I received this battery today and I have to say, I am unimpressed. I drained my iPhone 13 pro max to zero and charged it from the power bank to 80%. this drained the power bank down to 67%. My iPhone has a 4352 mah battery so technically, I should be able to charge it around four times before the battery in the power bank is drained.

Of course, there is the question of how much power it takes to charge the phone but I am very disappointed in the performance of this battery. Unless I have a defective unit, there is no way this is a 20000mah battery.

Caveat Emptor.

*Edit:

Ok, after doing some reading I've learned that the power efficiency dips the lower the wattage is on these batteries. Charging at 100 watts is more efficient than charging at 30 watts. Since my iPhone only has a 27 watt charging speed, the lower efficiency effectively brings down the mah substantially. As u/StopwatchGod pointed out, the efficiency for lower-wattage devices just isn't there.

So, I am assuming I would be much better off with a lower-wattage battery. My older 26000mah battery is USB A and does multiple full charges of our phones. I just want something like this but with USB C. I am returning this power bank and looking for something that has slower speeds but higher efficiency and is USB C. Pref by Anker

Thanks for all of your responses.

FINAL EDIT:

After doing some more research, it has become clear that virtually every power bank manufacturer is lying. whatever capacity you were buying, it is effectively half that in most cases. A quick Google search confirms this.

I am planning to get the Anker Prime 20,000mAh Power Bank (200W) but I heard the powerbank have issues to charge it to full 100% so instead of 100% it is actually 80% of power in the powerbank, has this be solved by Anker, the price is 131.347 US Dollar in my country, is it worth it as I will be using it to charge my laptop and other devices. The bigger version cost 168 US Dollar in my country.

A while ago I posted a thread with recent updates within the Anker products. Upgraded specs, mostly in terms of a) PPS-Range, b) added features like passthrough Charging or other minor changes. You can check this post here:
https://www.reddit.com/r/anker/comments/1h8vrrv/anker_charger_or_powerbanks_with_model_updates/

I made a new discover. I got the chance to get another Anker Prime 200W, 20.000 mAh Powerbank (A1336). I had this before since launch and can now compare both models.

The old model got some well deserved negative criticism for its low PPS-Range for a flagship Powerbank with only 3,3V-11V/3A resulting in around 27-30W max. for compatible devices. Also no Super Fast Charging 2.0 for Samsung phones. This new model has an upgraded PPS-Range 3,3V-11V/5A resulting in around 45W max for compatible devices. And yes, this means Super Fast Charging 2.0 aswell. It's a shame that they didn't use that opportunity to upgrade it to 21V/5A, since it's a 100W port after all. But still, it's a long overdue improvement regardless.

It's great that Anker made this upgrade, but it's also baffling that this is again nowhere near mentioned anywhere. The Powerbank itself and the packaging is 1:1 identical to the slightest detail. No chance to detect if it's the newer model or not.

I keep testing this model and will add any further improvements. One thing I can say it's identical in terms of Charging the Powerbank itself. It started with 100W but will throttle soon after around to 50W and stays there until fully charged. It's still the only Anker Prime Powerbank with some throttling issues. The 130W and 250W won't do that and charge with full 65W and 140W respectively. A full charge takes around 01:35h.

Mentioning the Anker 130W, 12.000 mAh powerbank: That model has the same old 3,3V-11V/3A PPS range and I also purchased another new model to compare it with my release one. That however still stays at 3A PPS. But: I might got an older model from Amazon and a better one is out there, who knows.

Also friendly reminder, since many people don't know that and it's also nowhere mentioned on the spec sheet: All three Anker Prime models are one of only a few powerbanks on the market supporting SuperVOOC, the private Charging protocol from Oppo, OnePlus and Realme. Up to 65W on all three devices. For the 12.000 mAh model it's on the USB-C and you need a SuperVOOC C to C cable. On the 20.000 mAh and 27.650 mAh model it's only on the USB-A and you need a SuperVOOC A to C cable.

I currently run a Realme GT 7 Pro, and those Prime models are a perfect match.