Page 4 of 5 FirstFirst 12345 LastLast
Results 31 to 40 of 45

Thread: M2-ATX ACC line instead of IGN?

  1. #31
    What can I say? I like serial. Curiosity's Avatar
    Join Date
    Mar 2004
    Location
    Florence Yall, BFKY
    Posts
    2,684
    Quote Originally Posted by RevheadKev View Post
    @ Curiousity & trader007,
    12V relays have a minimum operating voltage where they will drop out.
    You should check the cranking volts to make sure this is not below the dropout voltage of the relay you use.
    The dropout is the reason for the dropout filters discussed. (excluding the resistor on mine since there are diodes). Of course that doesn't mean the PSU won't shut down.

  2. #32
    FLAC
    Join Date
    Dec 2008
    Posts
    1,322
    Quote Originally Posted by CraziFuzzy View Post
    My M2-ATX, as it's aged, has been less capable of surviving engine starts (down to about 30% success rate I'd guess). It has nothing to do with the acc line, as it can be off for 5 secs and it won't shutdown. The problem comes from the voltage dropping on the +12V line when starting the engine. My M2-ATX could easily handle this when it was new, but lately, drops out far too often. My current plan (next time I get into the center console) is to install a diode isolated Sealed Lead Acid (small, like for security systems/emergency lights, etc) and run the PC from that. This should easily maintain the power the M2-ATX needs on the main supply, and will be maintained on through engine starts.

    might actually be the way to go, because apparently it seems the voltage on the batt+ line of the m2 is whats dropping too low and making it reset. because even if the relay is dropping out, the m2 has a 5 sec off delay built in anyway...

  3. #33
    Variable Bitrate
    Join Date
    Nov 2006
    Location
    Rubidoux, CA
    Posts
    275
    Quote Originally Posted by RevheadKev View Post
    @CraziFuzzy,
    As your main battery gets old the internal resistance increases with sulphation. This increased internal resistance results in lower external voltage under heavy loads like cranking.
    I would try a new main battery because while it might still work under normal conditions, it sounds like it won't survive if you have to try starting a stubburn engine a few times.
    Yeah, i realize the voltage drop will change as a battery ages, however, in this case, since the M2 started acting up, I've actually replaced the battery, and it made little change. The M2's low-end cutout voltage seems to have raised over time, and the same starting drop that was fine before, no longer is. No worry really, the M2 is still a great PS, it just can't survive the start without a back-up plan. I had always planned on installing a separate battery for coverage during cranking anyways.. (I'd prefer to keep all the PC components powered up as well, but not put extra load on the batt during cranking.. so this will handle that as well).
    2000 Ford Expedition Eddie Bauer - Bi-Fuel Gasoline/CNG
    Intel D945GCLF2 w/512MB RAM, CL Audigy w/KxProject, M2-ATX, Lilliput EBY701

  4. #34
    What can I say? I like serial. Curiosity's Avatar
    Join Date
    Mar 2004
    Location
    Florence Yall, BFKY
    Posts
    2,684
    That can also happen if you increase current requirements, by adding USB devices or other components, upgrading the PC to something bigger, etc. The current required to boost is higher than the output. For simplicity, say double (plus some) the output amps at half the volts.

    Also, the one bad thing about using just a diode with an SLA battery instead of an isolator is that when the battery starts wearing out or shorts a cell, it will drain your main battery. So keep that in check.

  5. #35
    Variable Bitrate
    Join Date
    Jan 2006
    Posts
    345
    Hmmm. I'm trying to work out why it only happens for me sometimes. I figured there was a voltage drop on the 12v+ line the moment I cranked, because the engine needs the juice to start up. But my PC only resets itself sometimes, not every time, and I have not added any extra USB devices. The battery is the one that came with the car when it was bought brand new in May 2007.

    The only time I've had trouble starting the car was when I had the car off and car PC on, and I used the car PC for about one hour (playing music, watching movie clips, surfing the web). Then when I cranked, the engine turned a little and the PC instantly switched off and didn't turn on. And then the engine would just make a clicking noise. I jump started it and it's been fine ever since.

    So now I probably need to rig up that diode circuit and see how I go.

  6. #36
    Raw Wave
    Join Date
    Nov 2009
    Posts
    2,119
    I agree - weak battery. (Or bad connections/cables etc.)

    Usually in that case though if relays drop out, they don't pull back in - ie, 12V relay may pull in at 8V and drop out @ 5V.

    But there are inductive spikes etc that can cause the relay to pull in.

    You could try a different relay - a new one or one with a lower drop out voltage.
    Or ensure good connections.

    Or Curiosity's RC network, though ironically that's what we were trying to avoid in the first place.


    I try to design for an 8V - 16V operational range automotive stuff.
    Many systems won't work below 8V and many vehicles won't start that low either (no CPU, slow starter, no spark) - some not below even 10V. (Mine starts cold at 5.2V but is carby - not EFI.)

    It's also a reason some use a 2nd battery for PCs etc.

  7. #37
    Variable Bitrate
    Join Date
    Jan 2006
    Posts
    345
    I don't mind having the RC network but I'm not sure if it will fix my problem.

    I'm using 16awg wire on the 12v+ line and this seems adequate because it doesn't heat up at all (perhaps the section that's close to the battery gets warm but that's due to engine heat, not a result of too much current on a thin wire).

    I might have a look at the -ve connection because it might be a bit loose - I tied it tightly around a small hole in the chassis just behind the car PC when I installed it.

  8. #38
    FLAC
    Join Date
    Dec 2008
    Posts
    1,322
    Quote Originally Posted by OldSpark View Post
    I agree - weak battery. (Or bad connections/cables etc.)

    Usually in that case though if relays drop out, they don't pull back in - ie, 12V relay may pull in at 8V and drop out @ 5V.

    But there are inductive spikes etc that can cause the relay to pull in.

    You could try a different relay - a new one or one with a lower drop out voltage.
    Or ensure good connections.
    it shouldnt matter if the relay clicks out for a second... the m2 waits 5 seconds at least before it does anything anyway... the m2 itself is malfunctioning, and from what i can tell either a backup battery on the batt+ terminal is needed, or a large capacitor (not sure how many farads it would take to keep the pc running for a couple seconds, but i can find out). myself im actually leaning towards capacitors for nothing other then reliability.

  9. #39
    Newbie Exstatica's Avatar
    Join Date
    Apr 2010
    Posts
    12
    Quote Originally Posted by trader007 View Post
    it shouldnt matter if the relay clicks out for a second... the m2 waits 5 seconds at least before it does anything anyway... the m2 itself is malfunctioning, and from what i can tell either a backup battery on the batt+ terminal is needed, or a large capacitor (not sure how many farads it would take to keep the pc running for a couple seconds, but i can find out). myself im actually leaning towards capacitors for nothing other then reliability.
    If you figure out how many farads are needed let me know, I'd be interested in that also.

    However I do have a yellow top battery, I'm hoping that it can support the engine crank, and not affect the PC

  10. #40
    North of the land of Hey Huns
    Auto Apps:loading...

    Join Date
    Jun 2004
    Location
    Westminster, MD
    Posts
    2,144
    Assuming your carpc uses say... 4amps? That's 48 farads per second you want to run(iirc). That's ignoring the fact that towards the end if it, your voltage is going to drop to an unusable amount.
    "stop with the REINSTALLS, what do you think we got some lame-o installer!!!" - mitchjs
    RevFE
    My Shop

Page 4 of 5 FirstFirst 12345 LastLast

Similar Threads

  1. How to keep your invertor alive while cranking.
    By MiniRX7 in forum Power Supplies
    Replies: 37
    Last Post: 07-27-2005, 09:03 AM
  2. Question on Line Out of M10000 and Audigy NX
    By Mears in forum General Hardware Discussion
    Replies: 24
    Last Post: 06-10-2004, 04:00 AM
  3. Easy way to mute/unmute line in ?
    By liquid_smoke in forum General Hardware Discussion
    Replies: 17
    Last Post: 12-31-2003, 01:02 AM
  4. ATX PSU Hack with inverter (Old subject I know)
    By dekodan in forum Power Supplies
    Replies: 5
    Last Post: 08-01-2003, 08:15 AM
  5. New Idea for an awesome atx shutdown
    By moahdib in forum Power Supplies
    Replies: 78
    Last Post: 07-03-2002, 11:42 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •