SAFE WIRE GUAGE ?

As predicted by some of you I cannot run my 20 inch box fan on high or medium for more than a few minutes before the low voltage alarm sounds. It seems to work on low for several hours. So as suggested I need to connect directly to the battery. The factory inverter DC cord is kind of a specialty cord to this unit as there are two pins that plug into the inverter from a cigarette lighter style plug. Cannot locate a specif cord with clips for my battery that has the two pins. So should I cut off the cig lighter end and straight wire to battery? Power will still go through the factory cord. Any thoughts?

The rule of thumb I use for guessing inverter draw is 10 volts
(Watts = amps times volts so if you are drawing 50 watts, divide that by 10 volts to get 5 amps) Actually works fairly well.

The light fuse is likely a 15 amp.. And the wire is likely proper for 15 amp if you are adding 12 volt outlets, you may get the Flash (from the fuse) of Darkiness (from the lights) You may wish to upgrade.. I added some 12 volt outlets to my RV, but let's just say for most of 'em I went LARGE on the wire. Two are hooked to lights, one to a motor lead (I did not go large on those) 3 are original wire back to the fuse box. 10ga, 20 amp fuse, 20 amp rated outlets.

Oasisbob wrote:
Is there a problem with running an extension cord from the inverter to the fan? Thanks guys

Just don't make it a trip hazard.

No reason to not use an extension cord with the 120 volt outlet of the inverter.

No problem with using an extension cord and lengthening the AC output of the inverter. I'd bet you're going to run into issues using the light circuits and powering the inverter. If you have LED's replacing the incandescent bulbs, it will help.

Using the above stated draw numbers of 10 amps for the fan, it will not take many incandescent bulbs to exceed the fuse rating, even if it is 15 amps. The inverter draw will not be linear, either. It is a dynamic number because of the 12V voltage fluctuation.

Thanks to all who have contributed on my original post. Sounds like if I am over loading a curcuit I will blow a fuse? Also sounds like it might be safer to connect as close to battery, or battery direct. One more question. Is there a problem with running an extension cord from the inverter to the fan? Thanks guys

Looking at a number of box fans, the biggest draws 110 Watts on high speed (most draw much less).
That will mean your inverter will draw about 10 Amps to run it - worst case. It's probably closer to 5 or 6 amps.
The wiring in your RV will be fine with that small amount of load assuming nothing else on the circuit draws much.
Normally the circuits in RV are protected by a 15A fuse and the wire is completley capable of supporting that.
So your fan should not be a problem if your running it on the stock wiring.
Relax and enjoy.

Hi

If it is OEM wiring it will already be fused.

But you may waste lots of amps by pushing the circuit too hard.

Better to keep the inverter as close as possible to the battery bank and use the largest size wire you can on the DC side, properly fused.

I think your inverter is going to squak at you as soon as you turn the fan on. The wiring in your rig will not support the current needed to run your inverter and fan. As others have said, wire the inverter within a foot or two of the batteries. I'd use at least 6 Ga wire. You can then figure out how you want to deliver the inverter power into your rig. Either an extension cord, a special outlet that just runs from the inverter, or a transfer switch to power the whole rig (very technical to install this way).

All installed wire should have a proper fuse. Fuse should open before the wire burns up.

Your concerns should be low voltage and loss of power when using a shared or undersized circuit.