Dont over charge #damaru

What will happen if a phone battery is overcharged? "overcharging" refers to, but I'll assume you mean leaving the battery on the charger all day, every day. Whether or not this is bad often depends on the cathode material in the battery. Most people don't know that in a lithium ion secondary battery, it's not the lithium that undergoes redox to provide electrons to power your device. It's one (or more) first-row transition metals (cobalt, nickel, manganese, iron, etc) secured in an oxide or phosphate crystal. Depending on which metal it is, the voltage of the charged battery could be 3.7 volts or as high as 4.5 volts. Now take a look at this chart: (source: Page on Lbl) Lithium ion batteries require an electrolyte which is a solvent that will dissolve a lithium salt. This will allow lithium salt to diffuse back and forth between the cathode and the anode to maintain charge balance whether all of the (mobile) electrons are in the anode (charged) or cathode (discharged). If you have a typical modern cell phone with a typical Lithium Cobalt Oxide (LiCoO2 or LCO) you can see that at the most-charged condition, which is left-most on this plot, the LiCoO2 cathode material is at about 4.35 volts, which is just above the oxidative stability voltage for the electrolyte in the battery. Some manufacturers will program their device to stop charging once the battery reaches 4.2 or 4.25 volts to increase the life of the battery, but the capacity will be reduced, so it must be advertised as having "6 hour life" instead of "7 hour life". It is a trade off. Since you don't really have any way of knowing what voltage your phone or computer was programmed to charge to, you can attempt to avoid a totally-charged state by stopping the charge at 80% or 90% to ensure you don't reach the point of oxidative instability. Also, it is best not to leave the battery on the charger all day and all night because a cheap charger will continue to trickle current into the battery, but once all the transition metals are oxidized, the electrolyte or other organic components may begin to oxidize, hurting the battery life. Expensive chargers will halt the current at a preset voltage. It is usually not possible to tell which you have in your device.