battery life (not charge life)

[soondai]

I'm about to get an e-reader. At the new price and given how satisfied everyone on these boards seems with it, I think it's probably going to be the Kindle.

However it seems really strange to me that you can't change the battery yourself and have to send it in (and fork over 60 bucks) to do so.

Just curious about hear from the K2 owners: how long does it last/have you had to replace it?

I'll probably be using it almost exclusively as a reader w/ the wifi turned off. So if I only have to charge it once a month or so can I expect the battery to last for several years?

[sirmaru]

Most Lithium batteries can take 500 recharges before dying. Thus, it pays to let the battery run down to one bar before recharging.

I keep eReaders in shutdown mode when not in use to minimize discharge and, thus, minimize the number of recharges.

My Sony PRS 900 goes between 56 to 89 days between recharges using that doctrine. I expect my Kindle 3 to do the same.

[daffy4u]

The battery can actually be changed by the user without too much difficulty. You can about how here.

I have an early K2 US and have not had any battery issues in the 18 months I've owned it.

[norti]

Originally Posted by sirmaru

Most Lithium batteries can take 500 recharges before dying. Thus, it pays to let the battery run down to one bar before recharging.

Only the cheap ones. I have my Xperia since 1998 and the battery is still on top with charging it every day (I'm a heavy user), it still works with normal use up to 3 days. That's at least 700 charges. So if you charge it normally - when the battery is very low - and the battery is not a cheap one, you can live with it "forever" or at least until you buy a new generation device instead

[soondai]

sounds good. thanks for all the info. can't wait to get the overall scoop once they start rolling in. I'll probably have to wait until my Oct b-day to get my hands one.

[HarryT]

Originally Posted by sirmaru

Most Lithium batteries can take 500 recharges before dying. Thus, it pays to let the battery run down to one bar before recharging.

No, that's not true. Lithium Polymer batteries such as the Kindle uses don't mind being "topped up" at all, and it has no impact on battery life. It really doesn't matter whether you top it up every day, or you let it drain before recharging it; the battery life will still be the same.

[patrickt]

I'm new to Kindle so it's nice to have the facts. I can charge my Kindle between 500 times and an unlimited number of times. I can expect to recharge it between every 3 days and every 89 days.

[schulzmc]

The "how many charge cycles" statistic can be misleading. If you top off your battery (which, as was said above, it is fine to do with K2 and K3 batteries) it does not count as a charge cycle... at least not a full one.

Let's say you use 10% of the battery every day and top it off every night. After 10 days of this you will have "used up" ONE of the charge cycles. (10x10%=100%) So if indeed the battery can handle 500 charge cycles (I've heard more) you still have 499. At that rate the battery will last about 14 years!

Enough about math. In reality, I've had a K2 since launch day and I give it a full charge every time it gets to about 50% (just because it is a convenient time interval for me) and it shows no sign of not holding a charge. I don't anticipate every having to have the battery changed.

[HarryT]

Regardless of charge cycles, lithium batteries do degrade over time. The clock starts "ticking" the first time the battery is charged, and there's no way it can be stopped. You could reasonably expect a good quality lithium polymer battery to have lost perhaps a third to a half of its original capacity after 3 years.

[sirmaru]

Originally Posted by HarryT

Regardless of charge cycles, lithium batteries do degrade over time. The clock starts "ticking" the first time the battery is charged, and there's no way it can be stopped. You could reasonably expect a good quality lithium polymer battery to have lost perhaps a third to a half of its original capacity after 3 years.

Charge life of the battery is probably not why we replace the eReader. I just purchased my Sony PRS 900 with case in December, 2009, for $ 400 and now, in my opinion, the Kindle 3 LG WiFi with case goes for $ 180 and probably beats the Sony for portablity and readability.

I had purchased a Sony PRS 505 just 10 months prior to the PRS 900.

I expect that by the end of 2011, I'll be dumping the Kindle 3 to buy another eReader - brand still undetermined.

Thus, battery life is IRRELEVANT. Obsolescence causes all electronic gadgets to be dumped for GPS devices, PC's, cell phones and eReaders.

If not for obsolesence, I'd still be using my Radio Shack TRS-80 16 Kb with DOS 1.0 8 bit from 1979 instead of my Dell Minitower XPS 7100 1.5 Tb with Windows 7 64 bit.

The 500 charge limit was stated in my NowBible manual which also uses a high grade lithium polymer battery and EXPRESSLY stated that information. I use that one daily with a dramatized sound broadcast of the Bible over one year. I use that battery until it runs totally dead. I get 22 days using it that way until the charge is required. I do recharge it weekly if I have a Bible Study to attend that week. I've been using that device since 3/22/2010 to the present and have recharged it only 14 times. If I have to charge it at that rate, it will average about 30 times per year. It could last over 10 years at that rate. However, it will also be OBSOLETE in about 12 to 24 months.

[soondai]

Originally Posted by sirmaru

I expect that by the end of 2011, I'll be dumping the Kindle 3 to buy another eReader - brand still undetermined.

Thus, battery life is IRRELEVANT. Obsolescence causes all electronic gadgets to be dumped for GPS devices, PC's, cell phones and eReaders.

I want a reader to read on. If it can hold a lifetime of books, I'll probably keep it for a lifetime (mine or its). So it is very relevant to me.

I expect anything I fork over 100 dollars for to still be functional in 5 years (though I don't expect the battery to last that long of course).

But it sure sounds like the battery won't be a problem.

[TomF]

Originally Posted by sirmaru

However, it will also be OBSOLETE in about 12 to 24 months.

Obsolete is a pretty strong word to use for electronic devices. Useful life would be more accurate. Electronic devices continue to do what they were designed to do at the time they were purchased. Just because a newer model is introduced doesn't make the previous model obsolete.

There are some people who are still reading on the original Kindle that they bought when they were brand new and that was more than three years ago. Are they obsolete? No, because they still perform the same function as they did when they were new.

The cell phone I bought 10 years ago would still function if I re-activated it. Is it obsolete? It would only be obsolete if the band on which it operated were no longer available or the battery died and I couldn't find a new battery.

My father-in-law was still using Windows 98 up until last year even though Microsoft has long since stopped supporting it. He could still send and receive e-mail, browse the Web, run the programs that he bought to run on Win98.

Of course I long ago decided that OS was obsolete for me.

[Vertigo]

Litium ion batteries do not have a 'memory' like the old NiMH or NI-Cad batteries:

A lithium-ion battery provides 300-500 discharge/charge cycles. The battery prefers a partial rather than a full discharge. Frequent full discharges should be avoided when possible. Instead, charge the battery more often or use a larger battery. There is no concern of memory when applying unscheduled charges.

Although lithium-ion is memory-free in terms of performance deterioration, batteries with fuel gauges exhibit what engineers refer to as "digital memory". Here is the reason: Short discharges with subsequent recharges do not provide the periodic calibration needed to synchronize the fuel gauge with the battery's state-of-charge. A deliberate full discharge and recharge every 30 charges corrects this problem. Letting the battery run down to the cut-off point in the equipment will do this.