Inverter Question

**phatchink** · 02-12-2005, 02:29 AM

So I have a 400Watt inverter powering up my carputer right now, and there is a problem.

1. It will do a very high pitched WEEEEEEEEEEEEEEEEEEE noise after about 15 mins and it will last until I turn it off any ideas?
2. If I leave just my inverter on, will it keep draining my car's battery for 400W even when my computer is not on? Because nothing is using up the power so where could it go? I know a 400W is probably a overkill to power a PIII 666 computer, but I was hoping I could power something else if i needed it.

Any help would be greatly appreciated.

**VehicrossPC** · 02-12-2005, 03:01 AM

Ground the case of the computer to the car and it will help a little. Make suer eveything is grounded well, the ground wires are short, adn they ground in the same spot. I did this to cure the same problem, but now get a whine from an upgraded soundcard use for surround sound as opposed tosterio; sterio worked fine.

As for the power, I've already left my inverter on for several hours wihtout any problem, and it's 400 watss too. It wire actually even is used to power a reverse IR camera and 5 inch monitor, which I leave on sometimes just for kicks. Just remember to keep cables for a jub just in case, but if the computer is off you should get away with it being on for a while.

**phatchink** · 02-12-2005, 04:30 AM

Why would grounding the case help with the whining? I tried turning off the computer and the wining doesnt' stop so I'm thinking it comes from the inverter. The current inverter is wired up to the car battery neg terminal I think thats the most perfect ground u can find. I guess a better question is What Causes the Whining noise???
I left my inverter and computer on for maybe 45 minutes (car off) and the inverter light turned from green to red (meaning battery is goina be out as said in manuel) but then again I have a stock battery that has been running for 3 yrs so.... I know there'll be a day when I forget to turn off the inverter and left the car.

and I don't have a backup jump yet

**no1knows** · 02-12-2005, 06:00 AM

whining will either be from low voltage or too high temperature (more likely). Its idle consumption should be written somewhere on the box or manual...

**gizmomkr** · 02-12-2005, 09:35 AM

The inverter produces AC power - Alternating Curent. Your cr runs DC - Your pc Runs DC. The Inverters 12v and the PC's case combine those grounds together via the PSU - This connection doesnt account for or ground to the car chassis very well. The process of "Inversion" produces a lot of noise, and Your car really has no "True" ground - Your tires are rubber, there is nowhere to sink that energy.
Your alternator produces noise, and you have a good change of building up ground potential between the devices. (place a volt meter between two grounds - it should be 0, try one lead on the PC's PSU and the other on the car body ground, you will probably see 1 - 5v) That is noise, and that is bad. combining all grounds should help, but in the long long a DC - DC psu is far superior.

**Master Sadon** · 02-12-2005, 03:17 PM

666 megahertz bad luck

**grahamrb** · 02-12-2005, 05:09 PM

Your inverter manual should state the current usage with nothing connected. I use to use a 300watt inverter and I think the current usage was just under 1 amp with nothing connected.

**cavramair** · 02-12-2005, 05:47 PM

Most invertors have a fan, make sure yours is workin. Also make sure the wiring feeding the invertor is the proper size. It could be undervolting. The pc could also be drawing to much power, which would mean your drawing to much. Its most likely an alarm, now ya just have to figure out the problem.

**TundraT3** · 02-12-2005, 05:49 PM

ok guys...in terms of true ground and alternator causing noise and such...its not quite as simple as you guys are making it out to be...also, the 1-5V potential difference you measure is *not* noise assuming your measuring using the DC setting of the DMM....

you guys are correct in saying there is a potential difference between the two components but i believe u are incorrect in your summation of WHY this is an issue...

if i was setting up this system i would ground the inverter as close as possible to the ground point of the amplifiers or whatever equipment the computer output is connected to and be sure the inverter ground wire is as short as possible...if that doesnt work i have a few more easy things to try....

grounding to the battery is about the worst place to ground the inverter for this particular aopplication....

Kevin

**phatchink** · 02-12-2005, 11:07 PM

Originally Posted by TundraT3

ok guys...in terms of true ground and alternator causing noise and such...its not quite as simple as you guys are making it out to be...also, the 1-5V potential difference you measure is *not* noise assuming your measuring using the DC setting of the DMM....

you guys are correct in saying there is a potential difference between the two components but i believe u are incorrect in your summation of WHY this is an issue...

if i was setting up this system i would ground the inverter as close as possible to the ground point of the amplifiers or whatever equipment the computer output is connected to and be sure the inverter ground wire is as short as possible...if that doesnt work i have a few more easy things to try....

grounding to the battery is about the worst place to ground the inverter for this particular aopplication....

Kevin

umm what is "DC setting of the DMM...."

I thought the battery would be the most effective ground because well, gound is ground right? so I took the liberity of using 4m of wire and connecting it from the battery to the back of the trunk.
so why would extending the ground wire make it a worse ground?

So to sum it up If i want this noise to be gone I'm just going to use a short ground wire? sounds simple enough, I'm going to try it tomorrow and I'll let you guys know how it goes

o can can you tell me what some of the other easy solutions are just for refrence?