External HDD questions

FockMasterDan · 07-08-2008, 10:53 PM

My carpc is a laptop based setup (already had the computer laying around and it's perfect for the job) and I want a second disc. I want to use a 3.5 drive because I need a ton of storage capacity and a 2.5 either won't cut it or will be ridiculous expensive.

I have not purchased anything yet, so my hands are not tied down to any particular options, but here are my questions.

With powering the drive, I know I will need an external power source for the drive but I don't want to have a ****ty inverter anywhere in the system. What would I have to do to power an external 3.5 in a car DC-DC?

Second what experiences does anyone have with particular cases (I'm shopping for firewire only FYI) or brands for external enclosures. I know many of them leave the disc loose in the case, but I figure that I may have to just do some minor modifications to keep the disc in place. That's no big deal.

My thinking is I can pick up a power supply that is the correct volts and amps and run the HDD, but I wanted to check before I fry a disc.

FockMasterDan · 07-09-2008, 06:34 PM

OK I knew I was going to need something regularted, but after reading up more I see that I can get something like the opus POL power supply and rig it up for the HDD, but I can't find how much power I'll actually need to run a 500gb 7200rpm HDD in a firewire case. I wouldn't imagine it would be that high, but I like to get facts before I jump.

Hopefully this thread won't be another of me just talking to myself.

skuller · 07-09-2008, 06:43 PM

I googled for a seagate 500gb 7200 rpm power requirement, came up between 10-15watt.
Add that with some led and controller on the external case, I am pretty sure you won't exceed 25watt.

FockMasterDan · 07-10-2008, 10:46 AM

I found the numbers for an external that I may just end up going for that is 17 Watts.

Now I need to figure out if the HDD is the only thing I need to power like this to size up what I need.

nasa · 07-10-2008, 11:54 AM

FockMasterDan,

did you mention using firewire? If so, you may not need anything extra:

http://episteme.arstechnica.com/eve/...m/271003431931

"You may want to consider a Firewire drive. They are fast, problem free, and Firewire can feed up to 45 W rather than the paltry 2.5 W of USB. A 3.5" HDD usually takes some 10-15 W at most when spinning up."

Also check here:
http://developer.apple.com/documenta...section_3.html

Wikipedia states,
"It is designed to support Plug-and-play and hot swapping. Its six-wire cable is more flexible than most Parallel SCSI cables and can supply up to 45 watts of power per port at up to 30 volts, allowing moderate-consumption devices to operate without a separate power supply."

Look at this drive for a possible solution:
http://shopper.cnet.com/external-har...017680.html#p5

Amazon says (about above drive) "...Conveniently bus-powered and plug & play..."

I'm not suggesting you buy the above drive, just that it's an example of one doing what you want.

FockMasterDan · 07-10-2008, 12:33 PM

Thanks a lot, I'll look into that. It may simplify things a lot. Now I just need to figure out if the screen I go for eventually will need regulated power, because if it doesn't then I won't need any regulated power source for my devices.

Hurray for firewire.

FockMasterDan · 07-10-2008, 01:32 PM

Now that I see the disc you mentioned is Lacie, I will stay away from it. I'll look for other brands with similar products. Lacie is terrible, they have great products spec wise, but the reliability and customer service is severely lacking. If you have an issue (which you often will) they tell you too bad it's not their problem.

Chairboy · 07-10-2008, 02:35 PM

I've run an external 3.5" drive for years, no troubles. I spliced a cable into a 12v hard drive line from my Opus (which was already powering the computer) and ran it forward to the monitor, and spliced another line to the external hard drive. Everything comes on at the same time and life is well.

Three or four years ago I aborted a switch to a different case when I found that the electronics in the case took too long to initialize, causing the drive to not appear properly when coming out of hibernation, but I think that's rare. Probably doesn't happen nowadays.

FockMasterDan · 07-10-2008, 05:02 PM

Which opus do you have? See I'm running a laptop with it's own power adapter so there is no power supply I can jump on for regulated 12.

I'm having trouble finding a bus powered firewire setup because almost everything with firewire has USB as well, and we already know USB can't handle a 3.5. Grr it has to exist. That would simplify life so much.

I may have to just get something to give me regulated 12 since now that I think about it I'm pretty sure my HUB requires additional power. That may open up my options on the HDD again.

FockMasterDan · 07-10-2008, 05:07 PM

I found what I'm looking for, a bus powered firewire case for SATA 3.5 HDDs, but I just remembered that my firewire port is only a 4 pin, so no way to do bus powered there. Now I'm back to figuring out what type of device to pick up to give me my regulated DC power.

At least that means I can go ahead and just pick a HDD because no matter which one I go with I will need to have a power solution for it.

FockMasterDan · 07-11-2008, 04:29 PM

One last thing to figure out before I go PS hunting, does an external 3.5 HDD need both 12 and 5 V, or just one of the two? Those aren't the kind of specs that are easy to dig up, but from what I gather it does indeed need both.

Chairboy · 07-12-2008, 07:50 AM

I've never seen one that takes both, it's usually just 12v as far as I've experienced.

neilhart · 07-12-2008, 10:09 AM

I was wondering how you are going to connect your laptop power adapter in the car? Is it an automotive adapter with 12 to 15 VDC input?

What is your plan to turn on and off the car computer?

Neil

FockMasterDan · 07-12-2008, 02:15 PM

Quote: Originally Posted by neilhart

I was wondering how you are going to connect your laptop power adapter in the car? Is it an automotive adapter with 12 to 15 VDC input?

What is your plan to turn on and off the car computer?

Neil

I have a DC power adapter designed for the car and will have that wired from a relay triggered by the acc power signal. I then have webmasters unit to turn on the computer.

Then just set it to hiberate after X number of minutes on battery power.

FockMasterDan · 07-17-2008, 03:51 PM

Well I ordered a Maxtor 500gb one touch 4. Staples had some deals and I had a coupon so it was a decent price. Now I can start backing up my data to prepare the carputer for a total reload before I really start setting it up (as soon as it gets here). I do have to reformat the drive right when it shows up though because I want a 100gb partition that is a backup of the internal HDD.