does AC help prolong battery life?

ns66 · 08-18-2007, 07:27 PM

li-ion battery has limited recharge cycle, something like a few hundred recharges then the battery will die, i don't know whether sony sells battery ereader uses, it could mean after a few hundred charges ereader will be dead :P

i noticed even if your battery is drained, when you hook up the AC power, the battery indicator goes to full, i wonder in that case, does the ereader get the power directly from AC (bypass the battery all together), which seems to be rational things to do. if that's the case, when we read at home and by the power, keep AC power hooked on means not using battery that will help prolong battery life?

just a thought :P

HarryT · 08-19-2007, 02:57 AM

I would have thought that, if anything, constantly using the wall charger would shorten the battery life rather than lengthen it. I always try to let my Reader get down to 1 bar of charge before recharging which, for me, means that I charge about once every 3 weeks.

KlondikeGeoff · 08-19-2007, 12:02 PM

That really is an interesting question. Harry may well be right, but any electronics gurus know for sure?

Should the AC bypass the battery, I'd use it often. One good thing is that Sony's charger has nice long cord.

Somehow I wonder, as once the LED light goes out, I notice the transformer no longer is warm. On the other hand, constant reading might cycle it on and off, who knows? That is a literal question: Who Knows?

yvanleterrible · 08-19-2007, 12:40 PM

Air Conditionning won't do a thing for the reader.

KDawg · 08-19-2007, 12:50 PM

Quote:

Originally Posted by HarryT

I would have thought that, if anything, constantly using the wall charger would shorten the battery life rather than lengthen it. I always try to let my Reader get down to 1 bar of charge before recharging which, for me, means that I charge about once every 3 weeks.

I think the net wisdom (batteryuniversity.com, wikipedia, etc.) on LiIon and Lithium Polymer batteries is that frequent, shallow discharges are better than rarer, deep discharges with regards to service life. I.e., the battery will be in better shape after 600 half-discharges than 300 full-discharges. And what really kills laptop batteries is heat. When operating on AC, the average laptop dumps so much heat into the battery that the service life of the battery is affected more by that heat than discharge/charge habits.

Now my guess, and it's only a guess: The Sony's battery life is extended by operating on AC. The charger tops off the LiIon battery and then turns off. After that the Reader is operating on AC and it is so low-powered that the heat dumped into the battery during operation is negligible. So by operating on AC you're not using up discharge/charge cycles, thus extending the battery service life.

KDawg · 08-19-2007, 12:55 PM

Quote:

Originally Posted by KlondikeGeoff

That really is an interesting question. Harry may well be right, but any electronics gurus know for sure?

Should the AC bypass the battery, I'd use it often. One good thing is that Sony's charger has nice long cord.

Somehow I wonder, as once the LED light goes out, I notice the transformer no longer is warm. On the other hand, constant reading might cycle it on and off, who knows? That is a literal question: Who Knows?

Another guess on my part: the power (really current in a given time) needed to charge the Reader's battery dwarfs the power needed to read. Now I'm going to have to charge and read on AC with my hand on the transformer and see what happens. I may dig my Kill-o-Watt out of our packed boxes although it may not read current as low as what the Reader uses when just reading.

paulkbiba · 08-19-2007, 03:35 PM

If you want to know anything about battery life and charging take a look at

batteryuniversity.com

The site is run by a manufacturer of battery chargers and analyzers and I've found it to be a wonderful source of knowledge.

UncleDuke · 08-19-2007, 04:09 PM

Quote:

Originally Posted by ns66

li-ion battery has limited recharge cycle, something like a few hundred recharges then the battery will die, i don't know whether sony sells battery ereader uses, it could mean after a few hundred charges ereader will be dead :P

i noticed even if your battery is drained, when you hook up the AC power, the battery indicator goes to full, i wonder in that case, does the ereader get the power directly from AC (bypass the battery all together), which seems to be rational things to do. if that's the case, when we read at home and by the power, keep AC power hooked on means not using battery that will help prolong battery life?

just a thought :P

if it is just a few hundred then my reader must be almost dead since i have almost 200 recharges <everytime i plug it into usb> but it still works fine

i have a radio that also has recharge batteries and it has been recharged over a thousand times with no ill effects, ditto for my 4 year old cell phone, i should get a new one soon

Dr. Drib · 08-19-2007, 05:56 PM

Regarding full recharges (and I'm like Harry in that I let the bar go down to 1 and then charge through the wall), I think I've done probably 10 or 11 since I bought my Reader in late December of last year.

When you think about it, if one can get approx. 200 charges on these batteries before they start to no longer hold a charge, then that would give me about 10 years before I have to send it in for a new factory battery.

Don

marsonist · 08-20-2007, 11:24 AM

I don't engineer batteries, so I don't have any insider info, but as a technophile I've done a bit of research on the topic.

Lithium-Ion batteries, such as what you find in the Sony Reader and iPods, do have a limited amount of full charges. The key word, however, is full. As many people with old iPods will tell you they still charge and still function. They simply hold less of a charge than when they were brand new. After 300 full charges you may find yourself only getting 60-70% of your original battery life.

The main factor in determining how well your battery holds is not whether you wait until it's fully drained or choose to keep it topped off. It's heat. If topping off the battery keeps it cooler to the touch when it's charging, then do that. If it doesn't make a difference, then it doesn't make a difference.

Charging 10% of a full battery counts as 10% of a full charge. If you should get 300 full charges, then you should get 3000 10% charges.

Again, the months and years of heat exposure will affect battery life the most. And don't worry about that 300 count. You're device won't stop working on charge 301

yvanleterrible · 08-20-2007, 11:32 AM

Nicely put Marsonist!

We should have a battery chapter in our Wiki, they are an intrinsic part of mobile reading. Any one up for it?

NatCh · 08-20-2007, 01:05 PM

You brought it up, yvanleterrible ....

Either way, as someone said before, 300 charges at 3 weeks between charges brings me to ... something over 17 years of use on the original battery before I only start getting, what? Only two weeks per charge? Anyway, in 17 years, someone will be third-partying the battery, or it'll have been replaced with something better. Or more likely, a much advanced reader will have come along, and the PRS-500 will be another member of my personal Gadget Archive, next to my Pilot 5000. And after 17 years of use, it'll be hard to argue that it wasn't worth the investment.

yvanleterrible · 08-20-2007, 01:59 PM

I only know how to use tool NiCad's, so I'm far from competent enough for a Wiki on anything else than furniture building.

ns66 · 08-20-2007, 08:37 PM

at my rate of using, i have to charge every few days, last less than a week definitely

Aprilbeginnings · 08-21-2007, 10:41 AM

So what happens when the battery finally does die? I don't think I would want to open it up and try changing it. Would I have to take it to the Sony store where I got it and have them do it or what?

Hoping the sucker never does ever die out.....

08-18-2007, 07:27 PM	#1
ns66 Connoisseur Posts: 78 Karma: 156 Join Date: Jul 2007 Device: sony reader	does AC help prolong battery life? li-ion battery has limited recharge cycle, something like a few hundred recharges then the battery will die, i don't know whether sony sells battery ereader uses, it could mean after a few hundred charges ereader will be dead :P i noticed even if your battery is drained, when you hook up the AC power, the battery indicator goes to full, i wonder in that case, does the ereader get the power directly from AC (bypass the battery all together), which seems to be rational things to do. if that's the case, when we read at home and by the power, keep AC power hooked on means not using battery that will help prolong battery life? just a thought :P

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08-19-2007, 02:57 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	I would have thought that, if anything, constantly using the wall charger would shorten the battery life rather than lengthen it. I always try to let my Reader get down to 1 bar of charge before recharging which, for me, means that I charge about once every 3 weeks.

08-19-2007, 12:02 PM	#3
KlondikeGeoff Wombat Aficionado Posts: 481 Karma: 733 Join Date: Nov 2006 Location: Arizona Device: Fire, Kindle1, Sony PRS-500 Reader, Rocket 1100 eBook	That really is an interesting question. Harry may well be right, but any electronics gurus know for sure? Should the AC bypass the battery, I'd use it often. One good thing is that Sony's charger has nice long cord. Somehow I wonder, as once the LED light goes out, I notice the transformer no longer is warm. On the other hand, constant reading might cycle it on and off, who knows? That is a literal question: Who Knows?

08-19-2007, 12:40 PM	#4
yvanleterrible Reborn Paper User Posts: 8,616 Karma: 15446734 Join Date: May 2006 Location: Que Nada Device: iPhone8, iPad Air	Air Conditionning won't do a thing for the reader.

08-19-2007, 03:35 PM	#7
paulkbiba Connoisseur Posts: 84 Karma: 45 Join Date: Aug 2005 Location: United States Device: Nokia e61i, iPhone	If you want to know anything about battery life and charging take a look at batteryuniversity.com The site is run by a manufacturer of battery chargers and analyzers and I've found it to be a wonderful source of knowledge.

08-19-2007, 05:56 PM	#9
Dr. Drib Grand Sorcerer Posts: 45,398 Karma: 59504381 Join Date: Jan 2007 Location: Peru Device: KINDLE: Oasis 3, Scribe (1st), Matcha; KOBO: Libra 2, Libra Colour	Regarding full recharges (and I'm like Harry in that I let the bar go down to 1 and then charge through the wall), I think I've done probably 10 or 11 since I bought my Reader in late December of last year. When you think about it, if one can get approx. 200 charges on these batteries before they start to no longer hold a charge, then that would give me about 10 years before I have to send it in for a new factory battery. Don

08-20-2007, 11:24 AM	#10
marsonist Junior Member Posts: 2 Karma: 10 Join Date: Feb 2007 Device: PRS-500	I don't engineer batteries, so I don't have any insider info, but as a technophile I've done a bit of research on the topic. Lithium-Ion batteries, such as what you find in the Sony Reader and iPods, do have a limited amount of full charges. The key word, however, is full. As many people with old iPods will tell you they still charge and still function. They simply hold less of a charge than when they were brand new. After 300 full charges you may find yourself only getting 60-70% of your original battery life. The main factor in determining how well your battery holds is not whether you wait until it's fully drained or choose to keep it topped off. It's heat. If topping off the battery keeps it cooler to the touch when it's charging, then do that. If it doesn't make a difference, then it doesn't make a difference. Charging 10% of a full battery counts as 10% of a full charge. If you should get 300 full charges, then you should get 3000 10% charges. Again, the months and years of heat exposure will affect battery life the most. And don't worry about that 300 count. You're device won't stop working on charge 301

08-20-2007, 11:32 AM	#11
yvanleterrible Reborn Paper User Posts: 8,616 Karma: 15446734 Join Date: May 2006 Location: Que Nada Device: iPhone8, iPad Air	Nicely put Marsonist! We should have a battery chapter in our Wiki, they are an intrinsic part of mobile reading. Any one up for it?

08-20-2007, 01:05 PM	#12
NatCh Gizmologist Posts: 11,615 Karma: 929550 Join Date: Jan 2006 Location: Republic of Texas Embassy at Jackson, TN Device: Pocketbook Touch HD3	You brought it up, yvanleterrible .... Either way, as someone said before, 300 charges at 3 weeks between charges brings me to ... something over 17 years of use on the original battery before I only start getting, what? Only two weeks per charge? Anyway, in 17 years, someone will be third-partying the battery, or it'll have been replaced with something better. Or more likely, a much advanced reader will have come along, and the PRS-500 will be another member of my personal Gadget Archive, next to my Pilot 5000. And after 17 years of use, it'll be hard to argue that it wasn't worth the investment.

08-20-2007, 01:59 PM	#13
yvanleterrible Reborn Paper User Posts: 8,616 Karma: 15446734 Join Date: May 2006 Location: Que Nada Device: iPhone8, iPad Air	I only know how to use tool NiCad's, so I'm far from competent enough for a Wiki on anything else than furniture building.

08-20-2007, 08:37 PM	#14
ns66 Connoisseur Posts: 78 Karma: 156 Join Date: Jul 2007 Device: sony reader	at my rate of using, i have to charge every few days, last less than a week definitely

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08-21-2007, 10:41 AM	#15
Aprilbeginnings Guru Posts: 632 Karma: 404 Join Date: Nov 2006 Location: Southern CA Device: Sony PRS-500 /prs 650 soon	So what happens when the battery finally does die? I don't think I would want to open it up and try changing it. Would I have to take it to the Sony store where I got it and have them do it or what? Hoping the sucker never does ever die out.....