iPad mini What really is the point in draining battery to 0 percent once a month

srkmish

macrumors regular
Original poster
Feb 10, 2013
216
0
Hi friends,

As far as I have researched on the Internet, today's lithium batteries pretty much take care of themselves and a research has been done which shows people who charge their mobiles more often ,their batteries last longer than those who frequently drain it.

can you guys post ur experience of battery optimisation techniques and is it really necessary to drain it to 0 once a month as recommended by apple
 

Menel

macrumors 603
Aug 4, 2011
6,200
1,050
It's for calibrating the percentage meter.

Repeated shallow discharge/charge cycles can cause miscalibration. e.g. reporting 50% when you really have 80%.

Once ever month or 3. Don't do it intentionally more than that.
 

Mrbobb

macrumors 601
Aug 27, 2012
4,989
192
can you guys post ur experience of battery optimisation techniques and is it really necessary to drain it to 0 once a month as recommended by apple
Mine rarely goes down to single digit so I don't need any precision, hence I forgo the suggested monthly calibration. It feels so great not to have to babysit these gadgets.
 

zorinlynx

macrumors 603
May 31, 2007
5,643
6,720
Florida, USA
Lithium batteries last longer when not kept at a full state of charge all the time.

Best practice with an iPad, if you have access to a charger every night, is to get it down to about 30-40%, then charge it. Charging it every night will cause the battery to spend more of its lifetime at a full state of charge, which causes faster gradual chemical breakdown.

Note the recommended storage guidelines for Lithium batteries: 50-60% state of charge, cold location.
 

iamthekiller

macrumors 6502a
Feb 3, 2010
635
1
There is no truth to this stupid belief. It's not necessary or beneficial with today's modern batteries.
 

charlituna

macrumors G3
Jun 11, 2008
9,629
805
Los Angeles, CA
Hi friends,

As far as I have researched on the Internet, today's lithium batteries pretty much take care of themselves and a research has been done which shows people who charge their mobiles more often ,their batteries last longer than those who frequently drain it.
That's not really true. Lithium batteries have a set cycle count life and it's the same whether you zero out every time or not. The only difference is that the math is dealing in partial cycles not full ones.

The draining it out is more for the software than the battery. Particularly with iOS devices since the same software is running batteries of very different sizes. The meter software can become corrupted just like any other software in the system so a full drain to shut off periodically helps to keep the meter correct so it doesn't report you have battery falsely when it is in fact drained.

All of this though is secondary to the issues of never running the battery (ie keeping it on the charger all the time) or having it drain out and now charging it for ages (which means even the trickle charge drains out eventually). Those two things will kill your battery more than how often you charge it
 

hchung

macrumors 6502a
Oct 2, 2008
689
0
That's not really true. Lithium batteries have a set cycle count life and it's the same whether you zero out every time or not. The only difference is that the math is dealing in partial cycles not full ones.

The draining it out is more for the software than the battery. Particularly with iOS devices since the same software is running batteries of very different sizes. The meter software can become corrupted just like any other software in the system so a full drain to shut off periodically helps to keep the meter correct so it doesn't report you have battery falsely when it is in fact drained.

All of this though is secondary to the issues of never running the battery (ie keeping it on the charger all the time) or having it drain out and now charging it for ages (which means even the trickle charge drains out eventually). Those two things will kill your battery more than how often you charge it
Properly designed lithium battery chargers don't actually keep trickle charging the battery unnecessarily. Many of them don't even turn on the current flow if the battery is between 95% to 100%, so the issue you mentioned at the end shouldn't happen. (Some will have tricks for refilling them at the end and it's all right, but leaving a lithium battery on the charger indefinitely should never be a problem on a proper charge)

Partial cycles arn't uniform across charge levels.

I recall if you charge from 0 to 10%, you apply more wear and tear to the battery than if you charge from 60%-70% even though they're both 10% of a cycle.

Also, past 4.0 volts, it's best to charge at a slower rate to keep the heat down because then you'd also have more wear and tear than the middle. Do that and you'll keep the upper end wear and tear to a minimum.

Ideally, it's best to keep your battery in the middle 1/3rd but that's not really feasible. Next best is to always keep it as full as possible. Worst is to drain often and then charge it back up entirely frequently.

(I had to design a lithium polymer battery charger a while back for a side project. Got a bunch of research done, but turned out it was much more worth it to use off the shelf components than to actually implement our own so never finished it.)

With that said, I only deliberately do a full drain calibration cycle on my device when I first get it. And always try to leave it on the charger if I can. Oh, and if I have a choice, always the slowest charger I can get if I have the time.
This calibration thing? I'll do it again in 2 years if I still use the device. Certainly not every month.