July 25th, 2007
Calculate Your iPhone’s Battery Lifespan
By Michael Santo
Executive Editor, RealTechNews
One of the negatives of the iPhone, which many have complained about, is the lack of a user-replaceable battery. And let’s not talk about the great battery replacement plan. PC Magazine has gone through the trouble of developing an online calculator that will predict when your precious iPhone’s battery will bite the dust. You enter the date of purchase, and it pops up the result, including a countdown timer.
Our methods for finding a date were simple: we used a fully-charged iPhone the way one typically would. That meant four phone calls, between three and ten minutes each; listening to the iPod on a 40-minute commute to and from work; checking Google Maps at one point when we were lost on the way to a meeting; and checking e-mail a whole bunch of times over both Wi-Fi and EDGE. The phone lasted about 30 hours. Counting in the four hours or so it takes to trickle-charge over a USB port, the iPhone gets about 34 hours, or roughly 1.5 days, per charge.
Apple says that after 400 charges, the phone will hold 80% of a charge. Alas, they wouldn’t tell us any more than that. (When we inquired, they skirted the issue.) Regardless, we’ll push it a bit beyond 400 charges and say that you’ll really feel like replacing your battery at 450 charges. Thus, 450 x 1.5 = 675 days. Source: PC Magazine
We Say: Naturally (especially if you look at their disclaimer), this is mostly tongue-in-cheek. However, I’d make a couple of adjustments … for example, based on how well the iPod batteries seemed to hold up, I’d wonder about the 400 charge claim. 
Yeah, yeah, I know they’ve made improvements.
Also, my understanding is you don’t want to let Li-ion batteries drain competely … and most people would just plug it in at the end of the day rather than wait for the extra half-day. So assuming this electronic back-of-the-envelope calculation is even close to correct, you’d get 450 days or less than 1 1/2 years.
Or, you could just wait and see what happens …
Dman says:
Interesting article, but one point is incorrect. You definitely DO want to drain lithium ion batteries all the way before recharging, otherwise they develop a memory. Say you charge up a lot when you have 20% charge left. Eventually that 20% point becomes your new zero charge remaining point. I believe this is why some folks are already having battery issues with I-phones.
Nickel metal hydride batteries don’t exhibit this memory effect, and thats why they use them on Hybrid vehicles. Lithium ion holds more charge by weight, so that is why it is often used for cell phones and laptops.
Lithium ion= drain completely before recharge.
Nickel metal hydride= charge em whenever you want.
July 26th, 2007 at 8:01 am
Lanie says:
Dman,
You are WAY off on this. Lithium-ion batteris DON’T have a memory.
They were designed to be topped off.
August 8th, 2007 at 11:46 am
Jeb says:
Yeah Dman,
You’ve COMPLETELY got it backwards. Li-Ion Batt. DONT have the memory effect. It’s the NiCd batt. that do that.
October 24th, 2008 at 9:39 pm