UPS Power Query

**UKGooey** · 12-02-2006, 06:14 PM

I am currently re-organising my current carpc layout and have stumbled across a solution/problem. Can someone give me a nudge in the right direction. I haven't come across any info on any site that may help me, despite hours and hours of searching.

Solution
I have purchased a UPS which I intend to attach to the invertor in my car. The invertor is attached directly to the car battery and is to be switched on with a relay attached to my ATT wire. After testing on my home PC I appear to have solved a problem or two.

I have used it as a shutdown controller, which when set to 10 mins will cover petrol stops etc. and fire up when restarting the car and means that when i turn my ignition off, I can automatically turn off the invertor meaning no more dead battery mornings. This should also sort any crank issues.

Problem
I prefer to manually start my PC (hardly worth turning it on for journeys of less than a minute). When turning the ignition, my invertor turns on. However, the UPS takes a full 45 seconds to turn on. This is before i can even start the PC. Meaning that even on a good day it will take at least 1m10secs to fire up the bad boy!

Anyone know of a UPS that will work in a similar way but with an immediate restart?

Or any other solution? Honestly not bothered too much about wasting money so feel free to be inventive (as long as it solves my problem

).

**psyrex** · 12-02-2006, 07:51 PM

I don't know of any solution, but I would recommend against the UPS. Your inverter->UPS->PSU method for powering your computer means you convert power from DC to AC to DC to AC to DC. You will lose at least half the power you pull from the battery, wasting it by converting electricity into heat.

Why not purchase a DC-DC convertor? Since you don't seem to be too worried about cost nor surviving crank, it will work fine for you. Since it is hooked directly to the car battery, you don't need a UPS to keep to running for 10 minutes after the car is turned off; it will do that anyways.

**Jahntassa** · 12-03-2006, 03:32 AM

What kind of UPS are you using now? I have an old PK Electronics Blackout Buster in my setup that powers on instantly. In fact, pretty much any UPS i've used will supply power in less than 5 seconds. Why does it take so long for yours to start up?

Unless of course, you're draining it completely each time. Then it may need to wait for the battery to warm up? Don't know, only a theory.

psyrex: As far as your comment, I don't think you really lose that much power with a UPS. Generally its only trickle charging the internal battery anyway. I don't think your standard under-desk system will be constantly doing AC-DC-AC. But I could be wrong.. I just know on my UPSs you can distinctively hear when it switches to it's little AC generation mode.

**UKGooey** · 12-04-2006, 02:03 PM

psyrex: I know what you mean. I guess it's a pretty innefficient system, however, besides the UPS it's the way i had it set up for the last year or so. Did it before doing enough research you see

I'm not sure if DC-DC convertor would be enough to power the system (AMD 3000+, 1Gig RAM, 300Gb HD). Guess I've just been patching up as I go along. But I AM worried about crank mate. Gets on my nerves you see. I have to fill up a lot cos car is stupid.

Jahntassa: UPS is a Mustek PowerMust 600. It was cheap and cheerful cos it was more for testing than anything else. Dunno why it takes so long starting up. Cos it's pants? Might be undercharged but I don't think so. It has been constantly plugged in for the last few days.

**psyrex** · 12-04-2006, 03:59 PM

I dunno if they ship to the UK, but there are pretty high powered DC-DC converters: http://www.powerstream.com/DC-PC-12V.htm

**UKGooey** · 12-06-2006, 12:58 PM

Cheers for that. Minimum input voltage is 9V though. I'm guessing that wouldn't survive crank. I suppose this is where a tank circuit would come in? I'm gonna do a bit of research on DC-DC convertors that will survive lower input voltages. Or failing that sort out my UPS problem. Dunno where I got the impression that DC-DC convertors weren't that high powered......