[Editor's Note]: The original author of this article is a member of the Scientific Squirrel Society , first published on his blog, the original title is:《 》

Yesterday, a report that "the battery of mobile phone is not durable or the SIM card is making trouble" spread wildly on the forum and microblog, saying that the power consumption of the old SIM that has been used for more than two years is 10 times that of the new one, which means that the mobile phone that was charged once a day can only stand by for 2 hours. However, few people refute such an absurd statement, and many netizens said they would pay to replace the card. It is reported that someone has measured the standby power of the old SIM card by using the mobile phone power monitoring software as high as 0.2~0.3 watts, which is obviously impossible. The peak power of GSM mobile phones can be up to 2W, which is transmitted in about 1/8 of the time interval. The maximum average power is no more than 0.25W, and this maximum average power will rapidly decrease after starting up and communicating with the base station. The standby power is much lower, about 0.02W. The mobile phone power monitoring software monitors the voltage value, and its power calculation is very inaccurate, and it will become more and more inaccurate as the battery ages.

In order to break the rumor, I guided students to test the standby power of new and old SIMs this afternoon. The test schematic is as follows:                 

The battery must be separated from the mobile phone so that the series ammeter can measure the power supply current, the parallel oscilloscope can measure the power supply voltage, and the multimeter can measure the voltage. The oscilloscope is used to observe the waveform of the power supply current at the same time. According to the voltage and current values, the actual power consumption can be calculated.

Take the battery out of the mobile phone, and solder the terminals on the positive and negative contacts for easy connection. The battery voltage is 4.18V, which can be used for normal operation of the mobile phone.              

I found two old and new SIM cards. The old one is Globelink, which has been used for 10 years. The new one is Shenzhouxing, which is a student's mobile phone. The mobile phone used for testing is my current HTC G7.            

Connect them according to the above test schematic diagram, and put new and old SIMs into them for comparative test. It is found that the current will have a peak value of 1-2 seconds when starting up, then it will drop rapidly, and the power supply voltage will remain unchanged. The standby current of both cards is several milliamperes to 10 milliamperes, and it is about tens to more than 100 milliamperes when making a phone call. There is no obvious difference.              

The original said that the voltage of the new and old SIM cards is different, not to mention that voltage and power are not the same thing. Anyone who knows a little about electronics knows that this chip used for identification is micro power, and its weight is like sesame on a pancake for the power consumption of the entire mobile phone. In fact, the most power consuming part of smart phones is the screen.

Like me, the microblog controller who can easily open the screen to brush microblog, the battery of the mobile phone is changed once a day, or even twice a day. The performance of lithium battery will decline after being used for a long time, which is the main reason why the standby time of mobile phone is getting shorter and shorter. I have no choice but to buy a few more batteries. I have five batteries, two seat chargers and a charging bank.            

In the original text, the claim that the plastic on the SIM affects the magnetization is groundless. The aging of the SIM card leads to the increase of the contact resistance and a large amount of power consumption, which even leads to frequent registration with the base station. If you persist in worrying about this problem, you don't need to spend money to replace the SIM card. Just find a rubber to wipe the SIM card.

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