powering external hard drive

All right, I have an 04 silverado. I purchased a Pioneer 6900 head unit, usb controlling, and a 250g external usb hard drive. I want to leave my hard drive in my truck, probably will put it in my glove box, but I do not want it to drain my battery. It would be a pain to have to turn it off every time I got out of my truck, and if I forgot my battery would be drained. I am thinking a relay system is the solution, but I am unsure how to hook one up with the power inverter necessary to power my hard drive. Any help would be greatly appreciated.

Assuming it does not have its own transformer, you'll need to find a way to provide 5V power to the drive and you'll need to wire it in through a USB cable. You will also need to determine what the amperage requirement is for the drive so you can size the transformer correctly. THIS is likely to be the hard part... The relay is the least of your worries here and is pretty simple: run your 5V power to 87, 30 to your HD, your ignition coil or switch to trigger the relay to 86, and 85 to ground. If I missed what was confusing you, then sorry for the long answer :)

The makers of the hard drive were thoughtful enough to provide an adapter. It plugs into the outlet in a house. That is where I was thinking power inverter. I would just hook the inverter to my battery and plug the adapter into the inverter. The problem is that it would be on 24/7. My trouble is: where I should put a relay, and if it should be done.

All right, I have an 04 silverado. I purchased a Pioneer 6900 head unit, usb controlling, and a 250g external usb hard drive to put music on. I want to leave my hard drive in my truck, probably will put it in my glove box. The makers of the hard drive were thoughtful enough to provide an power adapter. It plugs into the outlet in a house. That is where I was thinking power inverter. I would just hook the inverter to my battery and plug the adapter into the inverter. The problem is that it would be on 24/7. To solve that, my thoughts turned to a relay. I have never set one up before, but I have done the basic research on it. Any advice/help?

First of all, the deck (I can almost GUARANTEE you) will not look at NTFS partitions, which is how that drive will be formatted. It will have to be formatted as FAT32, and good luck with that. 2K and XP will MOUNT and CREATE FAT32 partitions that big, but neither of them can format it - it will fail the format, and you'll end up pulling your hair out trying to figure it out... Not only that, but you CAN puke your drive completely. Now your drive is useless. Just be careful doing that. There isn't anything really stated as to the format requirements in the owner's manual, but I've never seen anything EVER be able to read NTFS patitions, except MS operating systems. Secondly, will the deck even see a drive that big, even if formatted correctly?? Being as it is designed for iPod control and reading, I'd be willing to be that the biggest partition it CAN see is 32GB. I was going to do the very same thing with the new Alpine iDA-X001, and it won't even see a partition as big as 160GB. I have an external USB 160G hard drive, and it couldn't see it. I'm going to TRY to make it work still, but I don't have TOO much hope for it... Thirdly, the new Seagate "Desktop FreeAgent" comes with a 12V power requirement, as hard drives use both 12V AND 5V internally - 12V for the motor, and 5V for the logic. You can't provide it with just one voltage, UNLESS the drive enclosure containg regulators for both voltage rails. The FreeAgent also powers down by itself when there is no device detected on the USB port. It was powering up and down perfectly, when I would turn the Alpine HU on and off, so as soon as you turn the ignition off, even if you were to provide a battery connection (i.e. always on) the HD would power off automatically.It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

Hmm, well I did my research. My unit sees and controls usb devices up to 250gb, and uses fat32. It wasn't designed specifically for iPod, but for any usb device - iPod, zune, flash drive, etc. The drive came preformatted as fat32 (yay!) and I already put music files on it - they work fine. As for voltage inputs, I was going to use the adapter that came with it. No need to worry about its requirements. Sadly, my drive doesn't have that convenient feature of powering off by itself, which is why I am considering a relay. I'm thinkin this: battery --- relay --- inverter --- adapter to power the hard drive               |               |               |            ignition Will the relay be able to handle the power?

Other than continuing to try to steer you away from using an inverter then yes, what you are suggesting will work. I believe I even told you how to hook it up in my previous post :) 30 to inverter, 12V to 87, ignition to 86, 85 to ground. Just make sure you size it correctly for the amperage that inverter you choose will draw. Now, why should you not use an inverter: 1. They are hard on the vehicles electrical system since 1 A @ 120 V = 10A @ 12V. 2. In this case, you are just going to convert the power right back to 12V again!!! So basically, you'll start w/ 12V, convert it to 120V with an inverter, and then back to 12V again with a transformer! Are you sure the USB HD cannot be powered via the USB cable itself?

Sadly, it needs a separate cable to power it, not through the usb :/ . Here is a simple picture of what the hard drive needs plugged into it.                 . . . .        . 5V   12V.       .           .        . GRD GRD.         . . . . Though the 12V is straightforward, would I just get an adapter of some kind to get the 5V power?

Right - you need a 12V to 5V transformer that provides the appropriate amperage (look on the power adapter they nicely provided you - it should have an amperage rating). Have you resolved whether or not the read head parks itself automatically during a sudden loss of power (which will be every time you shut the car down)?

1.2 amps at 120V soooo bout 25 amps at 5V? It has been a while since my physics class. I think the HD would keep running if the car turned off.