How to use your iPhone plugged in without cycling the battery

Discussion in 'iPhone' started by now i see it, Apr 13, 2016.

  1. now i see it, Apr 13, 2016
    Last edited: Jul 1, 2016

    now i see it macrumors 68030

    Jan 2, 2002

    [This has been edited extensively since the original post to more clearly illustrate the following.]

    A USB extension cable will lower the current flowing into the iphone battery due to the increased resistance of the cable. The current is reduced, not the voltage.

    The length of the cable determines what the charge rate will be. The longer the cable, the less current will flow. This allows much gentler trickle charging when using the phone while plugged in and when not in a hurry to charge. Lower charging rates keep the battery cooler while charging and put less stress on it.

    A 5ft USB extension cable will effectively cut the charge rate of the standard iPhone charger (3.55 watts) by 65% to 1.26 watt. Two of them (10 ft) will trickle charge the battery at 10% of the normal rate at 0.34 watts.

    What this equates to is that an iPhone, when plugged in, can be trickle charged at a low enough rate with a suitable length of USB cable, that the number of micro charge cycles can be reduced due to the lengthened charge times... It's also a lot easier on the battery. This can be useful when using the iPhone always plugged in and keeping the battery capacity below 100%.

    Using an USB extension cable is not recommend if the goal is to charge the phone to 100% as quickly as possible.

    To keep the charge indicator calibrated, the battery still should be discharged once a month to below 20%, then fully charged to 100% while using the standard iPhone charger and cable.


    Standard iPhone wall charger alone:

    with 5 ft USB cable

    with two 5 ft USB cables connected together.
  2. electronicsguy macrumors 6502a


    Oct 12, 2015
    Pune, India
    FYI: this is rubbish. You are infact hurting your battery more. Read this:

    You're creating a sub-normal voltage at the phone end. the trickle charge ends up not charging much at all and you have more power loss. The link gives detailed numbers.
  3. cynics macrumors G4

    Jan 8, 2012
    Waste of time, 'battery cycles' is just a term used for packaging overall battery usage. You are still using the battery and the chemical reaction is still happening and the battery is still wearing out.

    Besides you can stop by an Apple Store and have the battery replaced if you need it one day. You made a mobile phone a home phone..such a waste.
  4. now i see it thread starter macrumors 68030

    Jan 2, 2002
    The link posted above proves my point exactly. Longer cables slow down the charge rate. That's the whole point. Trickle charging is better for all batteries, including Lithium iron phosphate batteries used in iPhone.

    The Apple charger is a compromise in fast charge times vs battery stress. They can't sell a trickle charger with the phone that takes twice as long to charge the battery, so they don't.

    What most people want is to charge the battery as fast as possible.
    For those of us who use our phones all day next to a power source, trickle charging is the best choice for the battery. It keeps it cooler and puts less stress on the battery. USB extension cables provide that means.
  5. timeconsumer macrumors 68000


    Aug 1, 2008
    I feel like you're overcomplicating a simple task. Whether you're charging the battery faster or slower you're still putting charge cycles on the battery. Just use the included charger/cable and plug your phone in when you need to charge.
  6. Newtons Apple macrumors Core

    Newtons Apple

    Mar 12, 2014
    Jacksonville, Florida

    All of the above is BS.

    Just use your phone and charge it when you sleep, repeat until you get a new phone.

    Someone needs to find a girlfriend and then you will not be worrying about stuff like this.
  7. joeblow7777 macrumors 603

    Sep 7, 2010
    My response to this whole thread is: Why?
  8. Retops macrumors regular

    Feb 10, 2008

    This is valid advice. Don't worry about the cycles and just enjoy the phone. Most people will never wear out the battery.
  9. BigMcGuire, Jul 4, 2016
    Last edited: Jul 4, 2016

    BigMcGuire Contributor


    Jan 10, 2012
    Interesting post. Because of my OCD I will try to keep this short (Hi, my name is Paul and I have a battery OCD) (Edit: I failed). I too have 6ft chinese iPhone cables that charge the phone super slow. Since my phone lives near my desk at work (programmer) it can be plugged in all day. Battery University does mention how to prolong the life by not rapidly charging it (mostly due to heat). But what I've been reading, batteries can take a lot more punishment than we thought - all those rapid charged batteries are having no noticeable detriment to them.

    Check out: - Most of the information comes from Battery University

    Unlike a laptop, the iPhone seems to draw its power absolutely from the battery - meaning, even if it were plugged in and the battery removed, I think it would not power on (like a laptop). This has been the case for every phone I've owned. So there's no way to reduce cycle counts on a battery without ... not using the phone. Unlike my Macbook Air which, after a year of use only has 41 charge cycles cuz it remains plugged in most of the time (using AC).

    I've fallen heavily in the OCD battery crowd in the past and got to the point where I was running my phone in Airplane Mode to reduce charge cycles. Posters here like @Newtons Apple and @I7guy helped me see I was being insane. Using my 6+ normally for 1.5 years didn't even top 300 charge cycles and still had 97% battery life left before I sold it to Apple. And for a very nominal fee, the battery can be replaced, and will be replaced by Apple if under 80% before 500 cycles (AppleCare+?). They (wise posters above) have a very good point - even if you used the phone heavily, battery will most likely outlast the phone.

    That said, if you want to help your phone's battery? OCD - Keep it between 40-80% and charge slow (iphone charger vs ipad). But I've come to the conclusion it's difficult to enjoy using my phone and do this. Not so OCD: Keep it out of the sun, try not to drain it below 20% if you can help it, and enjoy it! Get an iPad (it has a 1000 cycles to 80%) and use that while your phone sits unused not consuming cycles. :p

    @now i see it - I wonder how much charging at a lower rate actually helps. I agree it helps but is the benefit noticed in 2 years? I've always charged with 3.8a+ chargers and all my iPhones have been sold with 95%+ life left after 2 years.

    So, I have a few Anker batteries (13,000 mAh and 26,800 mAh) to charge my iPad and iPhone all the time - then use a 21 watt solar panel to charge them up (The 13,000 mAh is charging right now in my back yard (battery safely in the shade with a 6 ft cable)).

    Yes, I have a battery OCD but it's a lot healthier than it used to be. <cough> I could talk about batteries all day. lol. But these guys are right, if it's interfering with the enjoyment of the phone, it's not necessary - battery can be used normally - my wife's iPhone gets "abused" much more than mine and only has a few % points under mine (coconutBattery) usually and she runs hers to 0% regularly.

    Edit: Wow that started out a paragraph long. My apologies.
  10. Newtons Apple macrumors Core

    Newtons Apple

    Mar 12, 2014
    Jacksonville, Florida
    If the above helps people with battery OCD, then it served it purpose.
  11. I7guy macrumors P6


    Nov 30, 2013
    Gotta be in it to win it
    What your post really points to, is that we all want to try within reason, not to abuse the battery, in the face of a lot of different internet opinions of what is the best way for longevity.

    You made some really good points, especially about your wife's battery. And I like the solar charging, that's way cool.

    From what I can gather about the worst abuse is deep discharge, even though battery circuits don't let the phone do that, keeping that charges reasonable is about the best way to keep a battery healthy given the current state of battery technology.

    So thumbs up for a very well-reasoned post.

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