TL;DR - try heating up your battery pack with a hairdryer for a minute then putting it on the charger and it might start charging again!

Introduction

Got a dead USB battery bank?
Put it on the charger for hours and it still won’t display any lights when you press the power/battery level indicator button?

I know I’ve got several - I forget them in my backpack after a trip and the battery depleted so much they wouldn’t charge anymore. It’s so frustrating the next time I’m packing for a trip only to find out my battery bank is dead! But don’t worry, there’s a quick and easy fix that might revive your dead battery bank.

Disclaimer

First, know that this is dangerous. As with any advice you hear on the internet, use your best judgement.
I do not recommend doing this if you’re not knowledgeable and comfortable with the risks. It involves heating up LiPo batteries which holds a risk of creating a fire that cannot be extinguished with water or a fire extinguisher.

The Fix

Heat up your battery pack with a hairdryer for a minute or so until pressing the power/battery level indicator button causes the battery level to display (presumably it will be at 1 bar). Then, immediately plug it into a charger and it should start charging again. That’s it!

Why It Works

Typically, the integrated circuit (IC) that charges the battery inside the battery pack will disable charging for safety reasons if the battery voltage is too low. Heating up the battery pack with a hairdryer raises the battery temperature which increases the battery voltage, allowing the IC to enable charging again.

If the battery has been sitting in a discharged state for a long time, the battery may have slowly self-discharged to a point where the voltage dropped below the threshold for the IC to enable charging. Heating up the battery pack raises the battery voltage enough to enable charging.

If the battery pack has been discharged for too long (multiple years), it may be too far gone for heat alone to bring it back up to voltage, but it could be worth a shot :) Depending on how adventurous you’re feeling, you could try disassembling the battery pack and “jump-starting” it with a power supply, but I can’t recommend that method unless you already know what you’re doing, in which case you won’t need the instructions ;)

Conclusion

I’m 2 for 2 reviving my dead battery banks with this method. Did this fix work for you? Leave a comment below! If you have any questions, feel free to ask. Thanks for reading!