Inverter Question

Xanadu1979 · 01-26-2004, 12:31 AM

If you use an Inverter and it is connected directly to your batteries positive terminal, won't the inverter always be on until the battery dies?? How do you handle switching power off and on to the inverter if you go that route??

Thanks Again,
Landon

Xanadu1979 · 01-26-2004, 12:33 AM

does the inverter draw power from the battery if the things connecting to it aren't on??

telstargb · 01-26-2004, 12:40 AM

most inverters have an inbuilt on/off switch

ELEmental59437 · 01-26-2004, 12:43 AM

wire a relay to the ignition wire to only allow the inverter to be powered while the car is on.

Xanadu1979 · 01-26-2004, 12:59 AM

how big should the relay be? I'm guessing that this relay is connected to the wire connecting the inverter to the battery. Has anyone had problems connect 8 gauge wire to a relay?

Thanks, I apologize that I'm so clueless.

-Landon

Xanadu1979 · 01-26-2004, 01:01 AM

ok, I rethought some things, I should get a 12 V relay. Can someone post a link to a relay I should get?? Now my only issue is how to connect the 8 gauge wire to it and finding where the ignition/acc. wire is. Any thoughts?

Xanadu1979 · 01-26-2004, 01:22 AM

The Inverter that I have has an on/off button. Could I wire a relay to that from the ignition switch??

robiewp · 01-26-2004, 01:25 AM

Quote: Originally Posted by Xanadu1979

The Inverter that I have has an on/off button. Could I wire a relay to that from the ignition switch??

you could, but I don't know why you would want to.

I'll give you a link to a recent topic i responded to...

here:
http://www.mp3car.com/vbulletin/show...ighlight=relay

Xanadu1979 · 01-26-2004, 01:40 AM

so I guess my only issue now is how to physically connect the 8 gauge wire to the relay. It just seems like it would be tough as the connectors are small (Maybe I'm just dumb). This is the way I have it in my head:

Battery 8 gauge wire(positive)-----------relay--------8 gauge wire to inverter
l
Acc. fuse

Thanks again for all your help, I'd be going crazy without ya!

robiewp · 01-26-2004, 01:44 AM

8 gauge is a little fat but not too fat for a crimp on connector IMO. You'd be fine with 14 gauge from the relay to the inverter if it's a short distance.

Xanadu1979 · 01-26-2004, 01:48 AM

Cool, well I think I understand it know. I wasn't able to go to sleep because I got to thinking about how I would turn the inverter on and off. I'm just waiting for parts to get here now. I'm guessing that an Opus setup would use the same relay setup for on and off. My only issue there is how to power things like USB hubs, my touchscreen. If all these devices require 12 v could I just hook them all up to the same relay??

Xanadu1979 · 01-26-2004, 01:49 AM

I thought I was up late, I'm in Dallas (12:50 am). I just realized that you're in Mass. Thanks man, you have REALLY helped me. You mind if I tap you again if I need to?

robiewp · 01-26-2004, 02:30 AM

sure, no problem. Philosophy was keeping me up anyway, and the forum sends me emails (which I perpetually check) when there's a new message in any topic I've posted in.

As far as hooking up additional devices, you should keep in mind that a car actually outputs (with some regularity) 13.8v, so if a device claims "12v", it might be a bad idea to run it off of the car battery. If you're running an ATX supply though, you can get 12v and 5v off of a molex connector. Another alternative is to find a car adapter from radio shack designed for a certain voltage device. This is how I power my USB audigy 2NX and USB hub. You could power/switch this (or anything else for that matter) off of the relay.

robiewp · 01-26-2004, 02:40 AM

I just realized you had a few more unanswered questions. You can find appropriate relays at pretty much any auto parts store. Should be under 5 bucks for a 30 amp one, which is plenty sufficient.

Regarding hooking this up, it's good to have a fuse near the battery too. I didn't understand this until it was explained to me (thanks dodgecummins), rather just following it blindly as convention.

Quote:

The fuse protects the vehicle wiring. The farther the fuse is from the power source, the more likely damage or a short circuit will burn up the wiring.

If the fuse is right at the battery, then a short will blow the fuse...with no damage.

If you have 20' of wire, and you get a nick in a wire along the way, between the battery and the fuse, the wire will continue to try and conduct the electricity until it glows red hot (like a light filament) and sets the interior of your car on fire.

In my first REV (no tank) I ran a fair gauge (4) wire from my battery (fused 12 inches from the battery) to my trunk, then used a fused break out box to bring the wire down to a more manageable size. Wire to my amp was 8 gauge, and wire to the relay and then inverter are 14.

what size inverter do you have / what all are you powering? 8 gauge from the battery is good because of the long distance, but I think you can without ill consequence settle for something smaller from there. Any place there's a break in the wire (fuse, relay, or breakout) would be a good place (in my opinion) to do this.

Rob

Xanadu1979 · 01-26-2004, 02:52 AM

I'm just gonna run the pc, external HD, external slim dvd, USB hub and 7 inch touchscreen. I've got a 350 watt inverter but I don't mind getting a bigger one if that won't do it. So you're saying, run 8 gauge to a block, run 12-14 to the inverter with the relay in between. Is will I need to run a long wire from my fuse box or ignition wire to the relay or should there be something in back I can tap into? Would you recommend a fuse tap into 12v source for the relay? Would there be a limit on the length of wire carrying that 12v to the relay?

Thanks,
Landon