Why did I buy an inverter?!?!?!??

**rybitski** · 05-12-2008, 09:38 PM

Well I figured that I would go the simple and cheap route buy buying an inverter. (despite what I have read)
I purchased a brand new whistler 400W continuous 800W peak inverter from walmart.com for $30. The inverter works fine and powers everything EXCEPT my PC. The PC will not go passed the Compaq screen. (I have an IPAQ shuttle P3 1 GHz)

So apparently my PC does not like the modified sign wave. I know the inverter is producing enough power because the overload buzzer does not turn on and I have it wired directly to the battery with 8 gauge wire. So unless there is something I am unaware of it has to be the unstable AC power. The PC boots just fine when plugged into a normal outlet. The power supply on the PC requires 3 Amps (300 watts) so 400 should be plenty.

I did not buy a dc-dc power supply because
1: it was more expensive
2: my PC needs a special 10 pin connector for the motherboard
3: I was too lazy to make an adapter for the mother board.

Now it seems that this is what I have to do....

Any suggestions on how to make the inverter work and to stop that horrible whinning noise it makes when the computer is plugged into the speakers (I have a ground loop isolator, doesn't help much)?

Can you get a DC-DC power adapter for around $30?

Any suggestions welcome?

**capcadetjc** · 05-12-2008, 10:31 PM

Im a complete noob to all this. Acutually, I haven't even made min yet. But I would expect that putting a battery backup between the two might fix it. Just a hunch.

**rybitski** · 05-12-2008, 11:04 PM

mmm... what exactly do you mean by that??

**capcadetjc** · 05-12-2008, 11:06 PM

In a home or office, you can use a back up battery power supply to protect against power outages and surges. I would expect that it would work the same way in a car.

**2k1Toaster** · 05-13-2008, 12:08 AM

Originally Posted by capcadetjc

In a home or office, you can use a back up battery power supply to protect against power outages and surges. I would expect that it would work the same way in a car.

No it wont work. Because batteries (Especially UPS's) dont like to be powered by cheap inverters either. They will never charge. And the cost of a UPS is more than a DC-DC...

@OP
So I hope you have learned your lesson. We dont just spew garbage around here, we speak from knowledge and experience. You didnt listen, went the cheap route, and now you are out the cost of the inverter and the dc-dc.

**capcadetjc** · 05-13-2008, 12:36 AM

So what your saying is that that setup wont run well right? I hope I haven't caused any trouble, just trying to help. Could you send me in the right direction for a read me of this DC-DC. Ive never heard of it.

**2k1Toaster** · 05-13-2008, 12:53 AM

Originally Posted by capcadetjc

So what your saying is that that setup wont run well right? I hope I haven't caused any trouble, just trying to help. Could you send me in the right direction for a read me of this DC-DC. Ive never heard of it.

DC-DC is short for a DC-DC Power Supply.

And inverter goes DC to AC. Then a power supply (PSU) goes AC to DC. So when running a computer off of an inverter in the car, you are going DC - AC - DC. Each covnersion is innefficient, wastes energy, gives off heat, and the DC to AC portion (the inverter) introduces nasty spikes into your car's electrical system most noticeable in audible hums or video flickering. This interference is being transfered to the electronics you are powering too. Electronics dont like that, and will die earlier because of it.

The signal coming out of those cheapo inverters is not a sine wave like coming out of your house. It is a sqaure wave or triangle wave usually. This is very messy and doesnt provide the correct power needed to charge a large battery. Hence why the UPS will never charge. You can buy a true sine wave inverter and it will work fine. But those are usually in excess of $300 for small ones.

A DC-DC on the other hand just converts the 12v-14.4v of your car to computer PSU voltages at specified voltages. Usually include Shut Down Controllers (SDC) as well.

**soloxp** · 05-13-2008, 02:24 AM

Sry to say...I use a cheap *** $10 no name 200w 400p inverter for over a yr...Running a AMD 3000+ 2 120fans 2 3.5 200g harddrives 5 usbs com port with a 200w p/s. NO PROBLEMS. I had a ELK-960 delay timer to shut down the inverter. Yes it is best to buy a real P/S. My new setup is the intel mini board, 100ghz sata hd and M4-atx p/s. You might just have a bad inverter.

**rybitski** · 05-13-2008, 07:38 AM

What type of power supply are you using?

Any suggestions for a budget dc-dc converter? My PSU is rated at 75 watt max.
12 volt 1.5 Amp
5 volt 14 Amp
3.3 volt 6 Amp

I can not seem to find an affordable converter that provides 5 volts.

I assume that I need the same amount of power that the PSU was made for because this is a special power supply design specifically for my computer. Am I right in assuming this?

When I say budget I mean around $50.

Thanks again for the help.

**Tidder** · 05-13-2008, 07:52 AM

One thing you might try is to ground the ground of the inverters output to your chassy/car's ground. This stopped a lot of strange problems when I had an inverter setup. This also stopped the whining I heard thru my speakers as well.