Yeah yeah! That pic looks right in my '12! It's the same as wiring to the - side of the battery! I saw that.

Pedro_Dog - You've been VERY helpful! I understand the whole voltage x Amps = watts concept, but I didn' think to do it the other way!!! 47 Amps is a TON! I have HEAVY DUTY jumper cables that I need both hands to open that is a 0 gauage wire and it says 65 Amps max. I started doing some math too and maybe I might be okay with the 150w inverter (minus my breathing machine of course because the 300 watt barely handles it)

Laptop = 16V/5A = 80 watts - no problem
Battery charger for tools = 19v/3A = 57 watts - no problem
RC car charger = 7.2V/4A = 29 watts - no problem
Cell phone charger = 5V/1A = 5 watts - no problem
Dyson vaccuum charger = 16.75V/348mA = 6 watts - no problem
Even a BRIGHT shop light = 100 watts - no problem

So this is cool!

 

Right yes forgot about that connection point! (shows you how much I am actually under the hood of my truck haha!) I thought you were talking about hooking directly into the fuse box, and working through the connections in there, my bad...I have never really thought about doing aftermarket connections to there, I have just always gone to the battery. I do however only run a single wire from the battery back to a separate distribution panel controlled by a relay. This way all my aftermarket electronics are all controlled off this new "fuse box" per say. Its also tucked under the dash so there are less wires going through the firewall. Its a good idea tho! I will have to keep that in mind if I ever do any electric mods that do not require wires to go into the cab!

Also to add on the reason why you can use smaller wires (correct me if I am wrong) In an AC system, the current only flows through the center of the wire, not the whole conductor. This is known as skin effect, and it varies by conductor type and frequency. Basically it creates a lot of resistance, and can only be found in AC systems. Where as DC (what your car is) does not have this skin effect, so the current flows through the WHOLE conductor, thus having less resistance and less heat! Just a little thought for those who were wondering why!

 

i think you should still go for something a bit bigger than 150w. you will most likely have to run a wire form the battery or PDC anyway so better off to spend the money right the first time on something you can use for everything that you will need. plus i find those small ones get hot when they start being used near there max wattage rating. i bought a 1000w one for my truck just so i could run pretty much whatever i need when i need it.

 

Actually, the skin effect of AC is due to the current density being greater on the "skin of the conductor", on the outside, not the inside of the wire. The higher the frequency the more pronounced the effect is. For most purposes however, it has no effect. At 60 Hz, the depth of the skin is 8.5 mm in copper. since an inch is equal to 25.4 mm, then the skin depth is about 1/3 of an inch all around the wire, so unless you are running a wire that is bigger than 2/3 of an inch thick, the skin effect doesn't come into play. It is interesting to talk about it though.

 

yes thanks for correcting me! That is what i meant...i should re-read my posts...

 

The inverters in our trucks, simply put, convert 12VDC to the 117VAC like the AC power one gets from the wall outlet at home. They do this electronically - primarily by switching transistors or FET’s on and off at a particular rate or frequency. You don’t get something for nothing and in the process a little of the DC is actually used to power the inverters circuitry. Generally the efficiency is fairly high however and not a lot of energy is wasted in generating heat. I could go on about efficiency ratio’s, switching frequencies, FET’s Versus Bipolar, THD, PWM, flywheels and all sorts of supporting formulas but that’s beyond the scope of our Dodge Forum. If anyone would like more acute information along these lines PM me and I will be happy to go there. For now just know it’s an electronic circuit, nothing mechanical in there. So no amount of external wiring or fuse changes is going to significantly alter the inherent capabilities of the circuitry just described, you simply have to move up to a higher power unit.
The early “square wave” units produced a form of AC but it was really more of a (dirty) square wave generator. The distortion or harmonic content of these inverters can play havoc with ac loads, particularity ones inductive in nature such as motors and transformers. If you ever tried to use one of these to power a radio or TV you would find the noise or “hash” produced to be quite intolerable. I once tried using one of these things to power a small TV in my camper; the lines of interference on the screen almost completely obliterated the picture. Improvements in technology have yielded “Modified Sine” units like our trucks have and also the “Pure Sine” inverters. The modified square wave inverter spends more time around 0 volts which gives it more of an AC crossover point. These units are more compatible for all but the most sensitive types of electronic equipment such as audio and RF communications. For these cases, “Pure Sine” inverters are really the only way to go. With their very low distortion, Pure Sine units are really more of a power oscillator than an inverter. Their output is the closest approximation to what you get from your wall outlet. Of course they are the most expensive of the group. As for skin effect, there really isn’t anything going on in our trucks power system that is high enough in frequency for this to be of any real consequence. When you get to radio frequencies then skin effect, along with a whole other host of phenomenon, becomes very significant. I get to deal with that stuff every day.

 

It neverr hurts to over engineer electricity!

 

Also if you have the center console you have a ton of room to put it.

 

OK Silly question???
When you mention the inverter power rating (150W, 300W, ect) is this the "AC" power rating or DC??

When this is calculated for current/fuse requirements does it matter?

for example:
P = I * E
DC : 300w = I * 12v so I = 25A
AC : 300w = I * 120v so I = 2.5A

Does the 2.5A AC equate somehow to 25A DC??

Thanks for some further insight :-)

 

It's for the load side of the inverter, in this case the 12VDC wires need to be able to handle the 25 Amps ( a little more to account for the efficiency of the inverter plus the electronics controls and fan). The output side can handle the 300Watts (the load) so the wire needs to be able to handle the 2.5 Amps.

As far as the question of AC current vs DC current, current is current (electrons moving from load to source - they run in opposite direction to the current). It's a little complicated to write about it here.