sinmarket
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Dear all
I would like to share some testing that I have done with power bank.
I believe there are a lot of miss-interpretation for Power Bank.
I have googled around the best DIY test available and decided to adapt using 2 x 10 Ohm resistor to get close to 5V and 1A output.
Powerbanks are rated in mAh (milliamp hours), just like the battery in your cell phone. They have about 70% to 80% efficiency; the rest of the energy is lost to heat. This means, for instance, that a 2600 mAh powerbank wouldn't completely fill your S4's 2600 mAh battery.
Most manufacturer will indicate the battery capacity used in the Powerbank as this will denote the highest capacity but please note that user is not able to use all this capacity.
Most of the powerbank is using lithium ion/polymer battery, voltage is 3.7V, after fully charge is 4.2V.
When you are using it to charge mobile devices, its output voltage need to be at 5V.
This mean that the 3.7V should be converted into 5V before it can charge your mobile device/
An example, for 10,00mAh powerbank,
3.7V x 10,000mAh = 37.00Wh = 5V 7,400mAh
So we are more concern on 5V output, that is 7,400 mAh
The conversion is not 100%, there will be some losses about 10% or more.
just take 10% as losses, so we have 7,400 x 90% = 6,660 @ 5V
if your handphone battery is 1600mAh capacity, it mean that it can charge your handphone for about 4 times.
what i tested here, i am measuring using power and not mAh, which is accurate. As you know, V x I= Power, Under 5ohm load, 4.97VX0.93A=4.6221Wh
Total discharging time is 6 hours 10 minutes.
From the chart below i can get a total power dissipation of 28.47 Watthour,
The rated power is 37Wh ( 3.7V x 10,000mAh)
28.47/37.00x100%=77% is the real capacity that can be used the rest is loss to conversion and heat.
I would like to share some testing that I have done with power bank.
I believe there are a lot of miss-interpretation for Power Bank.
I have googled around the best DIY test available and decided to adapt using 2 x 10 Ohm resistor to get close to 5V and 1A output.
Powerbanks are rated in mAh (milliamp hours), just like the battery in your cell phone. They have about 70% to 80% efficiency; the rest of the energy is lost to heat. This means, for instance, that a 2600 mAh powerbank wouldn't completely fill your S4's 2600 mAh battery.
Most manufacturer will indicate the battery capacity used in the Powerbank as this will denote the highest capacity but please note that user is not able to use all this capacity.
Most of the powerbank is using lithium ion/polymer battery, voltage is 3.7V, after fully charge is 4.2V.
When you are using it to charge mobile devices, its output voltage need to be at 5V.
This mean that the 3.7V should be converted into 5V before it can charge your mobile device/
An example, for 10,00mAh powerbank,
3.7V x 10,000mAh = 37.00Wh = 5V 7,400mAh
So we are more concern on 5V output, that is 7,400 mAh
The conversion is not 100%, there will be some losses about 10% or more.
just take 10% as losses, so we have 7,400 x 90% = 6,660 @ 5V
if your handphone battery is 1600mAh capacity, it mean that it can charge your handphone for about 4 times.
what i tested here, i am measuring using power and not mAh, which is accurate. As you know, V x I= Power, Under 5ohm load, 4.97VX0.93A=4.6221Wh
Total discharging time is 6 hours 10 minutes.
From the chart below i can get a total power dissipation of 28.47 Watthour,
The rated power is 37Wh ( 3.7V x 10,000mAh)
28.47/37.00x100%=77% is the real capacity that can be used the rest is loss to conversion and heat.
