I attach my inverter with custom battery cables and it powers up. As soon as I plug in an extension cord (any cord)it starts beeping. I don't even have anything plugged into the other end.

you will still need power supply, you can attach it to extension cord,

replace batteries

You open the door that covers the plug on the lower side and find a extension cord and plug it in and then in to a wall outlet for about 24 hrs

When you plug in the power cord is there any lightswhatsoever on the laptop, where the plug goes in or on the AC Adapter of thepower cord?

When you press the power button do you hear fans running, hard drive spinning,lights on the computer, hear any beeps or lights constantly blinking, hear theDvD/CD drive click and the light on the drawer of the DvD/CD turn on for asecond or two? If so the laptop is trying to boot or may have booted, butthe screen is not showing for some reason.

Beep tones and blinking lights tells the technicians what is going on with thelaptop and why it is not booting. Most times it's a motherboard issuewhen you hear beeps or blinking lights continuous.

Maybe your power cord is bad if you don't get anything to happen whatsoeverwhen you press the power button. And if that's true maybe you wasoperating off the battery the last time you had it on and since the power cordis bad, it was not charging the battery so the battery is drained and the powercord is bad.

Maybe you have a Static Charge Buildup. Remove the Power Cord, Remove theBattery, then Press and Hold the power button for 30seconds. After 30 seconds plug the power cord back in (leave the batteryout) and hit the power button to see if it boots. If it does, you can putthe battery back in and let it charge.If it seems like the laptop is up and running but the screen is not displaying anything then the issue is with the screen. Take a flashlight and shine it on the screen and look very hard and you might see the icons or something very faintly on the screen. If so, your LCD Inverter needs to be replaced. It is located at the bottom of the screen and covered by the strip that goes around the screen. IIf you don't see anything on the screen then try plugging an external monitor to the laptop. I can be any kind of monitor, even the old big fat crt's as long as it has a vga cable that can go into your laptop's vga port. If you see the image on the external monitor, that means your video card is good and the screen needs to be replaced. Sometimes you might have to hit the FN key plus one of the F1 thru F12 keys to get the image to display. The correct F1 thru F12 key will either say CRT/LCD or it will have the icon of a display on it. Press and Hold the FN key then hit the correct F1 thru F12 key. This will toggle the the image to display either on the computer's screen, the external monitor screen, or on both screens.

Test your PSU or replace it if your power supply units fan is not working your PSU is faulty

One bad lead can cause a computer to continue on a cycle or to shutdown or fail to detect/ boot up a computer hard drive

Test all leads that attach to your hard drive including electrical extensions,IDE,SATA

the leads from your ((motherboard to your hard drive)) make sure they have a secure connection and are not faulty or just replace them there probably old and faulty
make sure all leads that are attached to your drives dvd\cd 3 1/2 inch floppy have secure connections and are not faulty even the electrical extensions or just replace them they are probably old and faulty a computer needs its connections to have an end so any faulty leads will end up with a computer error

hope this will help
don

I looked at the power requirements of this projector, 280W, but that assumes a nice sine wave. Your inverted is supposed to put out 400W, but it's a modified sine wave. Under ideal conditions (including a good battery) this might be just enough. Connecting directly to the battery will help a little, because of the limited ability to get current to and through the cigarette lighter. Using a 100 foot extension cord will diminish the voltage a bit (less so if it's a heavy gage wire). I would try connecting the inverter directly to the battery, run the engine and skip the extension cord. If that works, turn off the engine. If that works, try the extension cord. If it won't work with the engine running, connected directly and no cord - there are two possibilities: (1) the projector just won't run on a modified sine wave, (2) you need a bigger inverter. --- regarding (1) I have seen lots of people having trouble with various devices. You might want to ask Epson support. --- Good luck!

it is possible the alternator's power is higher than that of the inverter ,that is overload

Where can I download Instruction manual for Fuji FVR-E7S?

When you attach the phone lines, the line coming from the wall must be put in the "L" (line) jack on the machine. The extension phone can be plugged into the other jack. If you have the line coming from the wall to your phone first, and then the extension line coming to the machine, you will get the beeping. You must have two lines plugged into the machine.