M1-ATX Wiring Question

Imobejoas · 01-31-2005, 11:21 PM

I just got my M1-ATX today, It has a white wire I'm assumming is connected to the switched (ignition) 12V lead.

I was wondering....

1. If the white wire was just a relay wire, and if so, does the guage of wire have to be that thick or could it just be any wire (not too thin of course) wired up to the switched 12.

2. Does the M1-ATX run off of the ignition switched 12v or the always on 12V? I'm guesing the always on 12v, but I just wanted to double check.

3. Where should I hook up the 12V ignition switch wire? I was thinking up to my head unit, but the head unit wire is already pulling it's own load and the vga screen.... one more gonna be okay? If not, then where else?

Thanks in advance!

rando · 02-01-2005, 12:30 AM

The 12V always on connection should be powered from a new circuit run directly from your battery. This is the main power wire and should be size appropriate to handle the maximum input current of the supply as well as to avoid voltage drops which will lower your hard cutoff margin -- 8 to 12G is appropriate depending on the length of your runs. The IGN line can be sourced from whatever is appropriate for your setup. The supply only uses this line to for logic level switching. 18G should be fine.

* I don't anything about the wire colors you're talking about. My M1-ATX did not come with any power wires -- just 3 spade terminals.

hcker2000 · 02-01-2005, 12:54 AM

I just installed my m1-atx. Before hand I tested it with about 6 feet of 22awg wire and powers up just fine and dose every thing it should with no problem (survives crank). Wire didn't even change temps. Just leting you know that you can use a smaller wire if you have some laying around and don't have any extra cash. PC is a via M10k with slim 8x dvd rom, full size hard drive, dlink 802.11 b/g pci card, usb blue tooth, usb keyboard, usb mouse. The m1-atx was also powering a noritake 7000 VFD.

rando · 02-01-2005, 09:13 AM

22AWG is way too small for extended use at full power. Also, at high power levels, you will see a substantial voltage drop over 22AWG. This will cause the low voltage shutdown feature to kick in earlier.

bd3521 · 02-01-2005, 06:36 PM

So what AWG should be used?

Imobejoas · 02-01-2005, 08:08 PM

The way I see it, since I'm using a Morex 3688 box. From the socket to the power supply pcb, they are using 18AWG wire. The THINNEST wire then, should be 18gauge wire. I think 14 stranded should be more than adequate. The wires in the house, supplying 120VAC are using 14 IIRC. Heck, from the power brick of my case to the socket isn't even 18GA. So 18 should be OK

rando · 02-01-2005, 09:26 PM

Quote: Originally Posted by bd3521

So what AWG should be used?

See post #2.

rando · 02-01-2005, 09:33 PM

Quote: Originally Posted by Imobejoas

The way I see it, since I'm using a Morex 3688 box. From the socket to the power supply pcb, they are using 18AWG wire. The THINNEST wire then, should be 18gauge wire. I think 14 stranded should be more than adequate. The wires in the house, supplying 120VAC are using 14 IIRC. Heck, from the power brick of my case to the socket isn't even 18GA. So 18 should be OK

This has been discussed here and elsewhere countless times before. If you use 18AWG for your power mains, you will almost certainly run into problems. Here's a reference site I pulled up on Google. There are many others.

http://www.powerstream.com/Wire_Size.htm

drait · 02-02-2005, 10:23 AM

@rando: I wired my M1 with 16 gauge from the power distribution block near my amps (which has 8 gauge wiring to the battery). Do you think this thin of wire is what is causing my M10K to occasionally beep upon resume from hibernation? Here's a quick scenario: I go to a gas station, turn off the car. M1 is set to hibernate after 5 seconds, and power off 5V after 45 seconds. After filling car (say 3-4 minutes) I start it back up. Instead of the M1 turning on the M10K, it makes the motherboard emit repetitious beeping from the peizo every 1.5 seconds. The only way for me to "fix" this is to pull the +12V (or ground) lead from the M1 and then reconnect it. I've often wondered if this was a power-related issue, or if my M10K is bad. Mind you, it doesn't always do this, just when it seems like I've stopped for a very short time. If I leave the vehicle for any extended period, it starts up just fine.

Imobejoas · 02-02-2005, 11:59 AM

Short 1 to 2 ft distances 18 is okay, voltage drop is minimal. If you are bent on using 18 guage, one solution is to have a few 18 guages in parallel, which will divide your RDC by the number of 18 ga you use.

I think that's the route I'm going to take. I have plenty of 18ga. And my existing 18guage has a socket connector which convientiely plugs in.

rando · 02-02-2005, 01:23 PM

I agree, if you keep it short, you'll probably be OK from a voltage drop standpoint -- though 10A is still pushing it a bit with 18G. Typical 18G connectors will have even more of a problem handling the current. Multiple strands is an option but it takes several just to get upto the next wire size and ultimately it just makes things messier.

My advice, spend the extra few bucks and get the right wire.

rando · 02-02-2005, 01:25 PM

Quote: Originally Posted by drait

@rando: I wired my M1 with 16 gauge from the power distribution block near my amps (which has 8 gauge wiring to the battery). Do you think this thin of wire is what is causing my M10K to occasionally beep upon resume from hibernation? Here's a quick scenario: I go to a gas station, turn off the car. M1 is set to hibernate after 5 seconds, and power off 5V after 45 seconds. After filling car (say 3-4 minutes) I start it back up. Instead of the M1 turning on the M10K, it makes the motherboard emit repetitious beeping from the peizo every 1.5 seconds. The only way for me to "fix" this is to pull the +12V (or ground) lead from the M1 and then reconnect it. I've often wondered if this was a power-related issue, or if my M10K is bad. Mind you, it doesn't always do this, just when it seems like I've stopped for a very short time. If I leave the vehicle for any extended period, it starts up just fine.

Possibly but you may have other problems -- just look up what the beeps meen in your motherboard manual.

Imobejoas · 02-02-2005, 02:16 PM

Since I'm fairly new to this board, and I don't want to read all those posts from day 1, I did some testing of my box.

I have DC source at my company. And I hooked up my M10K with M1-ATX powersupply. Barebones setup:

40GB 4300RPM HDD
IBM 8x DVD Slim Line
512MB PC2100 Kingston RAM
ps/2 keyboard
no mouse, no monitor or usb devices.

I set up a 12V source, with Fluke Multimeters (calibrated) to monitor Voltage and Current. Grabbed some random 3ft 18ga wire and plugged it into my morex 3688.

The system pulled a MAX of 3.2 Amps
Voltage drop over 3 ft of 18GA wire: NEGLIBLE (.01v -.02v)

I estimate that with USB devices plugged in I would see a max of 5amps, 6 to be on the safe side.

rando · 02-02-2005, 02:53 PM

Depending on your exact 18G, you might have seen around 0.1V drop at the load under those conditions. At 6A, this will creep upto the .3V range. Extend your wiring to 10 ft (say wiring in the trunk) and at full load (10A) you could get 1.5V drop ... enough to cause your supply to shutdown.

Imobejoas · 02-02-2005, 03:48 PM

That's the thing... It will creep to 6A peak maybe if I were to load it with a ton of USB devices (each drawing 0.3A max). But with what I had and everything hooked up it was averaging 2.5A, 3.1A tops.

For my car setup, I already have 4GA running to a distro block, which splits off to the amp (8ga) there. My wiring should be no longer than 8ft from the distro block to under my front seat.

For the test bed purposes above, the wire was 3ft+ The drop was insignificant. Not even .1V, it was 0.01V if ANY (my fluke doesn't have .0001 precision)