Do car chargers kill your iPhone battery?

Discussion in 'iPhone Cases and Accessories' started by nikeplayer222, Jan 24, 2008.

  1. nikeplayer222

    nikeplayer222 Member
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    I purchased the first edition ipod nano about 2 or 3 years ago, whenever it first came out. Soon after, i bought a itrip car charger. The salesman at the store told me that i should be careful with car chargers because it ruins the ipods battery. It sends pulse charges instead of a consistent charge like from a wall charger. Well after a couple years, i can tell my ipod battery has been seriously affected. I left it in a decent amount of time with a full charge. Will my iPhone batter be ok as long as i take it out after a full charge?
     
  2. IphoneTony

    IphoneTony Zealot
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    I heard 2 sides to this ....some say yes some say no... let me see if I can find the info and ill pm it to you
     
  3. JoeT

    JoeT Member
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    Actually, that would be the other way 'round.

    Your can runs off of DC - Direct Current, which is as it's name implies, direct.

    Your home runs off of AC - Alernating Current - which alternates direction and phase in a cycle based off a sine wave.


    When you plug in a car charger, it (generally speaking) drops the voltage down from the 12v your car provides to the 5v (or whatever) that your device requires. It does this with a voltage regulator or step-down transformer. The resultant waveform is smooth. Imagine this like using your thumb to "step down" the flow from a garden hose. Not much different, just a lower voltage.

    When you plug in your AC adapter at home, the forward biased AC is pulled from each phase and rectified into a DC current. Yeah, I know. Try to imagine a wave crashing in to a beach and then flowing back out. Now imagine that we grab water from the wave as it flows forward but NEVER as it flows backward. That would leave a time period in which we collect no water. Now imagine that we have two waves, each crashing exactly when the other is receding, and that we grab from each wave as it comes in. That would give us a flow of water that has peaks and valleys - never a steady stream, but made up of spurts, if you will. This is what you are getting in a rectified DC current. That output is then smoothed out to level it a bit.

    That being said, this really should NOT affect most modern battery chemistries much - in fact, most smart chargers (which are designed specifically to maintain a battery in top condition) will pulse their output in their trickle-charge stage to avoid overcharging the battery (charge, test, charge, test).


    That being said, there *are* charging behaviors that can shorten a battery's life, and they vary by battery chemistry:


    1. Alkalines - well, using them. Non-rechargeable. :)

    2. NiCd - Nickel Cadmium - suffer from a memory effect when recharged too frequently after short periods of usage.

    3. NiMH - Nickel-Metal Hydride - No memory issue, but don't care for being overcharged. Can be ruined by constant charging. Note that smart chargers will detect this and shut off the charging cycle, so it really depends on your charger. Car chargers and common "wall-wart" chargers are NOT smart.

    4. Li-Ion - Lithium Ion - very hardy batteries, but don't like to be overcharged or seriously discharged.

    5. Li-Polymer - Lithium Polymer - pretty much the same as Li-Ion.


    As far as the iPod/iPhone, it contains circuitry that prevents overcharging even though the chargers do not. And since the Lithium composition likes to be recharged as often as possible, there's never a reason not to charge it.

    If you use a brand-name charger made for the iPod/iPhone and experience a problem, I would opine that you have a bad battery to begin with.


    If you still want to read more: http://en.wikipedia.org/wiki/Battery_charger
     
  4. wrhutch

    wrhutch Member
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    JoeT, Very well written and accurate but I'd like to add one thing. I have witnessed problems when an older firewire style chargers are used to charge or power the iPhone and any of the new generation iPods. These style of chargers use 12V DC instead of the 5V DC that the USB cable supplies.
     
  5. JoeT

    JoeT Member
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    Well, the cable should step it down to 5v if it is designed to power an iPhone/iPod. If it's some sort of direct cable, then yeah, smoke and a lighter wallet are in your future.

    Easy thing to do is to make sure that your power accessory says it works with the device you want to use it with - especially if my above post was in any way confusing. :)
     
  6. nikeplayer222

    nikeplayer222 Member
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    yes, it was made for the ipod. Griffen makes it if i recall correctly. I was just making sure because i'm more anal about my iPhone then i was with my ipod. Thanks for the quick answer :laugh2:
     
  7. JoeT

    JoeT Member
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    My pleasure. Also, keep in mind that many iPod accessory manufacturers are posting charts on their websites that show iPhone comparability for their products. Never hurts to check.
     
  8. wrhutch

    wrhutch Member
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    Many of the older (1st Gen) 30 pin connecter chargers were not stepped down to 5V. I've opened three car chargers (different brands) and all three simply had a series diode and fuse without regulation. This means that the possiblity exists for there to be in the neighbor hood of around 13.1V (13.8V - 0.7V Diode drop) approximately. I traced the wires through to the 30 pin connector and verified that they connected to the Firewire connections on the 30 pin connector pinout.

    My recommendation for car chargers is to look for a charger that has a standard USB port on it. This way you know that it's 5V.
     
  9. dorrien12

    dorrien12 Member
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    So for the iPhone 4s, is it good to let it drain until it shuts off and do a full charge or no?

    If so, how often should I do it?
     
  10. MuddyPaws

    MuddyPaws Zealot

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    I guess it's worth noting that when the car is running you are also getting a rectified DC current as you are when you plug into the wall at home.
     

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