Thread: Another inverter question...for electronics gurus

Originally posted by moahdib:
<STRONG>Since I am not that great in electronics I gotta question:
I have a 300W Inverter and my computer power supply is 150W. Does my inverter need to be wired with thick wires just bc its a 300W? I know the computer will never consume more than 150W...
I am thinking of redoing the wiring bc the invverter dies sometimes... using 8 gauge wire running 12feet, fused with 30A and a switch to cut the power on and off ( 12V@20A rated rocker type switch) is this a good idea??</STRONG>

I run 15A auto cable (about 3mm think in diameter - not including insulation) to the inverter. It is a 120W Jaycar model (aust. company) and it is running a 300W ATX PSU.

The computer is a Duron 800MHz, ASUS MB. 8 Gauge is a definate overkill.... but if you arent running the inverter directly to the battery at the moment (using the cig lighter,etc) I would be trying that first.

Hmmm but im running the 8 gauge all the way to the trunk ( about 10 feet or so ). I was also thinking about powering up my bazooka subwoofer ( 200W ) by adding a distribution block.

Distribution block sounds good, but I would use a relay on the inverter that way you wont have 8ga wire going under your dash to some switch, you can just run 18ga wire from the switch to the relay and let it handle the load. And 8ga should be fine.
Steve

I will tell you how to do this, but you sacrafice the warranty on your inverter.
Most inverters will not come back on after having the electric cut off to them by using a relay, so..
1. Unscrew the inverters front panel and look for the wires running to the switch.
2. Cut the wires, and use 2 wires of similar gauge, attach them to the old switch wires, use solder and Wire nuts, and run it out the front panel (Be very careful, there are big capacitors in there)
3. By a small toggle switch and mount it in the dash of you car, run the wires to it.
TADA

And, use atleast 8-gauge. Come on people, I mean the wire is cheap! use it! Hell, I used 6 gauge, but I have a 600 watt inverter.
You can never have enough, but you can have to little.

And in awnser to your question, no, the inverter will only draw as much power as it has to, but initially, when you turn it on, it draws even more than 300 watts to charge its capacitor.

Theres only one problem with that, some inverters (like mine) only cut the output off (110vac) and leave the inverter in idle mode which draws about 2/10's of an amp. Now I know this doesn't sound like much, but over night it could drain your battery so it wont start (I know it happend to me and yes my battery was in great shape!)
Steve

Originally posted by lstrunk:
<STRONG>2. Cut the wires, and use 2 wires of similar gauge, attach them to the old switch wires, use solder and Wire nuts, and run it out the front panel (Be very careful, there are big capacitors in there)
</STRONG>

Huh? Large capacitors? So what. They're charged to 12V.

And, use atleast 8-gauge. Come on people, I mean the wire is cheap! use it!

Uh, 14AWG is significantly cheaper than 8AWG, and much easier to run.

Hell, I used 6 gauge, but I have a 600 watt inverter.
You can never have enough, but you can have to little.

For most people, running wire this thick would be very annoying. Thinner guages are cheaper, and easier to install. Also, the connectors at each end are cheaper, and it is much easier to solder thinner wire.

Wouldn't there be capacitors to filter the output of the invertor (i.e. charged to mains voltage)? Or do they just rely on the input being filtered to give a good output signal?

Originally posted by Aaron Cake:
[QB]Huh? Large capacitors? So what. They're charged to 12V.QB]

I think he means the ones on the internal high voltage DC bus. They could be charged to 200v or something..

Large capacitors? So what. They're charged to 12V.

Even 1 volt could kill you with enough ampreage. It doesn't sound like you really should be messing with anything electric.

14AWG is significantly cheaper than 8AWG, and much easier to run.

Whats the big difference, you still have to pull up your carpet, and everything?
And if you can't afford the 10 cents extra a foot for good wire, you shouldn't be doing this project.

Also, the connectors at each end are cheaper, and it is much easier to solder thinner wire.

What are you soldering it for?
On the back of my inverter atleast, is just two boxes you stick the wires in, and screw clamps down on them.