Adding Another 12V Circuit

[TravelingRae]

To install my upgraded converter yesterday, I had to change the DC board and noticed that there are several empty circuits left on the board.

My biggest power management challenge is charging my Macbook Pro. Doing so through the inverter is difficult. I have better luck charging it with a 12V charger, avoiding the DC to AC back to DC conversion of power.

I am experiencing enormous voltage loss to the outlet where I charge the computer. I've calculated that I would need to run 8AWG cable from the batteries to a dedicated outlet to eliminate that voltage drop, which will likely be a 30' or longer run of wiring.

I'm now wondering if I could instead run a new line from the DC electrical panel to the outlet instead, a run of just a few feet. My thinking is that the main power cable going from the batteries to my power centre is very low gauge (looks like at least 8AWG), and then I could run smaller gauge wiring the rest of the way to an outlet.

Would adding the new circuit be doable or a no-no? I have a 30A rig and the converter is a 45A model (same as my old one) with each circuit being able to handle a 20A load.

Thanks,

Rae

[Harvey51]

Five amps for the Mac should not cause so much trouble!
I added a new DC outlet right in front of our converter/DC fuse panel using 14 gauge lamp cord on a previously unused fuse. No problem charging laptop using 100 watt plug in inverter or iPads from 12V USB adapter..

We also find it handy to charge phones from the dashboard outlet when driving or camping.

[pianotuna]

Hi Rae,

At least it is not 40 C outside!

[TravelingRae]

Well, there goes my next Saturday. 🙂 Thanks for your input!

Rae

[westend]

Yes, you can establish a new DC branch circuit from the DC distribution panel. You will want to make sure that all wire gauges supplying the power to the fuse location and distribution panel are able to handle the additional load and that the new branch circuit wiring is sized correctly for the amount of current and length of run.

[TravelingRae]

Yup, that's what I've figured out, too, but that doesn't answer my original question. 🙂 Do I absolutely need to run wiring directly from the batteries to an outlet or can I start from the DC board by adding a new circuit?

Rae

[pianotuna]

Hi Rae,

I guess you need thicker wire or else there is a poor connection.

[TravelingRae]

The circuit draws 5A. By enormous voltage drop, I mean that if my batteries are fully charged and showing 14+V midday, plugging in the laptop will drop my voltage down to around 12.2V. In the evening, with voltage starting at 12.6, I get drops below 10V. Not normal!!! This is on all my DC outlets, both ones that I have installed myself and those installed by the manufacturer.

I am going to confirm the gauge of wire between the converter and the batteries, but I strongly suspect it could be beefier.

Rae

[pianotuna]

Hi Rae,

How many amps does the circuit draw?

Voltage drop and DC is a fact of life.

By enormous voltage drop how much do you mean?

[popeyemth]

Change the outlet out for a new one and clean the wires good and bright before you connect it

[tvman44]

Yes, but I would put larger wire from converter to battery. #8 is a little small. 🙂