Thread: ITPS + 3.5" Hard Drive == Death?

Originally Posted by soybeanstorm

I think I read in a *VERY* long thread in this forum once (can't seem to locate it anymore) that systems with 3.5" hard drives won't shutdown properly with the ITPS regulation (due to the 12V line dropping to 10.x volts when the engine is off?). Anybody want to verify that this is true (and that I'm not just butchering things together after hours and hours of reading?).

Read it again - ITPS Regulation

haha. good stuff. I re-read all *5* pages of that thread.. A simple, "You're on the money" would've sufficed, but what's the fun in that, right?

Anyhow, I'll summarize it up for any other newcomers.. maybe it'll save someone some time:

Using ITPS w/regulation:
- Drops 12v rail to ~10.x Volts when car is off, as a result:
- Don't use 3.5" drives when using ITPS w/ regulation
a) The 10.x volts on the 12v rail causes the HD to flip out
(when you turn your car off.. so shutdown controller doesn't really
have a chance to do its thing with the flipped-out HD)
- 2.5" Laptop HDs are fine since they only use the 5V rail
- ITPS regulation only allows a maximum of 60 Watts through.
- ITPS w/ regulation + PW-70A? Still only 60 Watts. The weakest link
ruined the party for everyone. boooooooooooo

I hope I got that right. Seasoned car PC guys, feel free to correct anything I may have gotten wrong.

Originally Posted by soybeanstorm

haha. good stuff. I re-read all *5* pages of that thread.. A simple, "You're on the money" would've sufficed, but what's the fun in that, right?.

Well, we had to read it! Not only *5* pages but over *5* weeks!!

Originally Posted by soybeanstorm

Anyhow, I'll summarize it up for any other newcomers.. maybe it'll save someone some time:

'Cause it's a case of life or death that they get their car pc installed??

Originally Posted by Laidback

'Cause it's a case of life or death that they get their car pc installed??

You're right on the money!

If i have a 3.5" hd in an external enclosure, its 12v line hooked up to a relay controlled by the itps sort-of, will that be unhealthy for hte drive at all?

If the 12v line going to the HDD is unregulated then it could be...what do you mean 'controlled by the ITPS sort-of'?

So if you use a laptop hard drive, the shutdown controller on the ITSP will work fine. What about surviving the crank?

Originally Posted by morgant6911

So if you use a laptop hard drive, the shutdown controller on the ITSP will work fine. What about surviving the crank?

It's possible in theory depending on which PSU and system board you use but I think it depends on whether the PSU or system board monitors the 12v rail.

I have a Seagate 5400 U Series disk, an ITPS and a PW-60. The hard drive is the least of my problems! Seems to work ok when the ignition is off, haven't tested the voltages with the car off, but they've been screwey all along. My 3.3V rail sits on about 2.4V when the car's running.. 12V is spot on mostly, 5V is between 4 and 5V. The system runs okay most of the time, car on or off, but it tends to reboot randomly sometimes when I do a heavy read on the hard drive (especially when the ignition is off) and reboots often when going into windows or coming out of hibernate. I'm attributing that to the power good line dropping.

The ITPS/PW60 combination has been nothing but trouble for me. When it works, it's ok. The rest of the time it makes me want to take it out and smash it on the road....

Anyway I've ordered an Opus 150W to replace it, and I'm also going to use thicker grade wire on that. Fingers crossed. Power has been the second most expensive part of the project, second only to the Xenarc...