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ROMOSS 40000mAh 18W Fast Charging Portable Power Bank $36 + Free Shipping
$35.99
$59.99
Romoss via Amazon [amazon.com] has ROMOSS 40000mAh 18W Fast Charging Portable Power Bank (PEA40) for $59.99 - 40% off coupon on item page = $35.99. Shipping is free.
Specifications:
Specifications:
- Black
- 18W
- Connector Type: Lightning Micro USB, USB Type C
- Battery Capacity: 40000 Milliamp Hours
- Compatible Devices: IPhone 13/13 Pro/13 Pro Max/XS/XR, Pixel 3/3XL, Galaxy S10/S9/Note 9/8
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Well I guess it might be able to maintain the battery level at least.
Last time I ordered this - it was super light, had rattling stuff inside, and definitely did not match the capacity by a long shot.
but people will get downvote us for ruining the party - so carry on.
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It seems many brands advertise the mAh based off of internal voltage of the cells inside the power bank. (which can be a sort of a sneaky way to market a product if people are thinking of 5 volts)
If you want to get a more accurate mAh rating for your devices, you need to know the voltage you are going to draw from the power bank and the watt-hours the power bank actually has.
With many manufacturers, you have to look up the product manual or go to the product's page on the manufacturers website to find what the watt-hours of the power bank are.
So for this power bank the website says it is 148 watt-hours (https://www.romosspower
That puts this bank at 40,000 mAh at 3.7 volts
(148) x (1,000/3.7) = 40,000
If you want to find the mAh rating for 5 volts it would be:
(148) x (1,000/5) = 29,600
Looking at an Anker product, for example Anker 525 Power Bank, they advertise the same way: 20,000 mAh
That looks like at 3.6 volts because the rated watt-hours is 72 according to the manual.
for 5v it would be 14,400 mAh
Someone please correct me if I've done something wrong.
You would have to measure one of these power banks and see if the rated watt-hours is correct. I don't have this Romoss product, but I do have the PHP30 Pro model sold as 111 watt-hours. It's pretty close to that from my testing. Reviews mention these things sometimes swell up. Mine hasn't yet and has worked well so far.
It seems many brands advertise the mAh based off of internal voltage of the cells inside the power bank. (which can be a sort of a sneaky way to market a product if people are thinking of 5 volts)
If you want to get a more accurate mAh rating for your devices, you need to know the voltage you are going to draw from the power bank and the watt-hours the power bank actually has.
With many manufacturers, you have to look up the product manual or go to the product's page on the manufacturers website to find what the watt-hours of the power bank are.
So for this power bank the website says it is 148 watt-hours (https://www.romosspower
That puts this bank at 40,000 mAh at 3.7 volts
(148) x (1,000/3.7) = 40,000
If you want to find the mAh rating for 5 volts it would be:
(148) x (1,000/5) = 29,600
Looking at an Anker product, for example Anker 525 Power Bank, they advertise the same way: 20,000 mAh
That looks like at 3.6 volts because the rated watt-hours is 72 according to the manual.
for 5v it would be 14,400 mAh
Someone please correct me if I've done something wrong.
You would have to measure one of these power banks and see if the rated watt-hours is correct. I don't have this Romoss product, but I do have the PHP30 Pro model sold as 111 watt-hours. It's pretty close to that from my testing. Reviews mention these things sometimes swell up. Mine hasn't yet and has worked well so far.
Last time I ordered this - it was super light, had rattling stuff inside, and definitely did not match the capacity by a long shot.
but people will get downvote us for ruining the party - so carry on.