Question How dangerous is slow charge to a laptop from an external battery?


Aug 5, 2016
Hello. I just bought a brand new Asus Zenbook 13 OLED(ux325ea). its a really good laptop. Thing is, I use some demanding software and the battery is dead in like 2-3 hours while Im not home. I used a Xiaomi Mi Powerbank Pro 3 which has PD of 45w through USB C. The laptop`s charge is rated at 65w fast charge.

The idea is the external battery works when charging this laptop but the problem is Windows is telling me its detecting a slow charge and advises me to use the original charger.

Is it dangerous for the health of the battery to charge it slowly with this external battery? And why?
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Sep 2, 2021
You may want to use better powerbank, with 65W PD.
You can also build your own. Get some de-packed LI-ION cells, you can get unused cells for like 1-3$ on many places in the Net, some seller are even offering to solder nickel bars so you will get ready made power pack.
You will need buck converter or boost converter. First is a step-down conv. and lowers voltage, 2nd is step-up and raises voltage (using current to do that). You can make a 8S(series)4P(arallel) pack so it has ~32-30V (when fully charged) and 4x designed battery capacity. Usually 2000-3500mAh in case of 18650 cells or even 5000mAh (5Ah) if you use bigger, 26650 or 27000 cells like LG M50. so 4x3,5 Ah=14Ah. Add buck converter capable of 70-100W on the output with 19-20V (depends on you laptop power supply voltage) from ebay/ali and some package, maybe make a flat battery pack with two universal PCB (the one with many small holes in it, each on the side to make it stiff and safe, laminate it or cover with some tape or foil and ypu are good to go :) Lets suppose laptop needs 2-3A per hour of work when under heavy load. That should give you extra 4-8hours. Please mind that pack consisting of 32 batteries is not a small and light thing :)
Hope you will find it helpful.



From what I understand about batteries, fast charges wear them out more quickly due to the heat increase. Likewise, I'd think that slow charging is actually healthier for the battery in the long run, since the battery won't heat up too much from the charge.