It doesn't take 24 hours!

[Exaspera]

Batteries are my arch nemesis. With all the laptops and cell phones I supply for our employees. I have to explain all this crap over and over again to the same people.

Lithium-Ion Batteries come Charged, Ni-cads do not.

Ni-cads get what is know as 'memory', it has to do with the magnetic alignment of the molecules in the cell. Draining as much power out of the battery as possible then charging it back up generally removes the effect. This is also why you need to fully charge a Ni-cad before you use it.

All batteries HATE heat. Heating excites the molecules and the resistance drops. No resistance means the energy stored in the Battery is released as more heat. This is why leaving your cellphone in the car WILL on a hot day will drain it.

Lithium-Ion really sucks as a battery. They are dangerous, have heat issues and a short active life. Your going to get 3-5 years out if it. An uncharged lithium-Ion battery will become unusable in about 2 months time. Thats right uncharged. So when you leave your cell phone battery dead overnight couple nights a week you are hasting its demise. Oh yea Li-Ion also have cold. DO NOT PUT THEM IN THE FREEZER.

Yes it can take forever to charge a cell phone using a USB port. Not all USB ports are created alike. Some simply do not have the watts to charge the phone quickly.

Good info, thanks!

So what is the average camera battery? And is it good to let them drain all of the way down before recharging them? Is this question too general?

[Daskinor]

Most small electronics use lithium batteries because they are very light and have good constant voltage until they hit about 3-5% charge.

Lithium-Ion Batteries do not need to be totally drained before recharging them. that is a condition unique to nickel-metal hydride and nickel-cadmium. And even then it does not need to be done often. Only when the max charge time has dropped noticeably.

Camera batteries are generally very expensive because of two reason. Most company have unique batteries made for one model of camera. And two, most people forget to recharge the camera before storing it. A dead lithium battery in storage will become useless in 2-3 months.

[Captain Trips]

As to professors, they are like scientists: they study more and more about less and less, until they know absolutely everything about nothing at all!

And it is impossible to give an exact-to-the-second charge time, as no two batteries are identical due to manufacturing differences. One may have a few more milligrams of electrolyte than another, making it take a few more minutes to charge, etc. What this douchebag asked for was totally unreasonable -- which, if he were a professor of electronics production he would know, otherwise he's an idiot outside of his field.