Something about portable batteries
Hello, dear friends! Choosing a portable battery, you can encounter a large number of negative reviews about the discrepancy between their declared capacity and the number of charged gadgets. It would seem that by buying a 13,000 mAh charge, we need to charge our smartphone with a 2300 mAh battery about 5.5 times! But not everything is so simple.
As a lover of gadgets and modern technologies, I have a smartphone and other good things. And on a certain path I encountered one, in my opinion, a serious problem of advanced devices - they have a relatively short battery life. Yes, I will not argue, there are “monsters” of the telephone industry, with 4000 mAh or more batteries. But, often, such devices are extremely rare and have other drawbacks. In any case, even if your gadget can hold out until the evening (and my Nexus 5 c 2300 mAh is not from this list), sooner or later the question arises of buying a portable battery.
Like many geeks, my hands have long been itching to purchase this type of device. I also considered the options for buying boxing for 18650 batteries, as well as for a ready-made device (in which, with a huge amount of probability, those 18650 stand, as well as in laptop batteries). As a result, there was a need to have a charged phone at work in the absence of an outlet, and a portable battery DF TRIO-02 was purchased.
Frankly, there was not much time to choose and read reviews. Just quickly “went through” one well-known online store(the one that is in the group of companies along with the bank and the jeweler) and was selected according to the following criteria:
Pros:
Minuses:
For ease of calculation we introduce the following assumptions :
To eliminate inaccuracies let's look at Wikipedia :
On the package we have a proud inscription: "13000 mAh." This is our charging capacity.
Carefully looking at the sticker on the reverse side we see the following.
Voltage: 3.7 V.
Charging capacity: 13000 mAh.
Energy capacity: 48.1 Wh.
It turns out that many manufacturers indicate the stored charge in mAh (mAh), but the voltage of this device is also important. To the fullest extent, “capacity” is characterized by stored energy .
Often people confuse the concept of stored charge and stored energy calling it “capacity”. If high accuracy is not needed, then we can assume that the stored energy (in Wh) is approximately equal to the product of the stored charge (in Ah) by the average voltage (in Volts).
1 W · h = 1 V · 1 A · h
Now, having understood the concepts, let's move on to our example: 48.1 The battery is 13 Ah (13000 mAh) multiplied by 3.7 V. So far, everything converges. But, our device is charged from the output of 5 V. Therefore, the charge that our device is capable of issuing is located as a quotient from the stored energy and output voltage.
48.1 Wh / 5 V = 9.62 Ah (9620 mAh).
Now you can easily count "how many times I can charge my device." So, the same Nexus 5 can be charged:
9620 mAh / 2300 mAh = 4.18
Or, in other words, a little more than 4 times . What vs 5.5
The calculated reserve charge of 9620 mAh was 26% less than the 13000 mAh that we see on the box. And 26% less than an inexperienced user expects. Although, in fact, the manufacturer did not deceive us at all. Just such a marketing ploy.
Useful articles and sources:
» Electrical Capacity
» Electric battery
» Ampere hour
A bit of background
As a lover of gadgets and modern technologies, I have a smartphone and other good things. And on a certain path I encountered one, in my opinion, a serious problem of advanced devices - they have a relatively short battery life. Yes, I will not argue, there are “monsters” of the telephone industry, with 4000 mAh or more batteries. But, often, such devices are extremely rare and have other drawbacks. In any case, even if your gadget can hold out until the evening (and my Nexus 5 c 2300 mAh is not from this list), sooner or later the question arises of buying a portable battery.
Like many geeks, my hands have long been itching to purchase this type of device. I also considered the options for buying boxing for 18650 batteries, as well as for a ready-made device (in which, with a huge amount of probability, those 18650 stand, as well as in laptop batteries). As a result, there was a need to have a charged phone at work in the absence of an outlet, and a portable battery DF TRIO-02 was purchased.
Frankly, there was not much time to choose and read reviews. Just quickly “went through” one well-known online store
- required capacity
- price quality
- appearance (yes, you need to strive not only for ergonomics, but to enjoy aesthetically)
Briefly about this very device
Pros:
- good capacity
- two exits on 5B, 1 A; one exit 5B, 2.1 A
- microUSB battery charge input
Minuses:
- Marky glossy case
Capacity calculation arithmetic
For ease of calculation we introduce the following assumptions :
- take the efficiency of the voltage converter for 100%
- we take all the indicated capacities for real values
- we consider constant values ​​of current and voltage during charging
- charging the phone comes from the ideal 0% to 100% (without taking into account the residual charge that manufacturers put, etc.)
To eliminate inaccuracies let's look at Wikipedia :
The maximum possible battery charge is called the charging capacity, or simply capacity. Battery capacity is the charge given by a fully charged battery when discharged to the lowest allowable voltage. In the SI system, battery capacity is measured in pendants; in practice, an off-system unit is often used - ampere hour. 1 Ah = 3600 Cl. Battery capacity is indicated by the manufacturer. Not to be confused with the capacitor electrical capacity.
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Nowadays, energy capacity is indicated more and more often on batteries - energy given by a fully charged battery when discharged to the lowest allowable voltage. In the SI system, it is measured in joules; in practice, a non-system unit is used - watt-hour. 1 TW = 3600 J.
On the package we have a proud inscription: "13000 mAh." This is our charging capacity.
Carefully looking at the sticker on the reverse side we see the following.
Voltage: 3.7 V.
Charging capacity: 13000 mAh.
Energy capacity: 48.1 Wh.
It turns out that many manufacturers indicate the stored charge in mAh (mAh), but the voltage of this device is also important. To the fullest extent, “capacity” is characterized by stored energy .
Often people confuse the concept of stored charge and stored energy calling it “capacity”. If high accuracy is not needed, then we can assume that the stored energy (in Wh) is approximately equal to the product of the stored charge (in Ah) by the average voltage (in Volts).
1 W · h = 1 V · 1 A · h
Now, having understood the concepts, let's move on to our example: 48.1 The battery is 13 Ah (13000 mAh) multiplied by 3.7 V. So far, everything converges. But, our device is charged from the output of 5 V. Therefore, the charge that our device is capable of issuing is located as a quotient from the stored energy and output voltage.
48.1 Wh / 5 V = 9.62 Ah (9620 mAh).
We analyze
Now you can easily count "how many times I can charge my device." So, the same Nexus 5 can be charged:
9620 mAh / 2300 mAh = 4.18
Or, in other words, a little more than 4 times . What vs 5.5
Draw conclusions
The calculated reserve charge of 9620 mAh was 26% less than the 13000 mAh that we see on the box. And 26% less than an inexperienced user expects. Although, in fact, the manufacturer did not deceive us at all. Just such a marketing ploy.
Useful articles and sources:
» Electrical Capacity
» Electric battery
» Ampere hour
Source: https://habr.com/ru/post/364385/
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