I have recently bought at Anker 521 “Power station” to charge my drone batteries when away from a mains supply.
I have a number of good quality USB C cables (one is Anker 100w - https://amzn.eu/d/bhs9lyk), and when connected to the DJI charging hub, delivers 17w
However, if I use the USB C cable that came from DJI, I get 21w (see image).
I assume the charging hub is limiting the power being drawn, but any ideas why the higher quality cable from Anker does not deliver the same as the DJI cable?
Do you have a fast charger (plug) that you can plug into the unit to see what it delivers ?
What are the specs of the USB C port on the Anker
The hub will switch wattage constantly as it charges but should max out at 36w at times
But it could be and is more likely the USB C port
Anker claim “ 60W USB-C PD Output” so should have no problem.
You need the full specs, the voltage and watt output, it may not be compatible with the DJI charge hub to pull the max 36w
Does this help?
USB-C Output 5V⎓3A / 9V⎓3A / 15V⎓3A / 20V⎓3A (60W Max)
Do you mean a fast charger that I can plug into the mains socket on the unit?
Now look for the specs of the charge hub
So looking at the spec on the DJI web site, it says
Recommended Charger: DJI 30W USB-C Charger or other USB Power Delivery chargersInput: 5 V, 3 A/9 V, 3 A/12 V, 3 A
Charging Time: Three Intelligent Flight Batteries can be fully charged in about three hours.
I have just charged up my 3 batteries and it took about 3 hours, so the overall speed seems about right, but I noticed that the first battery (using the Anker cable), took 68 mins, but the other 2 (using the DJI cable) took 59 and 57 mins, so the DJI cable is clearly faster for some reason??
The charger will negotiate the charge current, with yours you can charge at a max of 27w (9v 3A) the hub can go to 36w (12v 3A) but your Anker cant deliver that
Charge them again when empty and you should see it pull 27w at some point
This was mine before
Started at 36w and slowly dropped to 3w when fully charged
What Wayne said.
My EcoFlow is bad with DJI stuff for some reason, sometimes fast charges sometimes not
Use the 3 pin socket with a decent plug
Thanks for explaining that … I’m gradually getting to understand this stuff more 
I never saw it go over 21w (based on info on the display but also using a cable similar to the one you have in the image (Ocetea USB C to USB C Charger… https://www.amazon.co.uk/dp/B0BJZ5WY9J?ref=ppx_pop_mob_ap_share)
Once I have flattened the batteries again, I will try with my 60w charger and see if I can get some clarity.
I had the exact same problem with the Anker 521 with the dji stuff, i just use a plug charger, seems to work using that 
You mean you plug your mains charger into the 13A socket on the Anker unit?
Yes see what speeds u get
I assume that this way will be less efficient, but maybe quicker?
Just coming back to my original question, any ideas why the DJI cable is quicker than a couple of good quality alternatives?
I often use a 4 way trailing out of mine, charge everything at once.
Pass 
I read somewhere that using a third party charging hub like this one https://www.amazon.co.uk/LYONGTECH-Two-Way-Batteries-Charging-Accessories/dp/B0BS3574M1 instead of the DJI hub would allow the batteries to charge at full speed from the Anker power station. Unfortunately I can’t find the article where I originally got that information.
I’ll give that a go once I have some flat batteries 
to try it with
