Running Battery to Zero

[slothead]

The other day C4 mentioned that Apple recommends running the battery to zero to help the system remember what zero is... for the battery (calibration). Has anyone else done this, and do I need to be concerned about backing up on iTunes before letting it get that low? I generally avoid letting batteries that far down, but if Apple says so... So be it.

 

[iPadCharlie]

Just so you know I am not making this stuff up....

This is from the Apple website --

Use Your iPad Regularly
For proper reporting of the battery’s state of charge, be sure to go through at least one charge cycle per month (charging the battery to 100% and then completely running it down).

Here is the link to the page with tips for maximizing the iPad battery life --

Apple - Batteries - iPad

I have done this several times with no problems at all. Of course it won't hurt to back up your iPad before letting it run down. Consider it cheap insurance!

I generally set the Auto-lock time to Never so the screen stays on and just let it go until it shuts off. Theoretically, the battery in the iPad is supposed to last 1000 complete charge/discharge cycles before the battery needs to be replaced (which they define as being able to hold 80% of its original charge). At this rate, it will probably outlast the battery I just put in my car last month!

 

[slothead]

Hey I trusted you C4! Right now I am at 19% and dropping (probably won't get to 0 before I leave for home), so I think I'll back her up on iTunes right now. I forgot I had the iTunes laptop here today.

Thanks again,

 

[IPad-Fan-64]

I have let the iPad run down to 0 a few times and havnt had any problems when fully charged.

 

[pluto6]

Far be it for me to argue with C -4, so I won't. I'm not sure what the reason why would be, as theoretically the lithium batteries don't have memory, so there is no reason for them to remember what 100% is... However, I think that the system has problems remembering what 100% is, and letting the battery run all the way down (which I do) helps with a better charge, but the system software will shut off the charge when it thinks the battery is 100%, regardless of whether is or not, and it will also shut off the iPad when it thinks that the battery is too low, again regardless of whether or not it is.

I have had personal experience with my iPad "thinking" it was dead, and needing to do a restore, and then the battery was 100%, even though I did not charge it, I just reset the software... So, the once a month rule is probably good to live by.

 

[DaveSt]

It doesn't really have anything to do with charging the battery, it is only to calibrate the battery meter on the device that estimates the percentage of battery life you have left. The battery is charged through an electronic circuit that isn't affected by this status whatsoever. If you don't mind your meter being off a couple of percentage points you can forgo the monthly battery drain and rest assured your charge cycle is working properly.

 

[PhotoJim]

Lithium batteries have longer lives if they're topped up regularly and not drained completely. I've got lithiums that are five years old that still work reasonably well because I've treated them this way.

Your scale might get inaccurate if you do this a lot, but that's not that important in my opinion.

You can drain your battery right down every few months if you care about the scale.

 

[graywolf]

Some people say it is for the calibration and some say it is for the battery. C4 is right, it is for both. Your iPad needs to figure out what battery output is what percent and lithium polymer batteries need a full charge and drain every month or so to stay efficient and to last longer. Photojim is also right. Lithium polymer and lithium ion batteries should be run to halfway or more and then charged some or all the way up. But don't forget your month or so full charge and drain.

 

[SweetPoison]

Mine kicks off at 2%. Never makes it to zero.

 

[DaveSt]

Some people say it is for the calibration and some say it is for the battery. C4 is right, it is for both. Your iPad needs to figure out what battery output is what percent and lithium polymer batteries need a full charge and drain every month or so to stay efficient and to last longer. Photojim is also right. Lithium polymer and lithium ion batteries should be run to halfway or more and then charged some or all the way up. But don't forget your month or so full charge and drain.

Doing a deep discharge on a LiPo battery will NOT increase or maintain efficiency. In fact quite the opposite is true. Every deep discharge of a LiPo battery degrades the battery pack a tiny little bit. The only reason to do a deep discharge is to calibrate the power meter. If you want the longest life out of your battery and you don't mind the meter being off a little bit, just keep the battery topped off. Numerous small charges are better than deep discharges. I think companies are doing a disservice to their customers by making them think these monthly deep discharges are somehow needed. They most certainly are not, and if you use LiPo batteries for industrial applications (although most companies including mine have stopped using them for litigation reasons .. they are quite dangerous) you will find the suppliers recommend never doing full discharges. If the full discharge for calibration is mentioned at all, generally a full discharge every 5-6 months is the recommendation. Then again, those suppliers aren't getting $99 a pop to replace dead battery packs either.

 

[iPadCharlie]

Just to clear things up, I posted a link to Apple's website that claims that doing a complete cycle of the battery is only for calibrating the meter. Nowhere does it say it has anything to do with battery efficiency.

Most of the tips on that page have more to do with minimizing those apps and situations that can cause an unnecessary drain on the battery.

 

[graywolf]

Doing a deep discharge on a LiPo battery will NOT increase or maintain efficiency. In fact quite the opposite is true. Every deep discharge of a LiPo battery degrades the battery pack a tiny little bit. The only reason to do a deep discharge is to calibrate the power meter. If you want the longest life out of your battery and you don't mind the meter being off a little bit, just keep the battery topped off. Numerous small charges are better than deep discharges. I think companies are doing a disservice to their customers by making them think these monthly deep discharges are somehow needed. They most certainly are not, and if you use LiPo batteries for industrial applications (although most companies including mine have stopped using them for litigation reasons .. they are quite dangerous) you will find the suppliers recommend never doing full discharges. If the full discharge for calibration is mentioned at all, generally a full discharge every 5-6 months is the recommendation. Then again, those suppliers aren't getting $99 a pop to replace dead battery packs either.

Sorry, efficiency wasn't quite the right word. But yes it is all for the calibration.

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