Enough juice to power a 2.5" Firewire hard drive?

[kaidomac]

I want to get a 2.5" Firewire hard drive enclosure to use as backup for my upcoming MacBook Pro. Does anyone know if the MBP has enough juice on the 6-pin Firewire port to run a 2.5" enclosure without extra power? A lot of USB hard drives require either an A/C adapter or an extra USB plug to provide power to the drive.

 

[snoslicer8]

This is, from what I understand, the best part about FireWire. It will drain your battery quite a bit faster, but FireWire is completely Bus powered for 2.5" drives. Makes travelling with them quite a bit easier.

For what it's worth, I have a 2.5" USB 2.0 enclosure for my backup drive, and it runs on 1 USB port. The enclosure came with the "y" adapter, but I don't need to use it.

 

[kgeier82]

i was under the impression that the fw400 port was unpowered? i could be wrong, thinking about my old i6000 and its 4pin port.

i know for sure the fw800 plug is powered, surely enough for an external 2.5

 

[Aptmunich]

Firewire 400 with 4 ports is unpowered, fw 400 with 6 ports is powered.

All Firewire 400 2,5" drives have worked on my iBook and Macbook without an additional power supply so far, so I think you'll be fine.

 

[kaidomac]

This is, from what I understand, the best part about FireWire. It will drain your battery quite a bit faster, but FireWire is completely Bus powered for 2.5" drives. Makes travelling with them quite a bit easier.

For what it's worth, I have a 2.5" USB 2.0 enclosure for my backup drive, and it runs on 1 USB port. The enclosure came with the "y" adapter, but I don't need to use it.

What kind of drive are you running? I have several drives that I will be using, including a 4200, 5400, and 7200rpm. From what I've read, the larger/faster the drive the more power it uses and thus the less likely it will be able to run off bus power.

 

[mynameis]

I have no trouble running a 2.5in hard drive using only the power from at USB port. Why not get USB?

 

[dtravis7]

Only Bus powered external I have is a Western Digital 80GB USB 2.0. It works great with my iBook with no external power. All my Firewire externals are large and powered.

 

[Osiris22x]

I've never had a Firewire 400 drive not successfully power up on any Mac. You should be fine.

 

[kgeier82]

What kind of drive are you running? I have several drives that I will be using, including a 4200, 5400, and 7200rpm. From what I've read, the larger/faster the drive the more power it uses and thus the less likely it will be able to run off bus power.

no matter what speed it is, it should work.

they use more power yes, but not even 1.5x as much it seems from what ive seen.

 

[kaidomac]

Did some more research. MacBook Pros supply 1.5 amps of power at 12 volts, which translates out to 14 watts if only 1 port is being used or 7 watts per port if both are being used. Details here:

http://docs.info.apple.com/article.html?artnum=304573

I discovered that the 250gb Western Digital "Scorpio" hard drive uses a maximum of 2.5 watts at 500mA (0.5A), which is well within the range of the MacBook Pro's power specs:

http://www.wdc.com/en/products/products.asp?driveid=314

So the last thing to do was to find an enclosure that would support that kind of power rating. CoolDrives sells one that can handle a maximum of 3 watts:

http://www.cooldrives.com/2esusb20fi40.html

I think I've found my backup drive solution

 

[Soulshiner]

I am running a MacBook Pro with a LaCie Porsche 160 gig moblie drive that does not power up from the Firewire 400 port. Neither does my Iomega 500. Is there some setting on the Mac that needs to be tweaked?

 

[wytwolf]

2.5 inch HD are generally bus powered (usb2 or FW). It's the 3.5 inch externals that require the AC adapter to operate.