Cable size

[asdex]

Just wanted to check, I have a wind generator 35 meters from the house. I have replaced the 12 volt one with a 24 volt one. It has 2AWG (25mm2) cable running to the house. The 24 volt one only needs 7AWG (10mm2) cable. Could I extend the cable by 6 meters with 9AWG (6mm2) cable as I have moved the battery bank. I'm expecting the oversize 35 meter cable loss will help compensate for the higher 6 meter cable loss so they will balance themselves out a bit. The generator doesn't worry about voltage drop.
Thanks,

[Sunking]

Why are you asking? Just use a Drop Calculator.

Enter the working voltage say 36 volts. Min required for 24 volt battery

Enter percentage of voltage drop 3% or less. 2% is standard practice.

Enter max current say 20 amps

Enter 1-way wire distance say 115 feet. (35 meters)

Ignore cable type

It will tell you need 2/0 AWG or 133100 circular mills, or 67 mm^2 cable. aka 11 mm diameter

WARNING TO ALL:

Distance of 6 feet or less will result in a cable to small to safely handle the current. In that case you use NEC minimum. Example at 20 amps is 12 AWG real cheap 12 AWG.

[asdex]

Thanks, I tried the calculator and it says 8 gauge. I hadn't thought of using any voltage other than 24 since its a 24v generator so thanks for that. The 400w comes to 11 amps I calculate.
So as I need 8 gauge but the majority is in 2 gauge, I wonder if I can get away with 6 of the 42 meters in 9 gauge?
Would I just do the calculation for 35 of 2G and 6 of 9G and add the percentages of voltage drop together?

[asdex]

I have tried the calculator and it doesn't match with what the turbine manufacture says. I have attached their cable specifications for 150 feet and its 8 gauge when the calculator says 2 gauge.
I suspect either my current or voltage figure is incorrect.

[SunEagle]

I have tried the calculator and it doesn't match with what the turbine manufacture says. I have attached their cable specifications for 150 feet and its 8 gauge when the calculator says 2 gauge.
I suspect either my current or voltage figure is incorrect.

The turbine data may be using a different voltage drop % then the calculator. Or as you suggested a different voltage and current rating.

[Sunking]

What voltage and current are you using. You use actual voltage and current. What kind of controller? . I have no idea what voltages and current your turds use, or what percentage the manufacture is using.

The voltage, current, distance, and percentage you enter are critical. The lower the voltage is, the size of the conductor is going to shoot up real fast. Quick example and you will understand why a PWM Controller is crap.

Lets say you have a 24 volt battery, 1000 watt panels, panels Vmp = 40 volts, Imp = 25 amp, one way distance = 100 feet. The first mistake you would likely make is using 40 volts which is an error. The voltage you have to use on a PWM controller is 1 volt higher than the battery or 25 volts. The batteries will pull down the panel voltage. So if you used 40 volts you come up with 2/0. The correct answer is 3/0 using.

But what if we used a MPPT controller? Wired the panels in series for 120 Vmp. What happens. Well for one we use 120 volts and 8.3 amps. Now all the sudden we only need 10 AWG wire. Care to guess the difference in price of 10 AWG vs 3/0. If it were a PWM system you only 600 of the 1000 watts (25 amps x 24 volts = 600 watts. With MPPT once you factor in power losses in the wire and controller you get 950 watts out of 1000 watts. That $50 PWM controller becomes a heck of a lot more expensive than a $500 MPPT controller. Instead of saving $450, it cost you an extra $2000 in wire and extra panels

Pay attention to details, it matters. That is one reason I am so hard on folks. They do not think or know what is going on. I am just trying to save them a lot of money and be safe. Ignorance is terribly expensive and how you get stuck with Biliary and Chump the Pootey Snatcher for choices.

[asdex]

Hi, thanks for the explanation on controllers. As I don't really know the output specifications of the wind turbine, I'll have to go with the manufactures specifications on cable. The Air-X turbines have an inbuilt controller and I'm sure it will be PWM. You can wind the voltage to max and use an external controller which I may do later.
I might send an email to Primus the owners of Air-X and see what the output specs are.
Cheers,