Iphone, Ipad, etc battery questions

A fellow at work just bought the new iPhone 4s. Some other worker told him " make sure you run the battery right down before you charge it".
I thought this was a wrong comment, as with our flashlight Li batteries, we have been told not to let them run down, but keep them topped up.
On the apple website, under the battery section, it recommends that they be run down to 0% once a month.
Doesn't this contradict what we know here about lithium based batteries?


From Apple
[h=3]Use iPhone Regularly[/h]For proper maintenance of a lithium-based battery, it's important to keep the electrons in it moving occasionally. Be sure to go through at least one charge cycle per month (charging the battery to 100% and then completely running it down).

I just charge mine daily, whatever it's at. I've had my phone for 3 years, and the battery is still fine. It runs down close to zero sometimes, but I don't worry about it.

The once a month rundown is to re-calibrate the battery meter. I do not believe this does any thing for the battery itself.

crizyal said:

The once a month rundown is to re-calibrate the battery meter. I do not believe this does any thing for the battery itself.

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Exactly.

Some lithium batteries do benefit from a "break in" process involving occasional full charge/discharge cycles, especially when new. A second reason for doing this is to calibrate the internal battery monitoring computer. Unless you run the battery through a full cycle it cannot measure the battery capacity, and therefore it can't give a good percent power remaining estimate based on power consumption. Since the performance of batteries changes over time, it is a good idea to re-run this calibration exercise periodically to keep the battery monitor up to date.

Makes sense.
Thanks
I also thought maybe the iphone may monitor the battery and fully discharged, may not truly be fully discharged.

It's ok to run liIons down, it's just not good to leave them there. Just make sure you charge the phone as soon as it powers down.

Launch Mini said:

Makes sense.
Thanks
I also thought maybe the iphone may monitor the battery and fully discharged, may not truly be fully discharged.

Click to expand...

I believe this to be correct. I have tested a few cell phones this way by running them down till it they were dead according to the display.. ("please re-charge phone now" ..or so so) and then removed and checked the battery. They were always around ~3.7v or a few hundredths higher. That's a very safe number so as to not harm the battery.

I normally would be against apple products. but the family made a unanimous decision to upgrade and, being in the family plan, personal opinions had to be set aside [mom wants facetime]. So, now that I have to learn to use it, I wonder if the Iphone 4S can be operated while plugged in constantly.

I ask because after reading about notoriously short runtimes I built a homebrew charger that runs off eneloops. Sacrificed an Apple charger to read its pinouts and configured my homemade so the iphone only draws 500ma out of it. Eneloops will charge the 4S for 5 hours and keeps the phone 100% no matter what I do, watch youtube on my lunch break, checking the weather, making phone calls, receiving phone calls... etc. It fits in my hip sack and so does my phone. :twothumbs:

Or just get one of these. It is both a battery backup that will power a USB-chargeable device, and a charger that will charge 4 AA NiMH cells off of a powered USB port.

Disclosure: I don't own one of these yet, but it seems like a great little item to carry around loaded with eneloops if you do a lot of traveling.

Battery Guy said:

Or just get one of these. It is both a battery backup that will power a USB-chargeable device, and a charger that will charge 4 AA NiMH cells off of a powered USB port.

Disclosure: I don't own one of these yet, but it seems like a great little item to carry around loaded with eneloops if you do a lot of traveling.

Click to expand...

Those look nice, but you have to make sure they specifically say they can charge iPhones. Apple devices look for a particular voltage on one of the data lines of the USB cable to decide how much current they can draw (e.g. 500 mA or 1000 mA) and if they don't recognize the voltage they won't charge. This only applies if you don't plug the phone into a proper USB port on a computer, which does of course work in the expected way.

Mr Happy said:

Those look nice, but you have to make sure they specifically say they can charge iPhones. Apple devices look for a particular voltage on one of the data lines of the USB cable to decide how much current they can draw (e.g. 500 mA or 1000 mA) and if they don't recognize the voltage they won't charge. This only applies if you don't plug the phone into a proper USB port on a computer, which does of course work in the expected way.

Click to expand...

Good point Mr. Happy. The specs on the Tekkeon site do indicate that this works with an iPhone, although the Amazon link I posted does not seem to provide this information.

Launch Mini said:

I also thought maybe the iphone may monitor the battery and fully discharged, may not truly be fully discharged.

Click to expand...

True. The iPhone stops responding before the battery is actually fully discharged. It just refuses to work until it's charged for ten minutes. It keeps enough of a reserve to protect your data for as long as a week or so.



Full Disclosure: I'm one of those independent consultants that help businesses make the best use of Apple products. Apple lists me and my company on their website, but my paychecks come from my clients.

Illum said:

I normally would be against apple products. but the family made a unanimous decision to upgrade and, being in the family plan, personal opinions had to be set aside [mom wants facetime]. So, now that I have to learn to use it, I wonder if the Iphone 4S can be operated while plugged in constantly.

I ask because after reading about notoriously short runtimes I built a homebrew charger that runs off eneloops. Sacrificed an Apple charger to read its pinouts and configured my homemade so the iphone only draws 500ma out of it. Eneloops will charge the 4S for 5 hours and keeps the phone 100% no matter what I do, watch youtube on my lunch break, checking the weather, making phone calls, receiving phone calls... etc. It fits in my hip sack and so does my phone. :twothumbs:

Click to expand...

If you protect your phones with a plastic protective skin , be careful when you ask for one for your new phone...... content deleted........ ......
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Illum said:

I normally would be against apple products. but the family made a unanimous decision to upgrade and, being in the family plan, personal opinions had to be set aside [mom wants facetime]. So, now that I have to learn to use it, I wonder if the Iphone 4S can be operated while plugged in constantly.

I ask because after reading about notoriously short runtimes I built a homebrew charger that runs off eneloops. Sacrificed an Apple charger to read its pinouts and configured my homemade so the iphone only draws 500ma out of it. Eneloops will charge the 4S for 5 hours and keeps the phone 100% no matter what I do, watch youtube on my lunch break, checking the weather, making phone calls, receiving phone calls... etc. It fits in my hip sack and so does my phone. :twothumbs:

Click to expand...

Eh? continuous charging? All of the cell phones that I own(ed) charge the battery to whatever the setting is for "full charge" and then shut off the charge as long as the charger plug remains plugged in. ie: Once the phone decides that the battery is charged, even if I remove/reinsert the charger plug for my Nokia E51, a message is displayed that the battery is fully charged and no more charging. My wife's Motorola cell phone actually displays a lower level of charge if she plugs it in in the evening and I look at it in the morning - no charging, no charge maintenance. Do Apple products automatically restart charging?

Otherwise the recommendation about recalibrating the battery meter is widespread among many products and fairly effective in my experience.

well its not continuously charging per se, but rather operate the phone essentially while its tethered, in such a way that the phone does not charge its battery but rather being powered by an external power source.

I have a mobile USB power pack like the one shown on the link, only mines a Lemar PPU2100B. The Iphone guages its charge rate by the voltage it reads off the data pins, so many USB batteries simply does not work.
The Official Apple 3G charger has the USB data Pin 2 set to 2.75V and Pin 3 set to 2.05V, the iphone draws 1A. With 4 resistors any USB battery can be made compatible, but the products in itself are not compatible.


Seeking for a prebuilt battery pack for the iphone I stumbled on a Griffin TuneJuice in Amazon. It uses 4AAAs... which first off isn't going to give 1A and runtime will be short even at 500ma, which was probably why the reviews were bad, but since it works I wanted to mod it to run 2xcr123As. It turns out both datapins were set to about 2V and charges at the rate near that off of my computer [500ma max per port], so I went ahead and built my own charger using spare parts.

Now, fortunately I didn't destroy my iphone in the experiments, but ymmv.

Griffin came out with a new 3xAA model, 5 V @ 850 mA

http://store.griffintechnology.com/iphone/tunejuice-universal

My iPhone 4 really doesn't have heavy battery drain. It will last a day or two of normal use between charges. The only thing that really runs the battery down is playing Angry Birds for a couple of hours.

Also, as with all lithium ion batteries it is a bad idea to keep the battery at 100% as that will shorten the battery life. The optimum strategy is to keep the battery between 20% and 80% as much as possible.

Any "news" with regard to IPhone 4S batteries ? On the back label it just says Li Ion but some people believe it is a Li Ion polymer and swear it is bad for the battery to drain it below 20% is this so ?

I would assume that if apple says it is OK to run the battery down completely there is no problem and that the battery has a self protect device that will shut it off before it is too late for ruin.

There isn't really any difference between lithium ion and lithium polymer. Just a slight variation in how they are constructed, that's all.

As far as my iPhone is concerned the phone displays a red "low battery" warning at 20% and a "very low battery" warning at 15%. I usually charge it when this happens as I don't want the phone to die on me unexpectedly. I have only once run the battery down until the phone switched off, just as an experiment, but normally I don't let this happen.

There is of course a battery management system to prevent the battery being damaged. Any worries about fully draining the battery are misplaced, although fully draining the battery on a regular basis may shorten the battery life a bit (see my comments above about keeping the battery between 20% and 80%).

All thin, flat, lithium batteries like the ones found in phones are lithium polymer. This is inevitable, since lithium polymer is the technology that allows thin flat phone batteries to be made.