico, small microcontrollers or even charge your AirPods.
...until now! This is a USB KeepAliveKit which does exactly that - it keeps your power bank 'alive' by pulsing a small amount of current (via a 555 timer - neat) through the USB port. The pulse combined with the low-current draw from your end device will keep your power bank alive.
You plug one end of this into your power bank, the other end into your device, and there you have it - an easy, reliable mobile power source.
This is the kit form version which requires soldering and assembly - great for those who want to tweak the resistor values for their specific power bank or end device, or even just those who like a cheeky little soldering project. A fully-assembled version is available here, and we also stock an ultra-compact USB-C version.
Your mileage may vary! We can't test every power bank out there, however Colin from Eplop has created these KeepAlives with values that should work with most.
The pass-through should work with all devices as the data lines are unaffected. With the resistor values chosen on its own it should not keep most power banks alive, but combined with a very low-power device, it should be enough to stop the power bank from powering off. Since the resistors are easily changed in this kit version, it can be modified to meet your needs
From the Designer
When I'm working on small projects, I like to power them from a power bank or a similar item. Sometimes, the device draws such a small amount of power that it shuts down the power to the USB port as it thinks the device is off.
This device that I've designed will stay on by pulsing the power line to ensure that it doesn't shut down. It utilizes the 555 timer in an Astable circuit. With the configured resistors and capacitor, there is a 50% duty cycle which equates to roughly a 10mA draw with a pulse of approx 130mA. Combined with the draw of the device, this shall be enough to keep the power bank active. The data lines are directly connected and unaffected. - Colin Hickey
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