Power banks for modern ultra low power laptops/tablets

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1

I have tried several of the higher power Anker power banks, but for a device only needing 5-10W on average they mostly suck…

Not that they don’t work, they do. However they seem to have BMS that in it self is a noticeable drain when only supplying 4-5W, like keeping a m-series MacBook air or iPad at their target 80% charge as you use it. They end up essentially self draining, and delivering only half of the stated power, sometimes even less.
I have found that more limited 20W 20Ah power banks actually delivers more than double the more actual Wh per charge than at least the 25Ah-27Ah laptop rated power banks I have tried so far.
The major drawback with 20-40W power banks is they take forever to charge. Often like 4-5h, vs the 200W+ power banks that charges in an hour or so. Is it impossible to create a high power BMS without noticeable self drain, or is this just a usage scenario that Anker has not bothered to take into account?

Does anybody here know of any power banks that can charge at 100W+, without self draining hugely on low output scenarios?

Sure some might say, dont trickle charge with them, drain your device and then quickly recharge it at a rate more suitable for “laptop” power banks, but that perspective misses a core point, power banks are cheap, and laptops are not, so why not have the power bank age out due to cycles instead of the more expensive device?

2

Bigger power-output capacity means bigger/more powerful components, with a higher self-discharge…

Check the powerbank best-buy-guides… they have more info than anyone here can give you

3

tweakers generally has good power bank coverage, but just as all the other sources I have checked, they fail to mention anything about how a power bank performs in low drain situations.

I might be missing something, but shouldn’t just putting the power bank at a static low power drain like 1 or 2 W and observe Wh delivered, then comparing that to what is delivered at higher more typical drains give a good idea of the BMS self-drain, or would that over simplify things, and miss something crucial?

4

They have stats for a 2A discharge (which is still 10W) … anything lower than that, you should probably not use a powerbank for (disconnect and use internal battery, or plug in a wall outlet).

5

at 15V my drain is closer to 0.5A so the 2A numbers don’t mean much unfortunately. And sure, with current power banks low power charging at 4-5W is highly inefficient, but still much chesper than having to replace the batteries in a laptop or tablet