Inverter Relay Question

**thunderdepot** · 11-25-2006, 09:28 PM

Ok I am tired of turning on and off my inverter every time I get in and out of my car.

So it is time to get get a relay to make the process automatic. I just want to double check with the great mp3car power gurus. I know nothing about electrical stuff just hardware and software. I don't want to mess anything up on my car or carputer.

Check out the diagram below. Basically I want to leave my inverter's switch on and then use the relay to give the inverter power when acc triggers it and take away the power when I turn off my car.

And before you tell me that inverters are terrible I know but they are the best for my dell laptop setup.

Do I have the correct setup for what I want to do? What do you reccommend? Where should I put fuse(s)? Is 8ga wire good enough? What ga for ground and acc?

Thanks for the help!

**com2soft** · 11-25-2006, 11:06 PM

auto start may be o.k. but when acc is off it will kill the inverter power immediately so only hard power off to the computer.

**thunderdepot** · 11-25-2006, 11:47 PM

Originally Posted by com2soft

auto start may be o.k. but when acc is off it will kill the inverter power immediately so only hard power off to the computer.

It is a laptop so I have it set so when the battery power gets to a certain level it goes into hibernation. But this is just in case I forget to use the hardwire switch that I have connected to my laptop.

The hard wire switch will wake it up from hibernation or put it into hibernation or turn it off.

Other than that does everything look fine?

**dupa2** · 11-26-2006, 12:43 AM

I think that it requires little bit of electronics to drive the relay. Once ACC signal goes to 0V, it should give about 30sec delay before shut off, but it should send ACPI ( 5V to 0V edge) to laptop (power line) to shut it down or hibernate before the juice cuts off. Such thing can be programmed into one of processors (ATMEL, 8051, 16FXX) but it requires little electronics skills. If you basically want to cut the power off the inverter, use 12V relay, but it may corrupt some filesystems like FAT or NTFS, if you use ReiserFS or Ext3, more or less yo're just fine to do it.
If you need any help with this problem, just PM me.

**billmee** · 11-26-2006, 07:40 AM

It would be cheaper/quicker/better to use a small relay to replace the on off switch of the inverter.

In my setup I pulled the small wires off the switch and connected them to a $6 automotive relay from Autozone. My ACC and 12volts from the pc both energize the relay thru some 1n4004 diodes for simple isolation.

If you want some more details let me know,.

**thunderdepot** · 11-26-2006, 11:04 AM

Originally Posted by billmee

It would be cheaper/quicker/better to use a small relay to replace the on off switch of the inverter.

In my setup I pulled the small wires off the switch and connected them to a $6 automotive relay from Autozone. My ACC and 12volts from the pc both energize the relay thru some 1n4004 diodes for simple isolation.

If you want some more details let me know,.

Yeah give me some more details but it sounds more complicated.

**billmee** · 11-26-2006, 04:22 PM

Originally Posted by thunderdepot

Yeah give me some more details but it sounds more complicated.

First fuse the wire as close to the battery as possible.

Most posters will recommend 8awg wire but I used the existing 14awg cig lighter cable -no problem for 100 watts.

Mount the relay very close to or on the inverter.
Run the inverter power switch wires to the relay.
Supply the ACC signal to one end of the relay coil thru a 1n4004 diode (silver stripe at relay end).
Supply the 12v hd wire to same end of the relay coil thru a 1n4004 diode (silver stripe at relay end).
Connect other end of relay coil to ground/chassis.

I could take a pic of the car setup if you are interested...

**thunderdepot** · 11-26-2006, 05:25 PM

Originally Posted by billmee

First fuse the wire as close to the battery as possible.

Most posters will recommend 8awg wire but I used the existing 14awg cig lighter cable -no problem for 100 watts.

Mount the relay very close to or on the inverter.
Run the inverter power switch wires to the relay.
Supply the ACC signal to one end of the relay coil thru a 1n4004 diode (silver stripe at relay end).
Supply the 12v hd wire to same end of the relay coil thru a 1n4004 diode (silver stripe at relay end).
Connect other end of relay coil to ground/chassis.

I could take a pic of the car setup if you are interested...

Why is the pc in the picture? I have a laptop setup with a hard wired switch to turn it on.

Yes it would help to have a picture.

BUT what I basically want to know is will the setup I have pictured work? All I want it to do is supply power to the inverter when car is on and cut power when car is off. To accomplish the auto turn on for inverter I will leave the inverter power switch set to on. Is there any problem doing it this way?

**billmee** · 11-26-2006, 06:00 PM

Sorry forgot about the laptop bit.

Yes your setup will work.
If the original pic had a fuse it would be perfect.

My suggestion to add the hd 12v just allows the relay to operate while the pc is on the the acc signal is off, like when you are shutting down and want the pc to turn off the inverter.

**thunderdepot** · 11-26-2006, 07:01 PM

Originally Posted by billmee

Sorry forgot about the laptop bit.

Yes your setup will work.
If the original pic had a fuse it would be perfect.

My suggestion to add the hd 12v just allows the relay to operate while the pc is on the the acc signal is off, like when you are shutting down and want the pc to turn off the inverter.

Where should I add a fuse at?

Other than that my setup should work perfectly?