The first 10%...

[JayS3]

of battery, Seems to deplete the fastest, And takes ages to charge up to full again! EG my batter could be like 45% and I'll stick it on charge, Half an hour later itl be on the higher 80s normally. But I'll have it fully charged, Take it off charge and lightly use it for about 5 mins and its on like 92% which then takes aaaages to get back to 100.. Wierd huh.. The actual life is good after the 90, I'd come back after 9 hours at work with mild to heavy usage and it'l be on like 70%ish.. That first 10% sucks! Especcially with someone like me who has to leave the house with 100% battery Been told I have a mild OCD!! Anyone else notice this?

 

[Fille84]

Yep, noticed that too..

 

[Evo 5oh]

Mine is about 30% or less goes down pretty quick but man this phone last forever

 

[ardyer]

I'm not an expert on Lithium-Ion of batteries, but here is my understanding of how they work.

The 90-100% range is pretty inaccurate. Most of these batteries almost never actually reach 100% charge, so the OS compensates by saying it is 100% when it is just "as full as it seems it will get." Therefore, the first 10% or so drains the fastest because it wasn't all there to begin with.

Then the way they are charged makes this the slowest to come back as well. For the first X percent (not sure what the number is, but it is enough to make it usable for awhile) the charger uses a fast charge that is less efficient. Then the remaining is trickle charged, which is more efficient but slower.

So all this to say that what you are seeing may just be the way that Lithium-Ion batteries work.

 

[jerofld]

The reason why the 90%-100% charging is so slow is because Li-Ion batteries charge like how most people eat. When you're hungry, you tend to eat fast. As you get full, you slow down. When you're near full, you end up chewing more and taking longer pauses between bites, etc. A Li-Ion battery is the same. The more depleted it is, the faster it can charge, because there is more 'room' for it to charge. As it gets around the 90% mark, there is less 'room' to charge (it's really a chemical that holds the voltage, so there is less that is not charged) so less current is applied to the battery to charge.

As for the first 10% depleting faster, it's due to in part to the Android battery display algorithm and partially because Li-Ion batteries deplete quickly on the extreme ends of charge (the first 10% and the last 10%). The last 10% is less noticeable because Android kicks in battery saving measures to extend the last 10% as long as possible.