getting the correct cable gauge.

[CAP]

hi i have a 18 v 32.5 amp approx 583 watt system ,with 9 panels and 65 watts each. the distance to the 12 volt bank is about 13ft to the closest panel. Would 6 awg wire be good enough without too much power loss? also the wire coming from each panel is smaller (12 or 10 gauge ) is that a problem?
and what gauge wire for my battery bank? ,will probably be 2 230amp hour 6volt golf cart batts in series, will these charge too fast?possibly damage them.
and one more thing, I know this is a lot of questions at once and this i Is not the best question, but If I wanted to use 2 12 awg wires wraped nicely would this be sufficient (with insulation) . Or should i just buy the 6 awg

[Naptown]

hi i have a 18 v 32.5 amp approx 583 watt system ,with 9 panels and 65 watts each. the distance to the 12 volt bank is about 13ft to the closest panel. Would 6 awg wire be good enough without too much power loss? also the wire coming from each panel is smaller (12 or 10 gauge ) is that a problem?

You will need a combiner with 9 spaces to combine your panels each panel will need to be fused. you will also need to calculate the voltage drop for the distance from the combiner to the charge controller

and what gauge wire for my battery bank? ,will probably be 2 230amp hour 6volt golf cart batts in series, will these charge too fast?possibly damage them.

Depends on what the inverter size is

and one more thing, I know this is a lot of questions at once and this i Is not the best question, but If I wanted to use 2 12 awg wires wraped nicely would this be sufficient (with insulation)
No you must use single conductors only

. Or should i just buy the 6 awg
Dont know if this is big enough yet but suspect you may need a #4
Whatever your final current output is from the panels say it is 50A the wire from the combiner to the charge controller will need to be rated at a minimum current carrying capacity of 156% of the projected current. meaning the wire will need to be rated at 78A minimum

Comments in red

[Sunking]

hi i have a 18 v 32.5 amp approx 583 watt system ,with 9 panels and 65 watts each. the distance to the 12 volt bank is about 13ft to the closest panel. Would 6 awg wire be good enough without too much power loss?

Using a #6 AWG with a load current of 35 amps, @ 18 volts, 15 feet will develop 2.8% voltage drop which is a little high but acceptable. I would suggest #4 AWG copper to get down to 2%.

also the wire coming from each panel is smaller (12 or 10 gauge ) is that a problem?

No it is not, it is after they are combined. As Rich pointed out you will need a fused 9 position minimum combiner with disconnect to combine all 9 panels. On the load side going to the controller is the #4 or #6 AWG feeder cable.

and what gauge wire for my battery bank? ,will probably be 2 230amp hour 6volt golf cart batts in series, will these charge too fast?possibly damage them.

OK you need to clarify what section of cable you are referring to. Is it the cable from the controller to the battery? Or is it from the battery to load devices like an inverter?

If from the controller to batteries it is sized based on the controller output current and distance to the battery terminals to keep loss below 1%. The minimum size required is selected from Table 310.16 in the NEC based on the Controller output fuse. This should be listed in the operators manual. For example if the controllers output over current protection device is 40 amps the minimum wire size is #8 AWG and that would work up to 3 feet one-way distance to maintain 1% voltage drop.

If it is from the batteries to inverter will depend on the fuse size and length feeding the inverter.

So until you can answer the questions I will not be specific.

and one more thing, I know this is a lot of questions at once and this i Is not the best question, but If I wanted to use 2 12 awg wires wrapped nicely would this be sufficient (with insulation) . Or should i just buy the 6 awg

No way CAP. It does not work that way, and second you are not allowed to parallel supply conductors unless special conditions are met. One of the conditions is the conductors must be 1/0 or larger.

FWIW #12 AWG is good for 20 amps, and #6 Awg is rated for 65 amps.

[Naptown]

Now if you give some specs on the charge controller we may be able to help you a bit wiring wise.

[Mike90250]

You could save some $ by using aluminun #2 ga (equal to #4 copper) and aluminun rated gear.

See the wire caculator in my sig

And you could re-configure and use a MPPT controller, save copper, and maybe save a couple panels, to offset the mppt co$t

[CAP]

Thanks

thanks for covering everything, glad to see helpful posts. I will take into account aluminum number 2,or copper 4/6 for wiring. about the battery banks I was curious if a larger wire connecting the 2 230 amp hour batteries are needed. other wise i was going to use the 4 or 6 wire, they will be in a series since they are 6 volts

[Mike90250]

thanks for covering everything, glad to see helpful posts. I will take into account aluminum number 2,or copper 4/6 for wiring. about the battery banks I was curious if a larger wire connecting the 2 230 amp hour batteries are needed. other wise i was going to use the 4 or 6 wire, they will be in a series since they are 6 volts

Your battery interconnect wire, will have to carry a LOT of amps, depending on what your load is. 500watts load on an inverter generally pulls about 600 w out of the battery, and @ 12V, that will be 50 amps. That can be a lot of loss.

[TomP]

Your question seems to be answered, I would just add that I see no reason not to use the largest cable you can afford, thus allowing for growth and added panels, as will always happen. I may be wrong but live by the big is better when it comes to wire, but then I was on 12 V, when there was no choice.

At one time I was using 600 MCM ( had to use a pipe bender to shape the stuff,) from the battery to a Trace 2412, I saw the well pump peg my fluke meter many times. For local AC wiring I believe in 10/2 and 12/2.

[CAP]

battery power loss

so right now I have two 6 volt batteries, in a series for 12volt total.each battery is 230 amphours. when I run a fan around 120 watts ,it will only stay on for about a hour.and then the inverter shuts off cause of low voltage. The voltage only goes to 11.7 when fully charged, (im assuming its fully charged). the voltage goes down to 11.3 as soon as I turn on the fan an decreases to 10.3 or so in about an hour before turning off. These batteries were sold to me as new but im not sure now. the system is probably putting out about 25 amp and 450 watts. what do you think the problem is ,do i need more batteries or do u think the current batt's are bad. or is it not battery related

[Sunking]

The voltage only goes to 11.7 when fully charged, (im assuming its fully charged). the voltage goes down to 11.3 as soon as I turn on the fan an decreases to 10.3 or so in about an hour before turning off.

Well let's put it this way: A fully charged battery that is rested with no load or charge should be about 12.6 to 12.8 volts. If fully discharged will measure 11.9 to 12 volts.

What does that tell you?

[Mike90250]

Well let's put it this way: A fully charged battery that is rested with no load or charge should be about 12.6 to 12.8 volts. If fully discharged will measure 11.9 to 12 volts.

What does that tell you?

The meter is broken ?

[TomP]

The meter is broken ?

He is full of sarcasm, myself, who spends many hours a day on camera forums, am accustomed to answering the same easy to find answers to newbies, over and over again, with respect and courtesy. He wants you to know the batteries are dead, you also need a good hydrometer to test your fluid.

[CAP]

ok ,sounds like the batts are bad then because they are getting enough power to be fully charged. so should the voltage of 2 6volts be the same as 12 v when fully charged.(12.6). also the inverter is reading the 11.7 - 10.3 volts ,i will test the batts directly and see if there is a voltage change,or maybe my inverter is bad the voltage o apply to two 6volt batts

Well let's put it this way: A fully charged battery that is rested with no load or charge should be about 12.6 to 12.8 volts. If fully discharged will measure 11.9 to 12 volts.

What does that tell you?

[russ]

He is full of sarcasm, myself, who spends many hours a day on camera forums, am accustomed to answering the same easy to find answers to newbies, over and over again, with respect and courtesy. He wants you to know the batteries are dead, you also need a good hydrometer to test your fluid.

Well goody, goody for you - you get a gold star!

[Sunking]

ok ,sounds like the batts are bad

They are well beyond dead. When fully charged up during th eday with the panel producing power you should be seeing around 14 volts. 11.9 volts at rest is completely discharged. 11.7 is toast.