ATL by a few cents?
Previous deal a few months ago was $119.99:
https://www.ozbargain.com.au/node/836764
CamelCamelCamel.
160 watt-hours is the amount of energy that the battery can hold in total, not the rate at which it discharges.
25000mAh * 3.7v cell voltage = 92watt-hours = under the 100Wh limit of most airlines
Thanks for clarifying.
Also found this helpful post on the topic
20,000mAh is the rule of thumb in China. (20,000mAh/1000 * 5V) = 100 Wh.
Some manufacturers try to argue that 3.6V is the nominal voltage of the internal cells and Wh should be calculated as (20,000mAh/1000 * 3.6V) = 72 Wh.
I didn't want to have that argument at a security checkpoint…
I bought a ZMI QB826G 25,000mAh 3.63V 90.7Wh powerbank from Taobao. It has 240W in big text. And 90.7Wh in very small print. I figured that I would point to the 90.7Wh if needed.
I ended up taking the ZMI QB826G around China but rarely used it. I used a smaller Xiaomi 10,000mAh powerbank and had the ZMI as a backup.
I didn't run into any issues with 25,000mAh vs 90.7Wh vs etc while going through security.
100Wh is the limit for high speed trains in China.
Anything between 100Wh and 160Wh requires permission from an airline in China.
YMMV depending on each country.
Some manufacturers try to argue that 3.6V is the nominal voltage of the internal cells and Wh should be calculated as (20,000mAh/1000 * 3.6V) = 72 Wh.
The manufacturers are correct. Wh can be calculated for any voltage, but you need to know mAh at that voltage.
For battery, each cell has a mAh capacity rating at the nominal voltage. The nominal voltage is the voltage when the battery is at 50% capacity. It's generally in the 3.6V to 3.7V range for these style of cells, but depends on the cell chemistry and the charge and discharge voltage cut offs set by the manufacturer of the cells. (EG phones often use cells with a 3.85V nominal voltage)
For this ugreen power bank, it uses 5x 3.6V, 5000 mAh (5Ah) 21700 cells in series. So the Wh of each cell is 3.6V x 5Ah = 18Wh. With 5x cells in series, the nominal voltage of the entire power bank is 18V, and the capacity at 18V is 5000 mAh. So 90Wh. This rating is listed on the bottom of the power bank as "90Wh (18V 5000mAh).
To figure out the mAh at 5V, you divide 90Wh by 5V = 18Ah = 18,000 mAh.
The ZMI No.20 gives the individual nominal cell capacity - 3.63V. And total nominal capacity 24.5Ah. So 88.9Wh.
It also gives a second "nominal capacity" of 14000mAh, but this is listed with a voltage and current (5V/6A), and is the rated capacity of the power bank if draining it at 5V/6A.
Agreed :-)
I tried arguing that point with a friend that stood by 20,000 mAh being the limit when the actual restriction is 100Wh for high speed trains there.
Luckily I didn't have to argue with security.
A great power bank. And a bit more compact than most 100W or 140W options!
Efficiency does drop a little at sustained very high output (especially sustained 140W) compared to say the ANker 737 or ZMI No.20.
But sustained 100W or 140W is not a very common real world scenario, so typical efficiency for normal use is excellent.
My review and test results are here at TechRadar AU.
The 100W version is also on sale, its better value if you dont need 25,000mah
https://www.amazon.com.au/UGREEN-25188-20000mAh-Power-Bank/d…
Remember to check airline rules.
This powerbank seems to pass Qantas rules, as they allow up to 160w in carry on.
https://www.qantas.com/au/en/travel-info/baggage/dangerous-g…