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Battery-when to charge?

CMFox

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This certainly seems like a stoopid question, but the more I try to figure this out the more I don't get it. I've read the posts on this forum, read Apple's battery info and I'm more confused for all this info.

What I think I know:
Apple recommends 1x a month running the iPad's battery down to 0, till it shuts off and then recharge back to 100%. This helps the battery maintain its full charging capacity for longer.

Then the area that gets so grey:
In the past with an electronic device like my phone or camera or laptop, whether I use em some, a lot, a little-during the day, once home I charge them up for the next day. Regardless of whether they need charging or not, I will "top them off" to start at 100% charged in the morning.

But with an iPad should we keep running the battery down until it gets to 20%, 10%, 5% before recharging it. OR?! is it okay to plug it in in the evening b4 bed, even if its at 75%, or 63% and "top it off" for the next day?

CM
battery illiterate or perhaps over thinking things?
 

Matth3w

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I'm like you in that I top off my phone every night. I don't do it to my iPad, but only because normal use I usually get 3 days of charge out of it.

Don't worry about plugging it in, there are circuits that prevent it from overcharging.

All batteries have a finite lifespan, true...but that lifespan is not going to be such that by charging your iPad every night if you so desire that your battery is going to be dead in 6 months of even a year.

The iPhone has been out since 2007ish, and if that was the case you would see people complaining all over the place about how their battery has gone to crap.

It's certainly not a stupid question, as the only stupid question is the one not asked (I know it's cliche, but for the most part it's true), so I think you are just worrying about it a little too much. You're fine in topping it off every night. If I needed to, I would do the same. I just know unless I am traveling that it is going to make it several days on one charge so I'm too lazy to charge it lol. I leave it in my stand on my computer desk most nights.
 

Abrennan

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I thought that a few years ago they started making batteries that didn't need to be powered down totally as the memory function of batteries had been improved. I guess it may be that seeing as the iPad is always on, even when the screen is powered off, the battery needs some form of maintenance like a reboot.
 

Gabi

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Hmmm, I never let it it go down to 0% yet. I guess I should do it once a month ...?
 

Roundplay

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I always wondered about this with apple laptops. Because most people I know leave them plugged in almost all day at the office, except when going to a meeting or conference room. Does that hurt the battery to leave it always plugged in? Is it a waste of energy, or is it run off the plug power and conserve the battery?
 
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CMFox

CMFox

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Ah....so I'm not the only one confused about batteries.

Matthew's answer was most reassuring.

I too, wonder about letting the iPad run down to zero....or do them mean something less then zero.(see the bottom of this page: Apple - Batteries - iPad)

As for my laptop, I too keep it plugged in and don't run it all the way down ever.

CM
 

monkeyboy

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Its strange that Apple recommends a "deep discharge" once a month because that is not what the battery experts say about lithium batteries. Lithium batteries are supposed to be damaged by deep discharges, unlike NiCd and NiMH, and instead are much happier with "topping off".

Lithium cells are also damaged by "trickle charging", unlike NiCd, NiMH and lead-acid. Many charging systems seem to get this part wrong. I've seen many laptop batteries die within 6mos (IBM seems to be one culprit) because owners would leave the laptop charging overnight or 24/7. Because of this, I instinctively do not let my Li-powered devices charge any more than needed and I try to avoid overnight charging. Leaving a Li battery charging overnight means that you trust the charging circuit designed to detect a full condition accurately and not let any additional current in -- some devices seem to be well designed, others not so... I have Li batteries still good from 14+ years ago.

With the iPad, I'm generally running it down to about 30-40% before recharging and then trying to charge it during "waking hours" so I can remove the charge close to when it is full, +/-. We'll see with the iPad just how well designed the charging circuit is... given that it is a non-user-replaceable battery, the right practices are even more critical.
 
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Matth3w

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Please avoid spreading incorrect information if you can.



There are overcharging circuits, you don't need to worry about this sort of thing.

[FONT=Verdana, Arial, Helvetica, sans-serif]Much attention is focused to avoid over-charging and over-discharging. Commercial lithium ion packs contain a protection circuits that limit the charge voltage to 4.30V/cell, 0.10 volts higher than the voltage threshold of the charger. Temperature sensing disconnects the charge if the cell temperature approaches 90°C (194°F), and a mechanical pressure switch on many cells permanently interrupt the current path if a safe pressure threshold is exceeded. Exceptions are made on some spinel (manganese) packs containing one or two small cells. [/FONT]
[FONT=Verdana, Arial, Helvetica, sans-serif]Should I charge my battery partially or fully?

[/FONT][FONT=Verdana, Arial, Helvetica, sans-serif]Does not matter. Charging in stages is acceptable. Full charge termination occurs by reading the voltage level and charge current. Charging a full battery is safe and does not cause harm. [/FONT]
[FONT=Verdana, Arial, Helvetica, sans-serif]- Should I remove the battery from the charger when full?

[/FONT][FONT=Verdana, Arial, Helvetica, sans-serif]It does not matter. The charger automatically cuts the charge current when the battery is full.[/FONT]
You are also wrong about the full discharge as well:

[FONT=Verdana, Arial, Helvetica, sans-serif]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. If ignored, the fuel gauge will become increasingly less accurate. (Read more in 'Choosing the right battery for portable computing', Part Two.) [/FONT]
[FONT=Verdana, Arial, Helvetica, sans-serif]Should I use up all battery energy before charging?

[/FONT][FONT=Verdana, Arial, Helvetica, sans-serif]No, it is better to recharge more often; avoid frequent full discharges.
Yes, on batteries with a fuel gauge, allow a full discharge once a month to enable reset
[/FONT]
In other words, just about your entire post was incorrect.

I highly suggest an education at http://www.batteryuniversity.com

I don't mean to be harsh, but hearsay without facts to back up your assertions leads many users, especially new users, astray. Apple has it set up the way it is for a reason.

Most LiIon batteries last 2-3 years or more or 300-500 discharge cycles or more, provided you follow the above guidelines.
 
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mslammers

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LiOn Batteries

Please avoid spreading incorrect information if you can.



There are overcharging circuits, you don't need to worry about this sort of thing.

[FONT=Verdana, Arial, Helvetica, sans-serif]Much attention is focused to avoid over-charging and over-discharging. Commercial lithium ion packs contain a protection circuits that limit the charge voltage to 4.30V/cell, 0.10 volts higher than the voltage threshold of the charger. Temperature sensing disconnects the charge if the cell temperature approaches 90°C (194°F), and a mechanical pressure switch on many cells permanently interrupt the current path if a safe pressure threshold is exceeded. Exceptions are made on some spinel (manganese) packs containing one or two small cells. [/FONT]
[FONT=Verdana, Arial, Helvetica, sans-serif]Should I charge my battery partially or fully?

[/FONT][FONT=Verdana, Arial, Helvetica, sans-serif]Does not matter. Charging in stages is acceptable. Full charge termination occurs by reading the voltage level and charge current. Charging a full battery is safe and does not cause harm. [/FONT]
You are also wrong about the full discharge as well:

[FONT=Verdana, Arial, Helvetica, sans-serif]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. If ignored, the fuel gauge will become increasingly less accurate. (Read more in 'Choosing the right battery for portable computing', Part Two.) [/FONT]
[FONT=Verdana, Arial, Helvetica, sans-serif]Should I use up all battery energy before charging?

[/FONT][FONT=Verdana, Arial, Helvetica, sans-serif]No, it is better to recharge more often; avoid frequent full discharges.
Yes, on batteries with a fuel gauge, allow a full discharge once a month to enable reset
[/FONT]
In other words, just about your entire post was incorrect.

I highly suggest an education at Welcome to Battery University

I don't mean to be harsh, but hearsay without facts to back up your assertions leads many users, especially new users, astray. Apple has it set up the way it is for a reason.

Most LiIon batteries last 2-3 years or more or 300-500 discharge cycles or more, provided you follow the above guidelines.
Canon Camera says that if you don't fully discharge and then recharge when you first get one of their new smart batteries, you run the risk of the % charge value being inaccurate. The battery works just as good, you "may" notice that the % charge is slightly off. If that matters to you, follow their suggestion.
All LiOn batteries have a cut off to prevent the battery from overheating and catching fire as sometimes happened years ago when the LiOn batteries were first used. Their use was suspended for a while until that got fixed. There is still an occasional overheating problem as was noticed with Apple notebooks a year or more ago. Again a short time problem that quickly got fixed. A recall I believe.
Note that I am not a LiOn battery nor do I play one on TV, but I do have many that I use. Never had an overheating problem.
Cheers.
 

Matth3w

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I didn't indicate there a problem with overheating or are you referring to someone else?
 

MikesTooLz

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The batteries are ok if you don't run them down to 0%. What I do is use it during that day and leave it to charge over night while I sleep.

While there is no need to bring the battery down to 0% it is a good idea to do so once and a while. I only do it maybe once or twice per year on purpose and then it happens on its own a few other times just from me being away from a power source or not having the charger with me while I use it all day.

The reason for doing this is that those electrons in the battery that don't ever get used just sit there and over time may not flow out as well causing the battery not to last as long as a full charge should last. A full discharge and recharge gets new electrons flowing into the battery. So its not something that is permanent, a discharge and recharge should clear out the old electrons.



I wouldnt worry about the battery, its covered for a year by apple and they will replace it if it starts to not old a charge for as long as it should. You also have up until the end of that year to purchase their 2 year extended coverage. I never get the 2 year coverage plan because I always end up buying the new model with better features each year.
 
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mslammers

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I didn't indicate there a problem with overheating or are you referring to someone else?

Matt, I just put all the previous msgs in since they covered the waterfront. I knew you didn't mention overheating. I also was trying to follow your guidance about not spreading incorrect info. I probably should have been more thorough.
Mel
 

monkeyboy

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Please avoid spreading incorrect information if you can.

In other words, just about your entire post was incorrect.

I highly suggest an education at Welcome to Battery University

I don't mean to be harsh, but hearsay without facts to back up your assertions leads many users, especially new users, astray.
Despite your harsh? reply, I still believe that everything I stated is true, though admittedly not all relevant to ipad users. Your main source seems to be batteryuniversity.com, which itself advertises its disclaimer as:

[FONT=Verdana, Arial, Helvetica, sans-serif]Since BatteryUniversity bases its information on the feedback from users as opposed to scientific information derived from a research lab, longevity results may differ from manufacturer' specifications.[/FONT]
I'll admit that I had forgotten about the "digital memory" issue, in part because it is a SOFTWARE issue and isn't about lithium cells per se. Yes, SOME software "fuel gauge" algorithms fall prey to losing track of actual battery capacity and therefore benefit from a "reset" by a monthly deep discharge. It is a SOFTWARE problem and the battery itself DOES NOT benefit from deep discharges. Indeed as you have quoted, deep discharges are to be AVOIDED:
[FONT=Verdana, Arial, Helvetica, sans-serif]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.[/FONT]
Not all "fuel gauges" suffer from "digital memory". If Apple advises monthly deep discharges, it must be that their SOFTWARE algorithm does have that potential issue. I did not claim any specific knowledge about Apple's battery algorithms.

As far as the overcharging issue, yes, a *properly* designed device does shut off the charging current to prevent overcharging. If you wish to claim that the ipad *is* such a properly designed device, I have no evidence to the contrary. I have *plenty* of evidence that there are many poorly designed charging circuits out there in common electronic equipment, such as laptops. These *do* damage lithium batteries such that 24/7 connection to AC power results in battery death in a year or less. Overheating circuits, often incorporated into the Li batteries themselves are NOT a replacement nor adequate to prevent chronic overcharging. That is the job of the charging circuit and its algorithms, which can be quite complex (a thermosensor is NOT adequate).

Batteryuniversity shows such data as well: How to prolong lithium-based batteries, the chart in the middle of this page documents 65% capacity loss after 1 year with 100% charge at 40degC, which is not an uncommon set of conditions for some equipment.

Nevertheless, I have no reason to suspect that Apple has designed the ipad battery circuits poorly -- so leaving it plugged in overnight is probably fine. And once/month deep discharges? Fine... I still say that frequent deep discharges are generally recognized to be bad for lithium cells.
 

Matth3w

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Do what you will, it's of no consequence to me.
 
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