Best practice for charging iPods and iPads in the car?
July 13, 2013 2:33 PM   Subscribe

Everyone seems to have a different opinion about best practice for charging iPads and iPods in the car. Two guys at best buy just told me exactly opposite things! Looking for people who either actually know what they're talking about or who have experience on the matter. Specific questions inside.

I have heard two conflicting things from best buy employees and from forums online with respect to the following:.

Is it ok to charge an iPod with an ipad charger in the car? Some say that it's fine because the iPod regulates it's energy intake and stops charging when it reaches 100%. Others say that it is not a good idea because the ipad charger produces more amps. This will burn out the iPod. (Conversely the iPod charger will not charge the ipad at all because it doesn't produce enough juice.) Which is it?

Does anyone really know how these batteries actually work? No one seems to agree about any of this stuff (or other things like charging all night, unplugging in the middle of a charge, etc.). It seems weird. Big road trip coming up and I want to get it right without ringing any of our gadgets. Thanks.
posted by crapples to Technology (18 answers total) 3 users marked this as a favorite
 
It will be fine. The volts are all that matter.
posted by unSane at 2:38 PM on July 13, 2013


Others say that it is not a good idea because the ipad charger produces more amps.

These guys don't know what they're talking about. A decent way of putting it would be to say that amps are drawn by the device being charged, not pushed into the device by the charger. The charger controls the *voltage*, and it's important that the voltage be correct. An ipad charger might be *able* to provide more amperage if the device plugged into it "asks" for it, but it's not going to force extra amperage through the device.
posted by jon1270 at 2:39 PM on July 13, 2013 [7 favorites]


I have taken many multi-day road trips with iPods, iPhones, and iPads in several different cars,using the same USB cord. I have never thought twice about charging them from the car and have never had a hint of a problem.
posted by The Deej at 2:39 PM on July 13, 2013


It works fine. That the Ipod will burn out is a bizarre urban myth. It is true that a regular Ipod charging cord won't charge your Ipad as fast as as the Ipad cord will, but it will get there eventually.
posted by bearwife at 2:40 PM on July 13, 2013


Others say that it is not a good idea because the ipad charger produces more amps. This will burn out the iPod.

Pardon my french, but this person is a fucking moron. This is about as possible as your microwave irradiating your food and making you sick. Even apple notes that the ipad charger is good for any ipod/iphone. It'll be fine, and in fact all the iphones since the 4 actually charge faster with the ipad charger(they don't advertise this, but it's true).

(Conversely the iPod charger will not charge the ipad at all because it doesn't produce enough juice.)

This can actually be true. You'll get the "Not charging" notification. You need at the very least a real, 1 amp iphone charger to charge an ipad.. and that'll do it VERY slowly.

The solution here is to get an ipad charger and use it for everything. There are also cheap(like $5!) combo ipad+iphone chargers that put out the higher amperage for charging an ipad from one port, but the lower iphone amperage from the other. Look for one of those. Problem solved.

Does anyone really know how these batteries actually work? No one seems to agree about any of this stuff (or other things like charging all night, unplugging in the middle of a charge, etc.)

Leaving it plugged in indefinitely isn't a problem unless you do it for something like a year continuously. Don't worry about leaving it plugged in all night. Inversely, don't worry about not plugging it in for some minimum period of time. The only way you can hurt the battery is by leaving it completely drained for months, or leaving it plugged in for months. Anything else doesn't matter.

There's not a lot to worry about here. Any charger with a USB port will probably charge an iphone(and none will hurt it), and anything that says "ipad charger" will charge both without causing any issues.

The only thing i'll note there is that some cheap wall chargers output "dirty" power and cause some issues with the touch screens. This probably can't hurt the devices, but is annoying. No car chargers i've seen cause any problems since they're just converting 12v(+/- a bit) to 5v. And the one i use for my iphone and ipad is literally so cheap the case fell apart. Works perfectly for a couple years now.
posted by emptythought at 2:43 PM on July 13, 2013 [3 favorites]


I have used iPad, iPod, iPhone, etc. cables interchangeably for years with no ill effects. As long as the plug ends are compatible, you're good. If there was a significant problem with this, Apple wouldn't have designed the cables to look identical, and there would be big FOR IPAD USE ONLY warnings all over everything.
posted by Sara C. at 2:43 PM on July 13, 2013


I have taken many multi-day road trips with iPods, iPhones, and iPads in several different cars,using the same USB cord.

Yeah, insofar as the "charger" we're talking about is just the USB cable, they're all the same. There's no functional difference between the cables that come with these devices, except for the newest ones (iPhone 5) with a totally different connector.

You know how you can screw a 150 watt bulb or a 40 watt bulb into the same socket, on the same electrical circuit, and each takes exactly as much current as it needs? This is the same.
posted by jon1270 at 2:44 PM on July 13, 2013


The lithium ion batteries inside iPods and other modern electronics literally explode if you charge them incorrectly. In practice this means every device has to have proper charge regulating circuitry built into the device, not the charger / power source.
posted by ryanrs at 2:44 PM on July 13, 2013 [1 favorite]


Standard USB ports will provide only 1/2 amp (500 milliAmps.) An iPad charger provides 2 Amps (2000 mA). You can run an iPad on a standard charger adapter (cigarette adapter) but it won't generally charge. You can charge anything with an iPad charger. There is no risk of damage either way.

Best Buy does not employ engineers, generally. They recruit from the same pool as does Radio Shack. Tech KNOWLEDGE is less important than showing up, sounding informed, etc.

They do the best they can, but it's usually a better idea to do your research, then shop than to ask these folks. Really, it's not their fault though it is tempting to think they are possessed of all the right answers because they dwell amongst all that hardware.

If it helps, consider that few people have working at Best Buy as their ultimate career goal. I have a growing empathy for them, and for their brethren/sistren at Radio Shack.
posted by FauxScot at 2:52 PM on July 13, 2013


2.1 A car adapters (for iPads and other tablets) are quite cheap, under ten dollars. Here's a single plug one, this is a double plug. Both will allow your devices to charge at full speed.
posted by bonehead at 3:04 PM on July 13, 2013


Everyone in here is right, and those Best Buy guys are...insane, but another thing that can be confusing about the iPad situation is this:

1) The iPad needs a decent amount of current to run at all.
2) The iPad will make do with whatever trickle of current it can get over USB to charge, but will take longer, won't necessarily run, etc.
3) Normal USB ports I think generally don't actually supply this much current.
4) The iPad, when deprived of current, will say "Not Charging" in the little status bar at the top where the battery indicator is.

So, what's slightly confusing about this is that sometimes, when plugged into a marginal power source (say, an ordinary laptop's USB port) the iPad *is* charging, but every time you look at the screen, it says, "Not Charging". It's because every time you fire up the screen, the current draw exceeds what the USB port can supply, and so the iPad stops charging. But if you put the smart cover on or hit the sleep button, the iPad goes back to charging. It's kind of like a "how do you know the light goes off when you close the refrigerator door" situation.

Apple's solution to this is to make some of it's USB ports able to supply more current than the USB spec strictly requires so that you don't see this warning if you plug the iPad into your MacBook Pro. Many powered USB hubs will do the same thing. There are also devices that will gang two USB ports together for power since technically, each one is supposed to be able to supply 500mA (I think). Shitty laptops and hubs may ignore this though and have however much current total available for the whole bus, and whoever draws it draws it.

Here's another useful thing to know about Apple chargers: All these USB-ish gadgets pretty much charge at 5V. Watts = Volts * Amps. All those identical-looking white cube power chargers have their wattage rating on them, presumably because the law requires it, so you can figure out how many amps they can supply by dividing the number next to the W by 5. It doesn't really matter, except with iPads, because they take forever to charge at 1A (the little 5W iPhone chargers), but it's good to know if you forget which one is which and you want to charge an iPad.
posted by jeb at 3:51 PM on July 13, 2013 [2 favorites]


My first-generation iPod Touch has spent years plugged into my car, continuously. It's fine. It hasn't exploded, and the battery seems to still hold a charge just fine.

My iPod Mini has gone through a similar experience, though, and its battery can't hold a charge at all. But that's probably because it's almost a decade old.
posted by Maladroid at 3:55 PM on July 13, 2013


Small, intriguing data point: I recently purchased an automotive USB charger that generates up to 2 amps of 5 volt power, because my car's bulit-in USB couldn't always keep up with my iPhone 5. It works fine with my iPad 2 as well. However, a friend tried to charge her Motorola phone via USB and her phone immediately popped up a warning that the charger was not the official one and might damage the phone, and so the phone would not be charging. When I switched it to the car's bulit-in USB, her phone charged without incident or warning.
posted by davejay at 4:40 PM on July 13, 2013


The charger controls the *voltage*, and it's important that the voltage be correct.

Not entirely true -- in the case of lithium polymer batteries in your iDevice, the first phase of the charge cycle involves the charging circuitry providing a constant current to the battery as the voltage increases from the discharged state (generally somewhere between 3.3V and 3.7V per cell) to the nominal lithium ion chemistry of 4.2V per cell. At that point, the charging circuitry enters a constant voltage regime as the current slowly drops to almost zero. It is important for the charging circuitry to properly limit the current in the constant current phase, or your battery will overheat and catch fire.

However, as ryanrs mentioned, this charging circuitry is not actually in your power adapter -- it's inside your iDevice, connected to your battery. It's going to make sure your battery does not get too much current during the constant current phase, even if the power adapter is capable of providing more current than necessary.
posted by Behemoth at 6:16 PM on July 13, 2013


I managed a fleet of iPads and iPods (iPhones actually).

On 30 pin connectors I buy anything and have never had a problem. With the lightning connectors I buy Apple and still have never had a problem.

I would ignore these people.
posted by cjorgensen at 6:43 PM on July 13, 2013


Thanks so much for all of the great responses. The complete consensus on this topic among the people posting gives me total confidence that the things I've read and heard are just not true. This is great news to me. I just ordered an ipad car charger on amazon and will use it to charge all of our devices on our trip. Thanks again.
posted by crapples at 6:29 AM on July 14, 2013


Does anyone really know how these batteries actually work? No one seems to agree about any of this stuff (or other things like charging all night, unplugging in the middle of a charge, etc.).

Every battery chemistry has its own set of rules, and people tend to remember one set or another and apply it to all rechargeable batteries. (e.g., you find a lot of places on the net applying nickel-cadmium folklore to lithium-ion batteries.) But sometimes the best thing for one battery chemistry is the absolute worst thing for another.

All the iDevices, as far as I know, use lithium-polymer batteries (which are a kind of lithium-ion battery). IIRC, the main thing that hurts lithium-ion batteries is temperature; avoid letting them get too hot, especially when charging. If you're storing one for a long time, manufacturers seem to suggest storing them at 50% charge, because full charge + heat is even more stressful for the battery. If you're using them, though, I'd suggest just keeping them charged all the time, mostly for convenience's sake; the circuitry in the iDevice is smart enough to stop charging the battery when it's full. AIUI, if the battery's not hot, then additional charge-discharge cycles will wear it out faster than the degradation from being fully charged will.
posted by hattifattener at 11:47 AM on July 14, 2013


If you go into "airplane mode" it shuts off the wifi and bluetooth, leading to faster charging times. Of course, turning the device off completely would probably be even better. I read this on Lifehacker, so we're downstream from the horses, but it makes sense.
posted by craniac at 3:00 AM on September 21, 2013


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