# What determines the current drawn by phone battery? Phone (load) or charger or both? [closed]

What actually determines the current drawn by phone battery? Is it the phone battery (load) or the charger (supply)?

For instance, the charger that came with my phone reads 1.5 A. Also, I have two more chargers available rated 1 A and 2 A. Which one of the two is safe to use with my phone? I have read several claims regarding the same:

Claim 1: Using a less amperage charger would overburden the charger as the current drawn is decided by the load (assuming the load to be resistive)

Claim 2: Using a higher amperage charger would charge the battery faster but at the cost of reduced battery life (implying that current drawn is decided by the charger and the load is capacitive and hence able to absorb any reasonable no of amperes)

My understanding: As I understand, the current should be decided by both the charger and the phone in line with the CCCV scheme.

My questions: Which of the claims is actually true and is my understanding correct? Which of the chargers is theoretically safe to use and what model is an actual representative of the battery (resistive vs capacitive)?

## closed as off-topic by Leon Heller, MCG, Dmitry Grigoryev, Voltage Spike, PeterJJun 29 '18 at 11:40

This question appears to be off-topic. The users who voted to close gave this specific reason:

• "Questions on the use of electronic devices are off-topic as this site is intended specifically for questions on electronics design." – Leon Heller, Dmitry Grigoryev, Voltage Spike, PeterJ
If this question can be reworded to fit the rules in the help center, please edit the question.

• I assume you haven't bothered doing any research? This question has been answered here a few times (on phone so can't be bothered to find one) and there is hundreds of articles online if you can use Google. It's the phone. The phone determines the current it needs. – MCG Jun 22 '18 at 18:22
• Let's think about this for a second: Why would you use a 1A rated charger on a phone that draws more than 1A? Do you know what the current rating on a charger is? – KingDuken Jun 22 '18 at 18:24
• @MCG I have seen a lot of answers on several sites but none seemed reliable. I have therefore asked this here for reliable answers from subject experts in battery charging. – Pikachu Jun 22 '18 at 18:25
• @MCG Can you tell why the phone would decide amps? If I think of battery as capacitor, it can take up any current. For instance, in an EV, the same battery (load) takes in different amps at different levels of charging – Pikachu Jun 22 '18 at 18:27
• @King Duken Why can't I? The battery won't die if fewer amps are provided. It would simply take more time to charge it. – Pikachu Jun 22 '18 at 18:29

The phone or any smart apparatus is responsible for safely charging it’s OWN battery.

The charger is responsible for supplying power and protecting itself from any overload.

The smart phone is also capable of detecting if the supply voltage is being overloaded and therefore reduces its demand to be in the useful range.

Therefore the current is limited by either of the supply or the demand , whichever is smaller.

In both cases each is responsible for protecting itself.

• +1 for providing a civil answer. – Curt Nichols Jun 22 '18 at 19:18
• I had summer jobs as a civil engineer in early 70’s but unlike many here, They may benefit as I did in anger management classes – Sunnyskyguy EE75 Jun 22 '18 at 19:49
• @CurtNichols True that. +1 for someone wanting to respond positively and encourage questions instead of (the ones in the comment box) 'announcing' that this question already has an answer! – Pikachu Jun 23 '18 at 4:23
• Just like power, words can charge and discharge an atmosphere here and each must be responsible for protecting themselves and not doing harm to others. Otherwise these are ancient barbaric unregulated ways. – Sunnyskyguy EE75 Jun 23 '18 at 13:00

There have been many answers to this type of question, but apparently the OP is not happy with them.

The phone has a charge control IC in it. Regardless of what the adapter/source is rated, the internal charger IC will maintain a safe charging level for the battery. The wall adapter/USB source/whatever input supply is NOT the charge controller nor does it directly charge the battery.

Most of these ICs can detect if the input voltage from the source starts to drop, and they will cut back on the charge current to maintain the maximum available charge to the battery given the capability of the source.

Lest this all be considered opinion without support, you can read about all the detailed operation of this type of IC in This datasheet. About the only way to cause damage would be to supply the phone with a voltage that is higher than the abs max rating of any of the internal components, charge IC included.