Define "a Life"...

... still searching for a clear definition of that thing people keep telling me I need to get...

Location: Springfield, PA

Monday, July 02, 2007

Calling All Compu-geeks

I have an unimportant but curious question for those computer geniuses who visit here. (You know who you are.)

We all know USB 2 is way faster than USB 1. One of the main reasons my iPod is synched to iTunes on my iBook rather than on my iMac is that my iMac is an old snowy gumdrop and has USB 1 and my iPod is of one of the more recent generations, which synch via USB rather than FireWire on the assumption that all currrent machines have USB 2. The reason early generations of iPods connected thru Firewire? Because USB 1 would've made syching terribly slow. The speed on USB 2 is comparable to (I think perhaps better than?) Firewire 400, and I guess the USB connection is more universal, so iPods are now USB. And, yes, I'm sure there's something out there that I could buy which would let me connect the iPod to the iMac via Firewire, but it's just not enough of an issue to warrant spending money on. It's not the data-transfer rate that I'm curious about.

My iQuestion has to do with the fact that the iPod charges through its USB connection when it's hooked to a computer. So here's the drill: My iPod synchs with my iBook (USB 2), but since my iBook isn't always sitting on my desk I'll sometimes plug the iPod into the iMac just to charge it. And. This. Seems. To. Take. Forever. I've never timed things, but it seems the iPod charges pretty quickly when it's hooked to the iBook (the iBook being plugged in, of course -- why drain its battery to charge the iPod's?). The only other means I have of charging the iPod is in my truck through the Griffin RoadTrip (the gizmo that plugs into the truck's 12v powerpoint and broadcasts into the very crowded FM airwaves around Philly (which is another gripe altogether), charging the iPod at the same time). Now, when I'm not running the iPod but just have it plugged into the RoadTrip to charge, the little guy zooms to a full battery in what seems like no time. I've run it flat at work, put it in the RoadTrip while I went to lunch, and returned around an hour later to an iPod with full charge. I can attest that through the USB connection on my iMac the thing takes well over an hour to charge to full.

So, if you've read this far, here's the meat of the question: Does the difference in charge speeds have anything to do with the differences between USB 1 and 2? Or is it just that the USB port into which the iPod gets plugged on the iMac is one device down a USB chain? (It's plugged into the open USB port on the keyboard, which acts as an unpowered hub for the mouse and, frequently, a convenient port for flash drives. ) On the iBook, it gets plugged directly into one of the two primary USB ports.

This may be a little too hardware based for those of you adept at parsing code and pushing pixels, but I thought I'd ask. Now that the iPod is becoming more and more ubiquitous in my daily life, I'm finding that its recovery periods matter to me and I'm considering getting it a stand-alone charger. Battery behavior may be enough of an issue to warrant spending the money.


Blogger christianready said...

As a developer/pixel-pusher myself, I may be wrong on this but from everything I've read, USB 1's slower throughput also applies to current as well so yes, it would charge faster.

It's a shame they never introduced firewire on the iPods, but I'm sure that's because Apple wanted to reach the widest audience possible and didn't see the need to spend all that extra money for a feature only a small percentage would ever use. USB 2.0 (8-9x faster than 1) seemed like a good compromise.

4:50 PM  
Blogger Eric Aitala said...

You should be able to get a little power brick which accepts the USB cable and plugs into a standard outlet. It might be worth it...

I mostly use my iPod in the car, so its always plugged into my RoadTrip.... fortunately there are not too many radio stations up here...

Must finish listening to This Week in Tech.... hehe


5:03 PM  
Blogger Andy said...

I could be all wet here, but I believe that some USB ports are powered and others are not. My Palm charges very quickly thru a Powered USB (as if I had the power cord in). Unpowered is what they call a trickle charge.

7:56 PM  
Blogger Andy said...

I also own and iGo. (Just google it) which is a nice power option

8:02 PM  
Blogger Eric Aitala said...

Oh one more thing. Are you plugging the iPod into the USB port on the iMac keyboard or the port in the iMac itself. I think that the keyboard port may not be a powered port while the iMac one is...


8:18 PM  
Blogger Greg! said...

I knew y'all were out there.

Chris -- The first generation(s) of iPods used Firewire 400 to connect. Now I think everything's USB 2.0. I suspect Firewire 800 is rare enough that the demand doesn't justify the additional noodling with the Pod to make it both USB and Firewire 800.

Eric & Andy -- Yeah, I'm plugging the iPod into the keyboard port, which is probably not powered. I guess I could interrupt the USB chain off the other, powered, iMac port when I want a quick charge. Or invest in a powered hub. Or I could just get a little AC charger thing.

Thanks, guys.

12:07 AM  
Blogger Rob said...

Greg -

I think what was said about the trickle charge is correct.

If you want to get an AC adapter for the iPod I found a great deal on both an AC adapter and car charger here:

Can't hurt to have an extra car charger and that set sells for $40 in a big store like Best Buy. They're in Brooklyn NY so shipping was like $3 and it got to me in Nj in two days. Well worth it.


11:00 AM  
Blogger Andrew said...

The power standard for USB didn't change between 1.0 and 2.0. It's the keyboard. Here's why:

A USB port on a powered device (e.g. your iMac or a powered HUB) offers 5V of power with a maximum draw of 500mA. All unpowered devices that share that port divy up the 500mA in 100mA increments.

Therefore, the keyboard uses a minimum of 100mA, leaving a maximum of 400mA for the iPod. The keyboard might use 2-300mA, further reducing the iPod's share.

That's why the iBook's USB charges faster than the iMac's keyboard. However, the Griffin RoadTrip charges even faster. Here's why:

The iPod dock connector has pins for both 5V USB power and 12V FireWire power. Since the RoadTrip has a built-in dock connector and connects to a 12V power source, it no doubt supplies power through the 12V dock connector pin and achieves the fastest charge rate.

In case this isn't already too much information, see more about USB Power and the iPod dock connector.

3:54 PM  
Blogger Greg! said...

Yea Andrew! I knew one of my compu-techie friends would have a truly thorough answer to this. Thank you.

10:05 PM  
Blogger Andrew said...

Glad to oblidge.

5:58 PM  

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