4.0.1 Battery Life

modular speaks the truth.

Heat, and overcharge are the worst enemies to properly voltage-cutoff Li-ions. But as the iPhone's cutoff prevents it from discharging into the danger zone, it's also protected from overcharge.

It should be noted that technically, you do not need to deep-discharge so that the voltage drops into the "danger zone" in order to affect battery capacity. For example, a 12v battery regularly discharged to a nominal 11.0V (and most voltage cutoffs for 12V will happen at 9-10V) will lose capacity greater than a battery not discharged past its load plateau of 12-13v.

This doesn't mean you'll lose half your battery capacity in one year if you always let your phone run to auto-shutoff, but your battery health will be better maintained if you don't do that all the time.

Lawrence Finch wrote:

modular747 wrote:
Heat is the main culprit in limiting lithium ion lifetime - a major reason limiting their use in electric and hybrid cars.

You mean like limiting their use in the Tesla Roadster, the 250 mile range electric car powered by Lithium ion technology that can do 0-60 in 3 seconds? Doesn't sound like much of a limitation.

I don't follow where use in the Tesla or a fast 0-60 = heat. With proper heat shielding and ventilation, the battery packs themselves need not be exposed to too much heat in proper application. With that said, wild temperature swings and operations in the margins of extreme climate (cold + heat) is in fact one of the main factors as to why electric cars and PHEVs are taking so long to be developed and get to market. The battery chemistries are so new that nobody really knows how long they'll last or in what fashion they'll degrade in the lifetime of an average automobile, especially when you take into account the environmental variables in which cars need to reliably operate.

You mean like limiting their use in the Tesla Roadster, the 250 mile range electric car powered by Lithium ion technology that can do 0-60 in 3 seconds? Doesn't sound like much of a limitation.

The Tesla is a >$100K car that pumps coolant to the battery pack and is rated for only 70% capacity after 5 years. (Don't worry, a replacement battery pack is only $36K!!).

The limitation is cost to make it function reliably. Don't hold your breath for an affordable Li-ions Prius...

Message was edited by: modular747

modular747 wrote:
The limitation is cost to make it function reliably. Don't hold your breath for an affordable Li-ions Prius...

The 2012 has been announced as Li-ion.

Since you mention the Prius, which is NiMH, the charging circuits in it don't let the state of charge go below 40% or above 65% in normal driving. On long downhill runs it lets it get as high as 80% before it engages engine and friction braking instead of regenerative braking. We don't know the normal life of the Prius battery because too few have failed to produce valid statistics (<1% according to Toyota). But in the Prius discussion group I follow, with 16,000 owners, many batteries are still working after 10 years and over 200,000 miles (the record is 320,000 miles when the 2001 model threw battery codes indicating an out-of-spec cell). Mine is only 7 years old and 80,000 miles, so I expect a lot more out of it (the warranty is 100,000 miles/10 years, except in California, where it is 150,000 miles).

Back to the iPhone, Apple says there is no harm in recharging as often as you like: http://www.apple.com/batteries/

+A charge cycle means using all of the battery’s power, but that doesn’t necessarily mean a single charge. For instance, you could listen to your iPod for a few hours one day, using half its power, and then recharge it fully. If you did the same thing the next day, it would count as one charge cycle, not two, so you may take several days to complete a cycle. Each time you complete a charge cycle, it diminishes battery capacity slightly, but you can put notebook, iPod, and iPhone batteries through many charge cycles before they will only hold 80% of original battery capacity. As with other rechargeable batteries, you may eventually need to replace your battery.+

d5kenn,

I know this is off topic. Sorry but this is the only way I could get in touch with you.

But I saw your post on your iMac a couple of months ago. The thread has since been archived. Would appreciate the email you spoke about, would love to see what was written.

bennykee@hotmail.com

Thanks!!!

Benny

Hi all,

It's been a while since I last posted in this thread. After not getting anywhere with the battery life issue, I thought I'd wait for iOS 4.1. Unfortunately, that didn't help, and my battery was still draining while the phone was in standby.

I didn't get the time to charge to 100% and unplug before I went to bed last night. However, I was playing around with Exchange accounts, removing them and re-adding them, and as part of this, I did a network settings reset. The significance of this: all of my previously remembered wireless networks were lost. When I got to work the next day, having taken my phone off charge that morning, I'd completely forgotten that previously remembered wireless networks were lost, and it was only much later in the day that I noticed I wasn't on wi-fi. At the same time, my battery was still at a very good level - much like before all these draining problems started.

I have continued for a number of days now with wi-fi networks not connected, and battery life is still excellent - exactly how I remember.

Tomorrow, I'll re-add my home and work wireless networks and see how things go. At the moment, it looks to me that, strangely, wi-fi is the problem.

SR iMac,

i have the same problem as well but that's not the only problem because the other one is the signal, sometimes you cant text or call or receive either of those at random times. My solution is i restored my iphone 4, 6 times then now the battery is much better but the signal issue is still worst.