If you have recently bought or owned a powerbank before then you must have thought your powerbank is broken because it does not deliver the full capacity written on them. But thats not the case and heres why
Before starting the actual explanation let's make somethings clear. Lithium ion batteries, those used in your mobiles and powerbanks operate at 3.6V to 3.8V and the USB port and other circuits operate at 5V.
So, knowing this and assuming the powerbank is charged let's run a hypothetical charge.
Assuming you understood what's happening here and not going deep into it's working, some power (around 20-30%) is lost in the form of voltage conversions and heat. Moreover, batteries degrade over cycles and thus their charge holding capacity decreases, so an old 10,000 mah powerbank you own may only have 7,000mah capacity left now. It is recommended you buy a bigger capacity battery so you have to charge it less number of times. A typical Lithium ion battery has a life of about 1000 charge cycles.
If you want to check out the mathematics too then click here.
So, in conclusion, the power losses in voltage conversions, heat and reduced battery capacity are the reason why your powerbank doesn't deliver full capacity as promised.
It is recommended you buy branded powerbanks as their circuits are more efficient and hence deliver closer to the promised numbers and will have a better life.
Before starting the actual explanation let's make somethings clear. Lithium ion batteries, those used in your mobiles and powerbanks operate at 3.6V to 3.8V and the USB port and other circuits operate at 5V.
So, knowing this and assuming the powerbank is charged let's run a hypothetical charge.
- Once the powerbank is plugged in to your mobile, the electrons from the bank will start moving towards the mobile's battery. BUT, the USB port works at 5V and the battery can only provide a voltage of 3.6V to 3.8V, so the voltage is first converted to 5V.
- Then this 5V current flows through the wire and enters your mobile and goes through the circuits which operate at 5V so there's nothing to worry.
- Now it has reached to the battery and will charge it.
- But the battery can only accept current at 3.6V to 3.8V. So, the current again is converted to the acceptable voltage and then it finally charges your phone.
Assuming you understood what's happening here and not going deep into it's working, some power (around 20-30%) is lost in the form of voltage conversions and heat. Moreover, batteries degrade over cycles and thus their charge holding capacity decreases, so an old 10,000 mah powerbank you own may only have 7,000mah capacity left now. It is recommended you buy a bigger capacity battery so you have to charge it less number of times. A typical Lithium ion battery has a life of about 1000 charge cycles.
If you want to check out the mathematics too then click here.
So, in conclusion, the power losses in voltage conversions, heat and reduced battery capacity are the reason why your powerbank doesn't deliver full capacity as promised.
It is recommended you buy branded powerbanks as their circuits are more efficient and hence deliver closer to the promised numbers and will have a better life.
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