Wire Size charts

[BradKW]

Due to battery placement and desire to keep electrical components in the designated area, I'm looking at about a 15 foot run between 24v batteries and both the 24v inverter and the charge controller. 

On the voltage drop calculator, I'm seeing a loss of 0.25% at a 15' distance @ 24v @ 20 amp load with 1/0 wire. That sounds very good to me...perhaps good enough that I can go lighter gauge? 2 awg would still only be 0.39% with same specs. The 20 amp part is kinda made up because I don't know the answer, but 20 x 24v = 480 watts and my AC is only 430 watts, so that sounded good?

For the charge controller, I don't know what numbers to plug in...say 1000 watts solar, but its filtered through the CC, so...still 24v going to battery (or about that), don't know amps since it varies with sun...

While a 0% drop would be nice, in reality what % drop you think I should shoot for, balancing wire cost with efficiency? Seems to me 1% might be ok, and let me use 6 awg I think...

 

[Optimistic Paranoid]

You know if you're 15 feet away, you have to use 30 feet in your calculator.  You need to allow for the return wire as well as the hot.

The rule of thumb is to mount the inverter as close to the batteries as possible.  The DC wires should be as short as possible, the AC wires can be as long as you want without causing any problems.

 

[BradKW]

I did not know that about the return counting in.

I do know the rule of thumb, and am really wanting to go against it because moving the batteries to a forward under-box mount isn't convenient to move inverter there. My thinking is that one benifit of 24v is I can get around the general rule without having to use absurd wire size. At 30', 3awg is a 1% drop...

 

[SternWake]

The main benefit of higher voltage is thinner wiring required.

I'd keep the solar charge controller to battery, and inverter to battery cables thicker.

On the solar controller this will allow it to get the batteries to absorption voltage earlier and hold it longer meaning happier batteries.

On the inverter it will mean longer before the low voltage alarm on the inverter starts screaming. But that later scream is allowing a deeper level of battery discharge.

 

[Mobilesport]

I didn't know you had to count the return wire either , after all these years , good thing I always run oversized wires on everything

 

[jimindenver]

I know this, not everyone agrees on size. I just bought a bunch o pin lugs that are suppose to be 1/0. There is no way my 1/0 cable will fit in them so I am glad I haven't packed the drill press yet.

 

[MikeRuth]

It's early and I don't recall exactly but I found wire calculators that factored the return or Total amount of wire used. Check the specs of the calculator.

 

[BradKW]

It's early and I don't recall exactly but I found wire calculators that factored the return or Total amount of wire used. Check the specs of the calculator.

Thanks Mike, I will look into that. Hey, I was browsing your blog and came across what looks to be a pic of a automatic battery filler of some sort...which was just a topic in recent S/G testing thread. I'm going to post a pic of it there, hopefully you'll comment