M3-ATX 125 watt Smart Automotive Power Supply

Although those PicoUPS look fairly economical, an alternative may be a 2nd battery which is only connected (to the primary battery and charger) whilst the vehicle is charging.

See f.ex mp3car's Smart Battery Isolator (Post#7) - and for derived circuits - Using a relay to auto-power on HDD and power inverter (page 2).

For a low voltage cutout to protect the 2nd battery, you could use an MW728 "Battery Guard" (~$20).
Although the MW728 switches 10A, by having it switch a 12V relay instead, series diodes can be inserted to increase its 11.2V cutoff voltage upwards in .6-.7V or .2-.3V increments etc.

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Originally Posted by OldSpark

Although those PicoUPS look fairly economical, an alternative may be a 2nd battery which is only connected (to the primary battery and charger) whilst the vehicle is charging..

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Thanks for the reply OldSpark. I had considered going with a 2nd battery and isolator, since I have a spare battery and an old isolator kicking around from an old car stereo installation. However, I am lacking on space for a full-size secondary battery and considered an installation of that magnitude overkill for this particular application.

Even still, the isolator/secondary battery solution would not solve the M3 'hard off' dilemma. The advantage of going the PicoUPS-120 route is that the M3 is never connected directly to a permanent 12v source, therefore I will never run the risk of the M3 discharging my car battery while the ignition is off. Instead, the PicoUPS charges off of the ignition line and supplies 12v 'battery' voltage to the M3 on the PicoUPS output.

I did do some tinkering over the weekend and with a makeshift serial cable, I was able to connect the M3 to the external RS-232 line of my CarPC - using the downloadable software from the Mini-Box site. It appears that they have limits on their 'custom' settings, with the upper-most threshold on the 'hard off' delay being a time of 17:59:59. I believe this limit to be the result of the system code using a 16-bit integer value on the variable used for number of seconds - i.e. 17:59:59 equals 64,799 seconds, just shy of the 65,535 limit of a 16-bit integer.

I'm awaiting a response from the folks over at Mini-Box, but this limit will suffice for daily use (provided the small lead-acid battery will last this long), and much better than the two-hour default settings. The only time I will need to perform a cold boot is if the car is not used over the weekend.

I purchased one for my D945GCLF2 thinking it would just plug into the main power connector. I have searched the forums for the right power supply and thought the M3/ATX is what I needed. It dosent appear to just plug into the main power connector. I wonder if I have purchased the wrong power supply.

It does fit the D945GCLF2 correctly. You may however encounter power problems when using many USB devices.

It does ? I didnt want to force it but it appeared that the socket is not the same size. I will keep trying to see how exactly it fits. Thanks for the quick response.

so it does fit. it does leave 4 pin sockets open ? I plugged it in on the left side of the plane.

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Originally Posted by Technoid

so it does fit. it does leave 4 pin sockets open ? I plugged it in on the left side of the plane.

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Yes - that's the proper method for using the M3 with the D945GCLF2. The extra four pins on the motherboard are for additional current on the +12v, +5v and +3.3v lines along with an additional ground. The M3 has plenty enough juice in the 20-pin molex to supply the D945GCLF2 with all the current it needs.

It should look like this:

http://www.playtool.com/pages/psuconnectors/20in24.jpg

Keep in mind that in addition to the 20-pin molex, the D945GCLF2 also requires a separate 4-pin 12v/Gnd connector for additional CPU current. The M3 does not come with this 4-pin connector, however you can use an adapter such as this http://www.mini-box.com/4-Pin-P4-Power-Cable to supply the P4 power.

Good information. Thanks NibbleIT and fiscap.

I really needed that last comment there, I have an Asus A5IONT-I motherboard and didn't realise that it was actually a 24pin ATX plug! Good to know my M3 will be able to power it anyway. :)

Anyone know the coding for the status LED? The only mention of it in the manual is when restoring the factory default settings using a jumper:

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The LED light will start to flash rapidly indicating that the factory defaults were loaded.

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So what does it mean when the LED flashes slowly? What does it mean when the LED is on solid?