[Samsung Galaxy Nexus] kam187:
Yeah that's true. The optimal point to charge at is 30%, and optimal storage is about 70%. Thats why when you receive your new phone its usually at about 60 to 70%. You can probably tell how long its been on the shelf by how much lower than 70% it is!

At the one extreme the cells can get plated, and at the other they deteriorate due to a chemical reaction and heat, which is why overcharging can cause heat, explosion and fire.

Having said that, charging circuits in phones are smart, and won't overcharge the battery too much. They have a trade off between trickle charging while the charger is in to make sure when you disconnect you're still at 100%, and not constantly charging the battery. Since you're not really 'storing' the battery at 100% and you're going to be using it once charged its not really an issue with phones.

Laptops are a different story. The tradeoff fails because over weeks/months the laptop is constantly trickle charging back to 100%. This is why some power managers like on Thinkpads give you the option to extend battery life by sotring at a more optimal temperature, and also letting the battery drain naturally by not constantly charging it.

With regards to the battery minimum, you'll notice most phones switch off at about 5% - or if they say 0% its actually in reality about 5 %. This protects the battery. If you were to go on holiday or something and leave your phone at home, it would probably be very bad if you left the battery at 0% or on the charger. But since in normal situations you'll charge it again pretty quickly (lets even say within 2 days) its really not an issue as it won't hit true 0% by then.

I was trying not to overcomplicate things, as some people have too much battery OCD as it is lol. In my opinion the benefit to the battery of only charging to ~70% and/or recharging at 30% is outweighed by the 30% you're losing on either end. You're battery will need some abuse to lose 30%, so no need to be OCD about these 30/70 levels. (I know that's not what you're implying)

What is definitely bad tho, is constantly plugging it into a charger all day long. However, again the extra charge may outweigh any battery deterioration in your personal situation. For example if i worked in an office where i had a dock, and was constantly in and out for hours at a time, i'd stick it in the dock without worrying about it. That would give me a better battery experience in real terms than not charging it all day and getting caught short while out of the office - for the sake of a few % battery deterioration.

Yeah those are fine. The range is because thats the operational range on the regulator it uses. Any charger probably varies by that much. +/-10% is a general safe limit.

Cheap chargers tho (like the cheap plug in the wall DIN plug ones with 1.5v, 3v, 4.5v etc) usually have no regulation circuit in them. Generally in that case reaction to draw is slow, and power output remains constant for a period of time. In this case power is the output from the transformer that converts 120 or 240VAC voltage to the DC voltage - and Power = Current * Voltage.

If the device suddenly draws more current or less current since power output can't react, Voltage changes. Imagine the current draw suddenly halved, the voltage would double for a short period and level back off to the correct voltage after power output from the charger reacted. If you have a volt meter try it one day with one of those chargers and the toy cars etc they come with.. measure the voltage across them then turn your toy on/off!

---------- Post added at 08:04 PM ---------- Previous post was at 07:58 PM ----------

Yep, using it as my second charger. Ironically it has a US plug and I hate the size of it with the adapter. Complete opposite problem of the OP :P