Why battery is bulging?!

          Battery Charging

  Some people say that the battery bulges due to charging the mobile overnight but a question raises when we realize that the overnight charging actually won’t affect the mobile battery life much.


Let's see the reason behind the battery bulging.

            If u wanna check out why the battery is getting bulged you may try with any of your old devices by plugging it into the wall socket and keep the supply ON for several days..the result will be:you won’t find any difference in the battery shape if u do charge for a few days.


            This is because the battery charging circuits include a Battery Management System(BMS) which prevents overcharging and low voltage problems.

The battery won't get bulge even if you supply power with a 9v rated charger, again it's because of that BMS which always keeps an eye on the battery health/input current and voltage.

            Generally, most of the mobile batteries(Li-ion) are rated with 4.2 input volts..when we try to give a high voltage the BMS takes care of that problem.

            Even though the BMS controls the flow it is only up to a certain limit if the limit exceeds the consequence may be very bad(battery may explode).

            To really do an experiment with the battery we need to remove the battery management system(BMS) from the battery charging circuit and directly connect the battery input terminals to the supply of 5v or greater.

CAUTION: If you do the above-said experiment it may even explode so be cautious. For instance, if you are testing the battery like this for a more hours/beyond a whole night you might find the battery bulged.{alertWarning}


Battery working - Basics

            Basically, a battery consists of two terminals (mobile battery may have 3 terminals for the BMS connection as well) 

A Battery’s two terminals are :

  • Anode
  • Cathode


  1. ANODE: it's the terminal/electrode which has the tendency to LOSE an electron.
  2. CATHODE: it's the terminal/electrode which has the tendency to GAIN an electron.


            In-between the two terminals there will be an electrolyte which is a semi-permeable thing.

It is present to prevent the direct movement of electrons from the anode to the cathode.

            Once the anode and cathode terminals are connected across a circuit/component terminals the circuit is powered and starts working!!!...its a simple electrical fact that the current flows in a closed circuit.


            If the electron gets into the cathode directly from the anode terminal the battery will be blasted off!!...oops..



            Soon after the battery is discharged it has to be recharged for the next usage cycle..the process gets reversed ie: the electrons move from the cathode to the anode terminal via the charging circuit when a charger/adapter is connected and powered.



            For a better battery life put your mobile on charge when it reaches about 30-40% of battery capacity don’t let the percent fall below 30% as the ions may get stuck in the permeable membrane while recharging..it may happen due to aging and dry electrolyte.


            Hope this helps!! Let us know your thoughts in the comment box..

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