Home Forums Peripherals & Multimedia iTunes, iPhone, iPod, iPad, Apple TV Using Hub To Charge iPhone & iPad, Safe?

I was given an externally powered IOGEAR 7port hub (USB 2). My old iMac is USB 2 and AFAIK, the hub works as designed, well, at least for thumb drives.

But I have no way of easily measuring the hubs output power. Thus to the question: Is it ok to charge my iPhone & iPad via the hub, or is it preferable I only use my Mac or the AC charger?

I have a Belkin F5U701 7 port hub and, like you, do not know how many volts it delivers. However I do find that it will not charge my iPod Nano so I have simply got into the habit of charging with my AC charger. In the absence of hard data (re: power) that seemed the best approach.

As stated above, most USB hubs do not provide sufficient power to charge an iDevice. If you try, you should get a message saying the device is not charging. It may still show up in iTunes and iPhoto, it just won't be charging. No harm, no foul.

If a hub can charge an iDevice, it will usually advertise that feature. As an example, see Anker brand hubs. These have a port that is specifically advertised as able to charge an iPhone or iPad. This particular hub is USB 3.0, and I can't say the capability will exist if you run it as USB 2.0.

IOGear has the manual online and nothing therein mentions charging, so, yeah, 'tis likely that charging can't be done. And I'm not that curious to muck about.

Perhaps if there were a saying about "curiousity"...

Still, many thanks, y'all. The sharing of your wisdom/insight is greatly appreciated.

It is generally safe to charge your iPhone and iPad from any standards compliant USB hub, wall charger, or 12V auto charger. However there are things that should be considered.

1. iPhones will charge with the USB standard 5 Watt power, third generation iPads and iPad Minis require 10 W, other iPads require 12 Watts.
2. USB 1.1 and some USB 2 ports do not provide enough power to charge the battery in an iPad (that is the power available at the individual port, not the total power available to all ports on a hub).
3. USB 3 standards compliant ports will charge any iPad or iPhone.
4. The Apple chargers provided with your iPhone, iPad, and Apple Watch are incredibly complex devices with very sophisticated circuitry designed to.
   1. provide the correct input voltage for your device pretty much regardless of what the input to the charger is. Ie. you can plug into the US Standard 120V 60~ all the way to the European 240V 50~ and the output stays the same.
   2. Filter out electrical spikes and or noise (lots of expensive third party power filters should be this good)
   3. provide more protection for your expensive iOS device than almost any third party chargers.
5. Non-Apple lightning connector cables can effect the rate of charging and perhaps charging an iPad altogether if the power at the port is marginal.
6. iPhones will charge more rapidly from a USB 2 High Power or USB 3 port. On the other hand, there have been reports (AFIK unacknowledged by Apple) that charging an iPhone from a high powered port will shorten battery life. I do know the iPhone gets warmer when using a high power USB 2 or 3 power source for charging.

FWIW I used to charge my iPhone from a USB 1.1 or USB 2 hub all the time, but since the iPhone, and iPad, can now be backed up to iCloud and even the iOS can be updated over a WiFi connection, I seldom connect either of them to my computer any more. Over the years I have accumulated a collection of Apple iPhone and iPad chargers and rely on them for safe charging. That may be anal but iPhones, iPads, and Apple watches are expensive and I prefer not to take a risk.

While on the subject of chargers, for a long time I used a 12V USB charger in my car but I noticed my iOS devices were getting really warm. So warm in fact that my iPad once shut down due to an overheat condition, no doubt the 105° outside air temperature contributed to that. My new car has a 110V 60~ outlet in the back seat and use an Apple charger plugged into that now. Works great and neither device appears to overheat. I am not sure what the built in USB charger puts out.

To add a detail to your excellent summary, even when a USB port power supply is not sufficient to meet an iDevice’s requirements, it may still charge those devices, albeit at a rather slow rate and despite indications to the contrary (‘Not charging’). Consequently, this option is handy in a pinch, but not optimal and decidedly inferior to the preferred charging method with an appropriate charger. Another charging caveat to be considered is the possible overheating you mentioned with certain charging options.

I've got a lot to share on this topic, being both a computer AND an electronics geek.

First a little foundation for those that don't get much into electronics. Voltage is provided on supply, and current is drawn on demand. What this means is the charger supplies the 5 volts, and the peripheral takes what it's given. The peripheral however decides how much load to put on the supply, and thus dictates the current draw. If the peripheral draws more than the supply can deliver, it will either overheat (and possibly fail) or shut off. It cannot reduce the current drawn. (it could drop the voltage to reduce the current, but almost any usb peripheral would choke and stop charging if the supply dropped much below 5v, so that option is NOT officially advocated - if it's drawing too much, pull the plug) CHEAP chargers may not have this failsafe or not properly implement it, and will instead overheat, possibly causing burns, fire, etc. This is what caused all the hubbub recently with knockoff usb chargers from China.

Larger peripherals entering a market with existing lower-current-capacity chargers already present causes a problem then because they have no way of knowing how much current they should attempt to draw before risking overheating the charger. Since many peripherals are "dumb" (not computerized) they can't communicate with the supply using the data pins, which seemed like the obvious solution. So instead they just added a few passive components on the host usb end that don't interfere with data, that tell the peripheral how much power is available. They're in rough values, like 150mA, 500mA, etc. Hooking up a modern device like an iPhone to an older charger that doesn't have this informational feature will get you a "we can't charge from this supply" message on your phone. Devices can also vary the amount of power they draw throughout the charge, to improve battery life and keep things cooler. Slowly starting, then going full draw for "bulk charge", and finally throttling down when they're nearing completion.

Older hubs, particularly USB1.1, will usually get you the "can't charge here" message. Newer ones are usually rated to lower power levels, 500mA max, 250mA typical, and will charge, but slower. They tell the iPhone to go easy on them, and the iPhone slowly sips power and charges up. iPads take quite a bit longer, as they'd LIKE to have 2 full amps. I think the lowest they'll take is 500mA. iPhones want 1A but will also settle for less. Most current USB2 hubs and devices will only put out 1A. (watts=volts x amps, so an iPad that wants 2A will draw 10W of power)

As for heat in the charger... that's an issue of regulation. You've got 110 in the wall, but it's AC, and AC is easy to convert voltage on with minimal loss. Those black wall warts do a pretty good job of getting it down in the ballpark. The hub or computer then does final regulation and filtering, where there's some heat produced/lost. The more current a device draws, the more heat will be produced in the regulation.

Things get nastier when you are trying to go dc-to-dc, like in a car. Car chargers have to use buck-regulators because dropping 12v down to 5v at any reasonable power level is going to produce a ton of heat. The buck regs even have heat problems to deal with, and some automotive chargers can get extremely hot when charging a device that wants the full 5W (1A at 5V) that the charger's option says it can supply. 2A car chargers are rare, so expect your iPad to charge slowly, and really get the adapter cookin'. I tried to build my own, and the buck reg I was using kept overheating, despite being rated 1A without additional cooling. I finally broke down and bought a dedicated USB charge bar that has two 2A and five 1A ports on it. (it's not a hub, there is no computer uplink) It works very nicely and its large metal body keeps it properly cooled.

SO... done wrong, yes there is a hazard. The risk increases when the device can charge faster (1A or more) and the risk is much greater when using a cheap or shoddy adapter. (before replacing my truck power pack, I NEVER left it alone charging something) I'd suggest the same for anyone else. If you simply have to use a marginal adapter to charge a large item, or if you notice the charger or the peripheral getting uncomfortably warm, do your charging somewhere a little more hardened against overheat and fire. Don't tuck your iPhone into an open dresser drawer while charging overnight. Don't leave the iPad on the couch or laying on the carpet charging. It's always smart to periodically check your smoke detectors. Charge large devices near a smoke detector. (at least in the same room) I charge my iPhone on my kitchen countertop, physically isolated on the counter, with nothing combustable (cupboards/curtains) above it and the full (short...) cord's distance from the wall, "just in case".

Electrical 101 - well done. Thanks.