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  #1  
Old 01-06-2008, 11:00 AM
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Andreas Andreas is offline
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Default Charging lithium-ion batteries

Consumers, store clerks, and manufacturers themselves have a lot of problem seperating facts from rumours when it comes to batteries. Here's the real deal on how to treat lithium-ion batteries (check your player's battery to see if its lithium-ion).

First charge
The first charge isn't any different from the 2nd, third, or 74th charge with lithium-ions. These batteries have built in circuits to automatically turn charging on and off, so there is no point in doing all the normal rithuals with charging it before using it, charging it for XX hours etc etc. If you have a lithium-ion, you're clear, no matter what the manual says. The XX hour first charge myth is left over from times with other battery types, and isn't relevant.
It should be noted however, that letting the device charge before you use it does allow you time to actually READ THE INSTRUCTIONS before you end up doing something you'll regret

Fully disharge/charge
Another myth, and a bad one. The only purpose ever in discharging a lithium-ion battery is to reset it's timer, so to display a more correct estimate for remaining battery time. Other than that, discharging your battery completely before recharging actually hurts the battery, as it's not designed to do so. Lithium-ions have a optimal life span when charged to about 3.92V, while 4.2V is max - and not recommended for extended periods of time. Also, charging a battery from 0% to 70% takes less time than to charge it from 70% to 100%, due to the charge method of such batteries.

Bottom line is that you should charge your battery often, and not max it out each time. It's better to charge it almost full many times than to fully charge it one time, in fact it might seriousely increase the life span of the battery if you charge it randomly.

Last edited by Andreas; 12-22-2008 at 04:08 PM.
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  #2  
Old 01-06-2008, 04:15 PM
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dfkt dfkt is offline
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If your player doesn't run on regular AA or AAA batteries, the chances are very high it uses a Li-Ion or Li-Poly battery.

As a rule of thumb: don't let a Li-Ion battery run dry all the time, top it off regularly. Only every 30th charge cycle (or once a month, whatever comes first) let it run dry, then fully charge again. This recalibrates the internal charging circuitry and gives a more precise reading on the player's battery gauge.

More info about various battery types can be found here: http://www.batteryuniversity.com/

(The disinformation about always fully discharging batteries originates from ancient NiCD batteries - a type of battery that hasn't been sold for more than ten years. What was considered good charging practice for these types of batteries is actually harmful for modern Li-Ion batteries.)
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Old 01-06-2008, 04:20 PM
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Are Li-polymer batteries any different? The D2 uses a Li-Ion anyway... IIRC.
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Old 01-06-2008, 04:23 PM
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The same should apply for all types of Lithium-based batteries: http://www.batteryuniversity.com/parttwo-34.htm
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  #5  
Old 01-20-2008, 09:09 PM
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Default The care and feeding of lithium-ion batteries

First, a little nit-picking: A "battery" is a collection of "cells" acting as one power source. A single, individual, discrete electro-chemical power source is called a "cell". Thus, a "AA battery" is actually a cell, and "packs of batteries" is actually just a "battery". A battery can consist of a single cell, but a single cell is never a battery. Also, "lithium" is an element and not a proper noun. The word should never be capitalized as a proper noun, only when at the start of a sentence or as part of an acronym or abbreviation.

Lithium polymer (LiPo) batteries are increasingly common in portable things smaller than laptops. As a specific type of lithium battery, all that generally applies to lithium-ion cells applies to LiPo cells.

A few items that could confuse a newcomer to the world of lithium batteries.

Storage:
Lithium batteries should be stored in a charged state. Over time they will slowly "leak" some of that charge (entropy at work), so for long periods of storage (many months without use, that is) it is a good idea to top off a lithium battery by charging it every so often. Because they are stored in a charged state, in most cases a brand new lithium-ion will be ready for use straight out of the package.

First Charge:
Though most batteries will come nearly fully charged, not all will. For example, some lithium electric drill batteries are sold fully-discharged (charging them the first time initiates a clock for warranty purposes, so that regardless of when bought, the battery is covered from the day it was first used). If your battery is not charged, do not immediately assume that it is defective. Charge it until the charger reports that it is fully charged. It may take minutes, or it may take the time of an entire charge cycle.

Normal Charging:
Every charging device for lithium batteries has a high voltage cutoff. When the battery reaches this voltage (usually ~4.2v), it is deemed fully charged, and the charger stops supplying current to the battery. Overcharging a lithium battery leads to permanent damage and can result in explosion and fire. Thankfully, all modern, quality lithium chargers prevent this from happening. This also means that it doesn't matter how long you charge a battery after the charger deems it full: the battery won't get any more fully charged, and you really don't want it to!

Discharging:
In general, lithium batteries are forgiving of varied discharging habits. Lithium batteries suffer from no "memory effect", and should thus be Except for the rare reason of recalibrating the battery capacity gauge mentioned above, there is no reason to deeply discharge a lithium battery outside of normal use. In some cases, "deep" discharges can be very harmful for batteries. A normal full cycle drains a lithium battery from its charged state of ~4.2v to a low-voltage cutoff (LVC) of usually ~3.0v. After this level the battery certainly still contains energy, however discharging below this level can (and if low enough, certainly will) cause permanent damage to the cell, including complete death of the cell. In many cases, a charger will not even attempt to charge a battery below 2.7v.

Charging:
It is better to charge a lithium battery whenever possible than to wait to charge the battery until it is fully drained. When charging the battery, let it charge to full capacity (or, at least, when possible). As long as the battery's charging circutry is undamaged, there is no harm in fully charging the battery. Besides, why wouldn't you want to have your PMP's battery full every time you go out?

Balancing:
Cell balancing comes up often with lithium batteries, and it is a very important part of the care of multi-cell batteries. However, nearly all PMPs use single-cell batteries, and devices that use multi-cell batteries use them is parallel configuration, which does not require balancing. Unless you are building a custom battery pack (in which case you will need to know a lot more than the scope of this guide), you will never need to fear your battery being "unbalanced".
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Old 01-09-2009, 02:36 AM
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I'll add a few things here and there, if that's OK.

When it comes to the 30th cycle, it is best to read the manual on if it is needed. Many PMP devices that simply rely on voltages do not need to be drained because it lacks the fuel gauge systems more advanced packs do. Also some computers (like Lenovo ThinkPads and some HP models) have special programs that calibrate batteries for you and best to use them. My laptop only requires a drain to around 3% on a monthly basis and lacks said calibration programs.

Topping off Lithium Ion based batteries is not recommended if it recently charged in the last few minutes or above ~95%. Some devices prevent this, but some do not. While most modern batteries do have overcharge protection circuits, charging above this level could force more charge into a battery than what it really needs. Also, leaving any chemistry battery plugged into for a prolong period of time, usually more than a day or two, is probably not good for them.

Lithium Ion packs that are multiples of 3.6V (7.2V is 2, 4 or 6 cell, 10.8V is 3, 6, or 9 cell, and 14.4V is usually 8, or 12 cell) are subject to cell balancing. The most obvious is the known symptom of a Lithium Ion pack instantly failing when one cell breaks its safety circuit rending that series unusable or critically weak. I do have a camcorder that one cell has failed, and only gives me 1 to 15 minute battery depending on how much current I draw from it.
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  #7  
Old 07-23-2009, 04:38 AM
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If you're going to nit-pick, watch out that you don't contradict yourself!

Quote:
Originally Posted by Muffinwalker View Post
First, a little nit-picking: A "battery" is a collection of "cells" acting as one power source. A single, individual, discrete electro-chemical power source is called a "cell". Thus, a "AA battery" is actually a cell, and "packs of batteries" is actually just a "battery". A battery can consist of a single cell, but a single cell is never a battery.
Quote:
Originally Posted by Muffinwalker View Post
Balancing:
Cell balancing comes up often with lithium batteries, and it is a very important part of the care of multi-cell batteries. However, nearly all PMPs use single-cell batteries, and devices that use multi-cell batteries use them is parallel configuration, which does not require balancing.
Whoops!
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  #8  
Old 07-26-2009, 06:48 PM
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Not that this is helpful to the purpose of the thread, but it wasn't a contradiction.

He was making the distinction between the terms "cell" and "battery." In official parlance, they mean different things, though occasionally (as is the case with single cell batteries) they are often used synonymously. A battery is a term given to a combination of cells between one and infinity used to store and discharge energy. In the case of single cell batteries, when you are referring to the cell, you never refer to it as a cell, rather as a battery. Therefore, when speaking about batteries, you will never have a single cell because you are either: A) Speaking of a single cell in arrangement with others that together form a battery; or B) Speaking of a single cell that acts on its own and therefore is referred to as a battery. Thus, a single cell is never a battery.

Sorry.
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