Why does the charge change in different power sources?

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Dim Boy2020-04-25 11:55:49

Batteries

Dim Boy, 2020-04-25 11:55:49

A strange thing: I charge the phone from charging - the voltage strength through the tester is 1.8A , I
connect the phone to the Power bank 0.55A, instead of the phone I connect the load, the power bank gives out + -2 A, the situation is similar on the second power bank.

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3 answer(s)

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Sergey Pankov, 2020-04-25
@twix007

voltage strength through the tester 1.8A

Wow, how messed up.

U - voltage, measured in volts.
I - current (current strength) in amperes.
P - power - this is the amount of energy transmitted / received / consumed per unit of time: it is equal to the product of voltage and current: P \u003d U * I. Measured in Watts.
W - the amount of energy (or in other words - work) is measured in Kilowatt * hour (if we are talking about your home meter), or Watts times seconds (W * s) - this is Joules (J).

Now what do you have. The current can be large, but the voltage could sag when a resistive load is connected to the power bank. Perhaps a bad cable also added a voltage drop and lowered it at the input to the phone.
Dumb resistive load - it doesn't care, it just heats up. The power bank is trying to hold a current of two amperes, but there is not enough power and the voltage sags below 5 volts. A resistive load doesn't care, but the phone cares. A low voltage is not suitable for him, since a low voltage cannot charge the battery without an increase.
The power is limited, and where this power will be converted (into a greater current or into a greater voltage) depends on how the power source is arranged.
Please note that the voltage tester shows you when you take two amperes from the power bank with a resistive load. Maybe this is not enough for the phone and it reduces the current (increases, roughly speaking, its resistance) so that
the power bank has enough power to provide the desired voltage.

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6yntar05, 2020-04-25
@6yntar05

Maybe PowerBank does not produce too much current? As I understood from your question, PowerBank gives out 0.5 Amperes maximum? This is the current strength of a conventional USB connector, this is the norm.

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anikavoi, 2020-04-25
@anikavoi

Forgive the illiterate, but doesn't the current strength directly depend on the load resistance?
Force = Voltage / Resistance - Ohm's law.
If the load resistance is different, and the voltage is the same, then the force should be the greater the lower the load resistance.
Or not?