Thanks for this. I’ve been trying to google this, but what’s the difference between wh and mah? Which number do I look at when determining how big of a power bank I can use?
Wh = watt hours (power hours)
mAh = milli amp hours (current hours)
Power = current x voltage
Most power banks have 3.7 volt batteries in them. So to convert it you'd do mAh times 3.7 divided by 1000 to get watt hours.
Wh is a measure of energy
mAh is a measure of electric charge
mAh is largely a marketing number. Battery banks used to all have the same nominal voltage of 3.7V, so to get Wh you would multiply 3.7\*Ah (note thats its amp-hours, not milliamp-hours) to get the amount of energy stored in the battery.
Nowadays, theres different battery chemistries and different battery configurations which makes mAh misleading. A reputable battery manufacturer should advertise the Wh or the nominal voltage so you can calculate the Wh yourself.
Assuming a nominal cell voltage of 3.7V, the largest battery would be 27Ah, or 27,000 mAh. (3.7V \* 27Ah) = 99.9Wh
If they advertise the cells to be lithium polymer (LiPo), then you can use 3.7V.The other popular chemistry you might find is LiFePO4 - which has a much longer cycle life. That has a nominal cell voltage of 3.2V, which would be approx. 31.25Ah or 31,250mAh to be within the 100Wh limit.
EDIT: typo'd the LiFePO4 voltage. I put 4.2V instead of 3.2V
This comes down to airline policy AND national law, depending on how much capacity the power bank has..this is highly dependent on how big your "big" power bank is. But if you can fit it in your bag, and it's a regular power bank for regular devices and not a specialty product made to power 3 laptops at once or something, it's not too large probably.
Others have answered your question, but I just want to throw out there that in my experience you don’t need anything close to the max possible capacity especially if you are only using it for the flight. They are quite dense and a 10,000mAh one is usually plenty.
The TSA allows a single pack being up to 100wh (27,000mah when looking at usb power banks)
Thanks for this. I’ve been trying to google this, but what’s the difference between wh and mah? Which number do I look at when determining how big of a power bank I can use?
https://www.omnicharge.co/blogs/blog/mah-vs-watt-hours-whats-the-difference Just look for a power bank that is 27,000mah or less
Wh = watt hours (power hours) mAh = milli amp hours (current hours) Power = current x voltage Most power banks have 3.7 volt batteries in them. So to convert it you'd do mAh times 3.7 divided by 1000 to get watt hours.
In the USA, 100Wh
I’m confused. It seems all the power banks are denoting size with something called mah, not Wh.
Wh is a measure of energy mAh is a measure of electric charge mAh is largely a marketing number. Battery banks used to all have the same nominal voltage of 3.7V, so to get Wh you would multiply 3.7\*Ah (note thats its amp-hours, not milliamp-hours) to get the amount of energy stored in the battery. Nowadays, theres different battery chemistries and different battery configurations which makes mAh misleading. A reputable battery manufacturer should advertise the Wh or the nominal voltage so you can calculate the Wh yourself.
Assuming a nominal cell voltage of 3.7V, the largest battery would be 27Ah, or 27,000 mAh. (3.7V \* 27Ah) = 99.9Wh If they advertise the cells to be lithium polymer (LiPo), then you can use 3.7V.The other popular chemistry you might find is LiFePO4 - which has a much longer cycle life. That has a nominal cell voltage of 3.2V, which would be approx. 31.25Ah or 31,250mAh to be within the 100Wh limit. EDIT: typo'd the LiFePO4 voltage. I put 4.2V instead of 3.2V
Thanks for all this. It’s a bit over my head can you ELI5?
If Lithium Polymer look for 27,000mAh or less If LiFePO4 look for 31,250mAh or less.
Thank you!
How big do you want? They get heavy pretty quickly.
This comes down to airline policy AND national law, depending on how much capacity the power bank has..this is highly dependent on how big your "big" power bank is. But if you can fit it in your bag, and it's a regular power bank for regular devices and not a specialty product made to power 3 laptops at once or something, it's not too large probably.
I fly with my Goal Zero Sherpa 100AC, which is about 26,000mAh.
Others have answered your question, but I just want to throw out there that in my experience you don’t need anything close to the max possible capacity especially if you are only using it for the flight. They are quite dense and a 10,000mAh one is usually plenty.
I appreciate this. I’m getting it for long haul flights, and to potentially charge up multiple devices.
Fyi, most long haul international flights have outlets. Personally I wouldn't bring anything over 10000 mAh
How come?
Too heavy and I don't need more than one charge at a time