Fuse keeps blowing on cobra 400 watt inverter

Is the fuse in the inverter or is it in line near the battery? How many Amps is it? You should have a 30 amp fuse for 400 watts if the engine is running. If the battery gets down closer to 12V from being turned off, the requirements increase slightly towards 35 if running full tilt.

W / V = A

400 / 14 = 28.5

400 / 12 = 33.3

Also, you only get the 400W if attached to the battery. In the lighter socket you get maybe 100 to 130W.

 

The cobra 400 watt inverter will work, but the cigarette cord lighter that it comes with is awful. It can't handle anything. I threw mine away after hooking up the cord from my older inverter to it and it worked fine after that. I think the cord with the lighter plug that Cobra is supplying isn't high enough gauge wire to get the job done. Try getting a thicker one.

 

You can only pull 180 from a lighter plug socket there by under driving the inverter causeing internal heat.
If you hardwire the inverter is will work just fine,but under driving it with low amperage is what killing the fuses.

I run a Inspiron 1720(19.5 volts) off a Black&Decker 100watt(115voltAC)and have for over 2 yrs without any issues.$10-$15 # WalMart's

 

My laptop (XPS M1730) has an X9000, 2 hard drives, 4 gigs of ram, and a gig (2 x 512 8800m) video cards. The brick says on it that it draws 230 watts, and that the amps required are 4.

If I plug this thing into a 400 watt inverter, it will blow fuses like nobody's business, connecting it straight to the battery instead of running through a lighter socket is required to power anything that draws any kind of decent current (no, we aren't talking about the 1720 with it's baby power supply). HOWEVER... once I did that with a 400 watt inverter, all it did then was turn itself on and off tripping the thermal protection over and over.

The reason is that the 400 watt inverters only put out 3.85 amps, and it just isn't enough to power these big suckers (your gateway is almost identical to my Dell).

Pick up the CPI875 inverter instead, it pushes 7 amps, and will run MUCH cooler than the 400 watt model with the computer on it. Yes, you will have to wire it straight to the battery, and there really isn't another option other than getting a lesser model computer.

 

I used 2 cobra cpi450 400watt inverters with a dell XPS2010 for over a year and was fine, all I did was stopped running 15amp fuses and started running 20amps and I was golden I also had the next size up I think it was the 875 and hooked that up on top of my CB directly to the 12 volt power source...