Best practices for charging the PW2

FacebookVirus · 11-01-2013, 11:43 AM

The PW battery is said to last for weeks, but is it better for the battery to charge frequently?

I ask only because after two years my previous reader, the Sony T-1, began to suddenly lose charge while still showing multiple bars on its indicator. For almost two years I charged it only when needed, every few weeks.

Is is better for the PW battery to charge frequently or infrequently?

HarryT · 11-01-2013, 11:48 AM

It makes no difference to the lifespan of a lithium polymer battery, such as the PW2 uses, whether you top it up frequently, or let it discharge more fully and then recharge it. Do whatever suits you better.

sirmaru · 11-01-2013, 11:49 AM

Charge the PW 2013 when the 15% warning appears. It should last years if you do that.

However, with new models coming out annually, I doubt if anyone will keep it long enough to see the battery start to deteriorate.

jbcohen · 11-01-2013, 11:57 AM

Harry is right as usual, the term here in computer batteries is called battery memory, many years ago, I think it was back in the 90s or so. there were some batteries that needed to be fully discharged before re-charging. 21st century batteries have no battery memory and you can re-charge them from any point. I like to keep all my portable things fully charged: employer's blackberry, ipads, kindle and what not so I re-charge them every night to full charge. However there is absolutely no reason to do this, except for my employer's berry, the battery gets run down quite a bit while I am in the office so if I don't charge it at bed time it will never survive the next day, even if that days is a week-end.

FacebookVirus · 11-01-2013, 11:57 AM

Yes, I buy a new reader every couple of years, but I like to leave the old one in good shape for the next owner - and the resale value.

Thanks for the quick answers, HarryT and sirmaru.

jswinden · 11-01-2013, 12:16 PM

There is no battery memory issues in the Lithium Polymer batteries like there was in the Nickle based batteries. However, there has been a lot of research indicating that Lithium batteries last longer if you don't let them discharge more than half way before recharging. If you consistently wait until 15% charge is left, you can damage the battery. So best practice is to charge it before it reaches less than the half charged level. It doesn't matter how often you charge it and you certainly don't need to wait until it reaches 50%.

HarryT · 11-01-2013, 12:17 PM

Quote:

Originally Posted by jswinden

However, there has been a lot of research indicating that Lithium batteries last longer if you don't let them discharge more than half way before recharging. If you consistently wait until 15% charge is left, you can damage the battery.

Do you have any reference to such research, Jack? I haven't come across that, and I'd be interested to learn more about it.

jswinden · 11-01-2013, 12:29 PM

Quote:

Originally Posted by HarryT

Do you have any reference to such research, Jack? I haven't come across that, and I'd be interested to learn more about it.

Google it. We go through this stupid discussion once or twice a year. I found it when I was researching my Toyota Prius, which of course has a huge lithium battery. Toyota basically found that it would prolong battery life it they designed it to never fall below 50% charge, so they use a battery that is much larger than really needed so it can last longer.

sirmaru · 11-01-2013, 12:32 PM

Quote:

Originally Posted by jswinden

There is no battery memory issues in the Lithium Polymer batteries like there was in the Nickle based batteries. However, there has been a lot of research indicating that Lithium batteries last longer if you don't let them discharge more than half way before recharging. If you consistently wait until 15% charge is left, you can damage the battery. So best practice is to charge it before it reaches less than the half charged level. It doesn't matter how often you charge it and you certainly don't need to wait until it reaches 50%.

I've had Kindles and Sonys aplenty and always charged at 15%. So far not one battery has failed. Plus, I always charge my cell phones and Now Bibles at 15% as well. That Now Bible has been left at zero percent for years and always takes a full charge when needed and lasts just as long as when I first bought it.

There is probably a good reason that Amazon sends its charging warning on all its units at the 15% level.

Of course I have never kept any unit over 4 years.

I do keep detailed battery history for all types of devices in an Excel Spreadsheet so really know exact data in contrast to most who do not keep such records. I still have the records of devices long ago given away or thrown out.

I collect battery records as some others collect books.

Actually, I find battery technology is continuously improving. The newer devices last longer than the older devices.

HarryT · 11-01-2013, 12:34 PM

You are absolutely right in saying that a lithium battery shouldn't be fully discharged, but all modern batteries have built-in hardware protection to prevent that from happening. You can't discharge them below the "safe" level.

sirmaru · 11-01-2013, 12:43 PM

If one owns a Kindle Fire HDX 2013, they can get the GSam Battery Monitor for their unit which gives huge amounts of information on the battery including what is draining it and the projected hours for the battery to last.

Its unfortunate that the PW 2013 does not have Active Content to serve the same purpose.

I keep my PW 2013 and HDX 2013 in airplane mode when I sleep at night until the next morning. WiFi use does use lots of current when active.

One reason not to use the 50% level is to keep the battery METER calibrated. At 15% the meter will be re-calibrated in every cycle but at 50% the meter will lose its calibration.

jgsmith · 11-02-2013, 09:59 AM

There are 2 aspects to this:

1. As people have stated, these batteries no longer have memory. They do, however, have a happy place. They will deteriorate more quickly if discharged often or left discharged for a period of time. They are happiest in the 40-60% charged state. I let mine (not just PW2) get to about 1/3 battery remaining, then let it fully charge overnight. One caveat to this is point #2
2. All batteries degrade over time. Period. In order for your device to accurately display the actual charge remaining, it needs to know what state the battery is in. This is typically done by letting the battery drain to the point it powers off. Since batteries do not degrade quickly, and letting the battery get low is not ideal for the battery, this should only be done periodically. Say every 6 months or so.

Jim

JSWolf · 11-02-2013, 10:16 AM

One way to calibrate a battery is to charge it until it's full and then keep charging until the battery is fully charged in less then one minute. That way, the battery is fully charged like the device thinks it is.

jgsmith · 11-02-2013, 10:23 AM

Battery calibration is actually software calibration, and requires the device software to know a) where is the top end b) where is the bottom end and c) how long does it take to get from a to b.

Outrager · 11-02-2013, 07:52 PM

http://www.wired.com/gadgetlab/2013/09/laptop-battery/
This article is for laptop batteries, but I assume it would be the same for the Kindle and smartphones/tablets since they all use Lithium-ion polymer batteries.

Stop charge at 80%. Charge at 40%. That's optimal, but doesn't mean people will do that since it's kind of annoying. Also, the Kindle lasts so long those extra battery charges might not even matter.

11-01-2013, 11:43 AM	#1
FacebookVirus Hybrid reader Posts: 161 Karma: 1132216 Join Date: Sep 2013 Location: USA Device: Kindle Paperwhite 2; Sony PRS-350	Best practices for charging the PW2 The PW battery is said to last for weeks, but is it better for the battery to charge frequently? I ask only because after two years my previous reader, the Sony T-1, began to suddenly lose charge while still showing multiple bars on its indicator. For almost two years I charged it only when needed, every few weeks. Is is better for the PW battery to charge frequently or infrequently?

11-01-2013, 12:43 PM	#11
sirmaru Wizard Posts: 2,426 Karma: 6561538 Join Date: Nov 2007 Device: Kindle PW 2013, HDX 2013, Galaxy S5 2014	If one owns a Kindle Fire HDX 2013, they can get the GSam Battery Monitor for their unit which gives huge amounts of information on the battery including what is draining it and the projected hours for the battery to last. Its unfortunate that the PW 2013 does not have Active Content to serve the same purpose. I keep my PW 2013 and HDX 2013 in airplane mode when I sleep at night until the next morning. WiFi use does use lots of current when active. One reason not to use the 50% level is to keep the battery METER calibrated. At 15% the meter will be re-calibrated in every cycle but at 50% the meter will lose its calibration. Last edited by sirmaru; 11-01-2013 at 02:14 PM.

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11-01-2013, 11:48 AM	#2
HarryT eBook Enthusiast Posts: 85,544 Karma: 93383099 Join Date: Nov 2006 Location: UK Device: Kindle Oasis 2, iPad Pro 10.5", iPhone 6	It makes no difference to the lifespan of a lithium polymer battery, such as the PW2 uses, whether you top it up frequently, or let it discharge more fully and then recharge it. Do whatever suits you better.

11-01-2013, 11:49 AM	#3
sirmaru Wizard Posts: 2,426 Karma: 6561538 Join Date: Nov 2007 Device: Kindle PW 2013, HDX 2013, Galaxy S5 2014	Charge the PW 2013 when the 15% warning appears. It should last years if you do that. However, with new models coming out annually, I doubt if anyone will keep it long enough to see the battery start to deteriorate.

11-01-2013, 11:57 AM	#4
jbcohen Wizard Posts: 3,032 Karma: 11196738 Join Date: Oct 2010 Location: Where am I? Device: Kindle Paperwhite Signature edition and a Samsung S24 Ultra	Harry is right as usual, the term here in computer batteries is called battery memory, many years ago, I think it was back in the 90s or so. there were some batteries that needed to be fully discharged before re-charging. 21st century batteries have no battery memory and you can re-charge them from any point. I like to keep all my portable things fully charged: employer's blackberry, ipads, kindle and what not so I re-charge them every night to full charge. However there is absolutely no reason to do this, except for my employer's berry, the battery gets run down quite a bit while I am in the office so if I don't charge it at bed time it will never survive the next day, even if that days is a week-end.

11-01-2013, 12:16 PM	#6
jswinden Nameless Being	There is no battery memory issues in the Lithium Polymer batteries like there was in the Nickle based batteries. However, there has been a lot of research indicating that Lithium batteries last longer if you don't let them discharge more than half way before recharging. If you consistently wait until 15% charge is left, you can damage the battery. So best practice is to charge it before it reaches less than the half charged level. It doesn't matter how often you charge it and you certainly don't need to wait until it reaches 50%.

11-01-2013, 12:34 PM	#10
HarryT eBook Enthusiast Posts: 85,544 Karma: 93383099 Join Date: Nov 2006 Location: UK Device: Kindle Oasis 2, iPad Pro 10.5", iPhone 6	You are absolutely right in saying that a lithium battery shouldn't be fully discharged, but all modern batteries have built-in hardware protection to prevent that from happening. You can't discharge them below the "safe" level.

11-02-2013, 09:59 AM	#12
jgsmith Connoisseur Posts: 75 Karma: 233442 Join Date: Dec 2009 Location: Toronto, Canada Device: Sony PRS-600, Kobo Touch, Kindle PW2	There are 2 aspects to this: 1. As people have stated, these batteries no longer have memory. They do, however, have a happy place. They will deteriorate more quickly if discharged often or left discharged for a period of time. They are happiest in the 40-60% charged state. I let mine (not just PW2) get to about 1/3 battery remaining, then let it fully charge overnight. One caveat to this is point #2 2. All batteries degrade over time. Period. In order for your device to accurately display the actual charge remaining, it needs to know what state the battery is in. This is typically done by letting the battery drain to the point it powers off. Since batteries do not degrade quickly, and letting the battery get low is not ideal for the battery, this should only be done periodically. Say every 6 months or so. Jim

11-02-2013, 10:16 AM	#13
JSWolf Resident Curmudgeon Posts: 79,680 Karma: 145864619 Join Date: Nov 2006 Location: Roslindale, Massachusetts Device: Kobo Libra 2, Kobo Aura H2O, PRS-650, PRS-T1, nook STR, PW3	One way to calibrate a battery is to charge it until it's full and then keep charging until the battery is fully charged in less then one minute. That way, the battery is fully charged like the device thinks it is.

11-02-2013, 10:23 AM	#14
jgsmith Connoisseur Posts: 75 Karma: 233442 Join Date: Dec 2009 Location: Toronto, Canada Device: Sony PRS-600, Kobo Touch, Kindle PW2	Battery calibration is actually software calibration, and requires the device software to know a) where is the top end b) where is the bottom end and c) how long does it take to get from a to b.

11-02-2013, 07:52 PM	#15
Outrager Connoisseur Posts: 62 Karma: 12430 Join Date: Jun 2010 Device: Kindle Paperwhite 2013	http://www.wired.com/gadgetlab/2013/09/laptop-battery/ This article is for laptop batteries, but I assume it would be the same for the Kindle and smartphones/tablets since they all use Lithium-ion polymer batteries. Stop charge at 80%. Charge at 40%. That's optimal, but doesn't mean people will do that since it's kind of annoying. Also, the Kindle lasts so long those extra battery charges might not even matter.

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