Using a power bank while it’s charging is something everyone has done at an airport, cafe, or any location with limited power outlets. This can be a smart move when traveling, since it ensures your almost dead device, whether it be a phone, tablet, or set of headphones, charges while your juiced out power bank also gets enough power to recharge them later down the road. However, not all power banks are smart enough to separate the process of charging while also being charged.
This is usually an issue if you’re using cheap power banks, because you’re simultaneously charging while discharging their battery. This causes the power bank to generate excess heat, which is something known to shorten the lifespan of lithium-ion batteries. Heat is also the biggest reason why you shouldn’t use your phone while charging it. While some power banks will disable the ports when charging to ensure this doesn’t happen, if you’ve noticed yours doesn’t, you should ensure it has a feature called passthrough charging. Otherwise, disconnect the other device and let your power bank charge peacefully.
Making sure your power bank can safely charge while being charged
Check your power bank or its spec sheet for words like “passthrough,” “simultaneous charging,” or “charge through.” Luckily, several affordable power banks support passthrough, meaning yours could, even if it’s not expensive. If it’s supported, your power bank has a dedicated controller chip and circuitry to bypass the battery and protect its internal components when charging. In a nutshell, the current will go from the outlet to both the device and battery directly instead of passing through the battery first.
One caveat is that even if the power bank supports passthrough charging, both devices will charge at a slower rate since the controller chip is splitting the current between them. The bigger problem, however, is that heat is still an issue because of this (albeit to a lesser extent than if it didn’t have passthrough). Since lithium-ion batteries generate heat throughout the charging process, they will generate more and more of it the longer they’re in this extended charging period. This can be dangerous at higher levels of charge (above 80% and above).
So, even with passthrough charging, the potential for excess heat to degrade the battery exists. Use it sparingly and stop when the power bank’s battery reaches 80% to prevent shortening the battery’s lifespan. Also, be sure to use high-quality cables (you don’t want to use a slow charger in this scenario) and that your power bank is well-ventilated to prevent added heat buildup.
