No need to turn screen brightness down?

[donaldekelly]

I have been turning down the brightness on my screen to conserve the battery. Not that it ever gets low - but with the thought of prolonging the battery.

Then I remembered reading that the Lithium polymer batteries actually do not go dead (unrechargeably dead) from use but rather from time. They last about a year and one half regardless of how much you use them. (I think the figure was a year and 1/2).

So, if this is true (I will look for link) and if you recharge at work and at home like I do - then there is no reason to turn down brightness, is there? (I don't wi-fi or do much movies or mp3 so to the extent that the battery gets very drained).

The article pointed out that you want to buy newly made batteries, not ones that have been discounted since they have been on the shelf for a while. I have read here that one can replace the battery oneself on clies.

Maybe not the profoundest thought - but I was curious. I like the bright screen - and now am thinking - why not?

[n2ifp]

People turn down the brightness to extend run time.

Typically you get 5 hours at minimum vs 2.5 hours at full brightness.

[T1000X]

Like n2ifp said, turning down the brightness increases the run time, not the lifespan. I know my NX70V won't last forever, but hopefully before the battery dies I will have upgraded already. In fact, that is what Sony is counting on that you will upgrade again in a year and a half to two years. Why else would they keep coming out with different models?

[sstrasser86]

but he is saying since he recharges so much it doesn't matter cuz it will still die sonner or later

[Puppy]

Lithium Ion battery lives depend on how much total current passes in and out of them. They certainlly have a longer shelf life than a year and a half!

So yeah, the less you use the battery, the longer it's going to last. Turning down the backlight WILL improve that. But personally I'd just use it however you want, and not worry about it.

[n2ifp]

Another reason that I keep the brightness down is to save on the backlight's lifespan. Yes, they can go bad over time, usually it's a long time, but why stress it. Same thing with my dash lights in my truck, I keep the brightness down and they'll last a lifetime.

[cepler]

Have you ever tried using your Clie at night in a car at 50%-100% brightness? You'll go blind! I turned mine on in the car at 50% and was a bit shocked. BLAMO! Was that a nuke that just went off?! PHEW!

[Wolfsmoke]

I hadn't turned the brightness down on mine and had been using a mostly black background. I switched to a mostly white background, then crawled into bed to read awhile. I turned the light off, turned my Clie on... my retinas did NOT thank me! Dang! Let's just say, 50% works fine for me, and I am seeing noticeably longer battery life between charges.

[archangel]

I have to have mine on the lowest brightness setting for comfort. Its a very bright screen.

[little_Goomba]

This brings up an interesting point.
A simple small phillips screwdriver to the screw below the Lock switch is all it takes to gain access to our batteries. In my case, I plan on actively using my NX for at least two more years before I consider upgrading. (I used my Handspring from the day it came in from web-preorder until last october.)
I also used to work for a battery company. It is true that pretty much regardless of use, your LiIon battery will degrade in capacitive performance (how long you can operate between charges) over time. Eventually, I will need to replace my battery. It is also true that LiIon batteries age while sitting in a shelf. So I dont want to buy the battery now.
Here is a concern: At the rate Sony introduces new models, will there be a replacement battery for my NX next year? The year after? I've not investigated where to buy replacement batteries, but think I will be doing so after this post.

[donaldekelly]

"10.5 How to Prolong Lithium-based Batteries

Today’s battery research is heavily focused on lithium chemistries, so much so that one could assume that all future batteries will be lithium systems. Lithium-based batteries offer many advantages over nickel and lead-based systems. Although maintenance free, no external service is known that can restore the battery’s performance once degraded.

In many respects, Li-ion provides a superior service to other chemistries, but its performance is limited to a defined lifespan. The Li-ion battery has a time clock that starts ticking as soon as the battery leaves the factory. The electrolyte slowly ‘eats up’ the positive plate and the electrolyte decays. This chemical change causes the internal resistance to increase. In time, the cell resistance raises to a point where the battery can no longer deliver the energy, although it may still be retained in the battery. Equipment requiring high current bursts is affected most by the increase of internal resistance.

Battery wear-down on lithium-based batteries is caused by two activities: actual usage or cycling, and aging. The wear-down effects by usage and aging apply to all batteries but this is more pronounced on lithium-based systems.

The Li-ion batteries prefer a shallow discharge. Partial discharges produce less wear than a full discharge and the capacity loss per cycle is reduced. A periodic full discharge is not required because the lithium-based battery has no memory. A full cycle constitutes a discharge to 3V/cell. When specifying the number of cycles a lithium-based battery can endure, manufacturers commonly use an 80 percent depth of discharge. This method resembles a reasonably accurate field simulation. It also achieves a higher cycle count than doing full discharges.

In addition to cycling, the battery ages even if not used. The amount of permanent capacity loss the battery suffers during storage is governed by the SoC and temperature. For best results, keep the battery cool. In addition, store the battery at a 40 percent charge level. Never fully charge or discharge the battery before storage. The 40 percent charge assures a stable condition even if self-discharge robs some of the battery’s energy. Most battery manufacturers store Li-ion batteries at 15°C (59°F) and at 40 percent charge.

Simple Guidelines

Charge the Li-ion often, except before a long storage. Avoid repeated deep discharges.
Keep the Li-ion battery cool. Prevent storage in a hot car. Never freeze a battery.
If your laptop is capable of running without a battery and fixed power is used most of the time, remove the battery and store it in a cool place.
Avoid purchasing spare Li-ion batteries for later use. Observe manufacturing date when purchasing. Do not buy old stock, even if sold at clearance prices.

http://www.technick.net/public/code/

(then go to "guides", "technology-batteries", then "10:5")

[stog75]

Damn...now thats some info! It important understand the mechanisms, principles, and driving forces behind the devices. Thanks donaldekelly!

Not to threadjack or anything, perhaps its been asked before but oblige me:

Is it better to shallow charge the Clie or wait till it gets a little low then fully charge,...with respect to battery life and efficiency?

[DanT]

I charged my N760C every day, at work and at home, whenever possible. It seldom gets below 60%, only during a long flight trips. Since then I have 4AA external battery adapter available. It's been 19 months now and it looks as if its battery can go for another year or so. By then I can go buy another battery.

The only thing I worry about is the frontlight lifetime. If that goes out, how do I replace it?  I turn the frontlight off but keep the Clie on while it is sitting on the cradle for all those months in order to keep the life span of the frontlight long.

[Puppy]

I've read from some sources that even with lithium batteries you should prep them by fully charging and discharging them 3 times before moving to normal use (ie, charging it whenever). Anyone know for sure if that's true?

[donaldekelly]

The site listed above tells of the difference in batteries. I think there are two or three different lithium batteries, so one kind may need that initial complete discharge and recharge. I believe the lithium polymer - which we have in our NX clies does not. But, check it out.

My source has disproved my contention - that one does not need to keep the screen brightness down. It says that use and drainage does shorten the life of the battery - just as puppy said.

The batteries will die with or without use after a while, but the more charged up you keep it and the less you use the battery - the longer they last.

[LeggNet]

Originally posted by little_Goomba
A simple small phillips screwdriver to the screw below the Lock switch is all it takes to gain access to our batteries.

Actually, it is a bit more complicated.....

http://www.cliebattery.com/up503759install.htm

.....but still easily changed.

Cheers, Rich

p.s. Larry, am I to understand that you said that if you turn off your dashboard lights on your truck then they'll last forever? Do you also use this principal with the headlights? :D

[donaldekelly]

More than you wanted to know:

4.6 Charging the Lithium Polymer Battery

The charge process of a Li-Polymer is similar to that of the Li-ion. Li-Polymer uses dry electrolyte and takes 3 to 5 hours to charge. Li-ion polymer with gelled electrolyte, on the other hand, is almost identical to that of Li-ion. In fact, the same charge algorithm can be applied. With most chargers, the user does not need to know whether the battery being charged is Li-ion or Li-ion polymer.

Almost all commercial batteries sold under the so-called ‘Polymer’ category are a variety of the Li-ion polymer using some sort of gelled electrolyte. A low-cost dry polymer battery operating at ambient temperatures is still some years away.

[Puppy]

Very interesting! Geez, I wish it had specifically addressed the issue of conditioning a li-ion battery when you're first using it though. From the article, you'd think you wouldn't have to (and it clearly says you SHOULDN'T when you're just using it normally)-but that dosen't nessisarily mean you don't need to still condition it initially...

I got that info from a site that sells batteries, and claimed that far all 3 types, initial conditioning (charge/discharge 3 full times) improves their life. Also, my most recent Nokia cell phone (which is only available with a Li-Ion) says the same thing...although it's always possible that's just a misprint, left over from NiCD and NiMH batteries. It would be SOOO cool if you don't have to worry about how you charge Lithium ones at ALL.

Another question maybe someone knows. With Li-Ion is it best to COMPLETLY recharge it if you're going to recharge it? Or is it okay to (for example) just plug something in for 10 minutes or whatever, even though it's not getting "topped off". I've always assumed that would damage a battery, but I don't think I've ever actually read anything that addresses that.

Of course, for something like a PDA it's pretty hard to worry about how you're charging the battery.

[donaldekelly]

The article - or one of the articles on teh site mentioned "memory" - needing to charge and recharge nicad batteries and to a lesser extent the NIMH batteries because the cell chemistry is not fully formed when the battery is produced. It did not mention much about lithium batteries in this regard. I wll try to copy it below.

Maybe this will be the info you are looking for - my mind is a little tired - so I am not going to try to figure out if it does today.

Reader beware! (More not necessarily needed info)

---------------------------------------------

10.1 Memory: myth or fact?

The word ‘memory’ was originally derived from ‘cyclic memory’, meaning that a NiCd battery can remember how much discharge was required on previous discharges. Improvements in battery technology have virtually eliminated this phenomenon. Tests performed at a Black & Decker lab, for example, showed that the effects of cyclic memory on the modern NiCd were so small that they could only be detected with sensitive instruments. After the same battery was discharged for different lengths of time, the cyclic memory phenomenon could no longer be noticed.

The problem with the nickel-based battery is not the cyclic memory but the effects of crystalline formation. There are other factors involved that cause degeneration of a battery. For clarity and simplicity, we use the word ‘memory’ to address capacity loss on nickel-based batteries that are reversible.

The active cadmium material of a NiCd battery is present in finely divided crystals. In a good cell, these crystals remain small, obtaining maximum surface area. When the memory phenomenon occurs, the crystals grow and drastically reduce the surface area. The result is a voltage depression, which leads to a loss of capacity. In advanced stages, the sharp edges of the crystals may grow through the separator, causing high self-discharge or an electrical short.

Another form of memory that occurs on some NiCd cells is the formation of an inter-metallic compound of nickel and cadmium, which ties up some of the needed cadmium and creates extra resistance in the cell. Reconditioning by deep discharge helps to break up this compound and reverses the capacity loss.

The memory phenomenon can be explained in layman’s terms as expressed by Duracell: “The voltage drop occurs because only a portion of the active materials in the cells is discharged and recharged during shallow or partial discharging. The active materials that have not been cycled change in physical characteristics and increase in resistance. Subsequent full discharge/charge cycling will restore the active materials to their original state.”

When NiMH was first introduced there was much publicity about its memory-free status. Today, it is known that this chemistry also suffers from memory but to a lesser extent than the NiCd. The positive nickel plate, a metal that is shared by both chemistries, is responsible for the crystalline formation.

New NiCd cell. (site has pics)

The anode is in fresh condition (capacity of 8.1Ah). Hexagonal cadmium hydroxide crystals are about 1 micron in cross section, exposing large surface area to the liquid electrolyte for maximum performance.

Cell with crystalline formation.

Crystals have grown to an enormous 50 to 100 microns in cross section, concealing large portions of the active material from the electrolyte (capacity of 6.5Ah). Jagged edges and sharp corners may pierce the separator, which can lead to increased self-discharge or electrical short.

Restored cell.

After pulsed charge, the crystals are reduced to 3 to 5 microns, an almost 100% restoration (capacity of 8.0A). Exercise or recondition are needed if the pulse charge alone is not effective.

Figure 10-1: Crystalline formation on NiCd cell.
Illustration courtesy of the US Army Electronics Command in Fort Monmouth, NJ, USA.

In addition to the crystal-forming activity on the positive plate, the NiCd also develops crystals on the negative cadmium plate. Because both plates are affected by crystalline formation, the NiCd requires more frequent discharge cycles than the NiMH. This is a non-scientific explanation of why the NiCd is more prone to memory than the NiMH.

The stages of crystalline formation of a NiCd battery are illustrated in Figure 10-1. The enlargements show the negative cadmium plate in normal crystal structure of a new cell, crystalline formation after use (or abuse) and restoration.

Lithium and lead-based batteries are not affected by memory, but these chemistries have their own peculiarities. Current inhibiting pacifier layers affect both batteries — plate oxidation on the lithium and sulfation and corrosion on the lead acid systems. These degenerative effects are non-correctible on the lithium-based system and only partially reversible on the lead acid.

[donaldekelly]

Credits:

Batteries in a Portable World 2nd Ed. - A Handbook on Rechargeable Batteries for Non-Engineers from Isidor Buchmann (Cadex Electronics Inc.).