Cable size

Ron-D · Guru

Cable size

PeterD · Guru

Don't stuff around. Get the new regulator NOW. If you delay the purchase you will need heavier cable to give a lower voltage drop for the existing regulator to be useful (which ip probably wont be, it will probably be a reg fixed at 13.8V.)

You did not say how long your "long lead" will be so we can not reliable advise the necessary size of cable.

Ron-D · Guru

Thanks for our reply Peter the cable length is five meters ,I will definitely buy a new regulator before. I use this panel ,my only problem was because of the tiny cable size in the panels themselves ,would that small diameter cable size at the actual panel itself support a five meter cable run to the regulator ,that will now be moved from the portable panel and be placed close to the battery.

Craig1 · Guru

My 130w new panel has 2.5mm sq wire with 1 metre leads, but the insulation makes it look twice as big as a twin core 2.5mm sq cable (supplied by my auto elec). the copper is the same once stripped however, prior to fitting a 3 metre extension via Anderson plugs to 2nd tug battery. No fitted regulator on this panel from Vic Off roads. cheers Craig. ( the 2.5mm sq description comes off cable drum label)

PeterD · Guru

If you use twin 6 mm auto cable you will get 0.35 V drop over the cable at the full 10 A your panels will deliver. If you use 6 mm2 cable the voltage drop will be 0.28 V. These voltages will not be significant if the controller is at the battery but will be with the controller at the panel.

macka17 · Guru

Put regulator at Battery end. No matter HOW long the cable run.

Then go to Lawrence\Hanson. or any electrical supplier.
(Any solar installer near you?.)

Buy the length of cable THEY use on house roofs. and solder\crimp, that in.
A lot thicker than you think you'll need. BUT
the right cable for that job.
Current loss. WHAT current loss. Do it properly.
I bought 7 mtrs for mine recently.
It's "stiff" cabling. Holds a bend.

macka17 · Guru

This cable (there is a thicker one too.)
Measured by Vernier not fancy Squared figures.

Outer double sheath.
11mm X 5.5mm.

Individual Copper cores. == 2.8mm Dia, on Vernier.

They use this on roof panel runs on houses.
Should be gud enuff for caravan hey.

Tony Bev · Guru

I am not an Electrician

On my Jayco Conquest (in my Avatar)
The solar panel wire from near the battery/s to the roof is pre installed

It is fairly light gauge wire, of approximately 5 metres in length
I was unable to replace it, as it is stuck somewhere within the cavity of the wall
I could only add to it

The total run of my wires from my 300 watt roof solar panel, to the regulator near the battery, is about 8 metres long
I was initially worried about the power drop, of the pre installed wire run

During my testing, on a good day after running down the batteries, I was seeing around 19 volts, and 13 amps, at the regulator

As others have said, having the regulator close to the battery/s, is the way to go

Aus-Kiwi · Guru

Then to confuse things ..The type of regular helps too !!

Ron-D · Guru

Looking at the mppt etracer controler $170 dollars 20amp model anyone any advice on a good controler model ....

thats interesting Tony from your experience it sounds like just crimping a well ,medium sized cable onto the puny little cables at the panel won't cause much of a voltage drop as long as the reg is near the battery.

-- Edited by Ron-D on Sunday 5th of November 2017 06:41:28 PM

macka17 · Guru

As long as first part of cable can carry full load from panel out.
Dia for distance travelled Loss..

I've used Morningstar for a long time now. Good. Reliable. very few hassles.
Heavy duty stuff. try the "Trace"

Cupie · Guru

Unfortunately my 200a panel is 9m from the battery.

I am using 6AWG to my DC/DC charger that has a MPPT solar reg.

Same size cable used from Alternator to Anderson plug on tug (via a relay off the Accessory wire). Yes old fashioned I know.

When I get the time I will replace the Jayco's 8AWG from its Anderson plug to the DC/DC with 6AWG cable.

Then I think that I will install a couple of Anderson plugs to allow me to change the alternator feed to the DC/DC charger, to feed the 12v fridge for traveling. Let the solar top up the battery if it has been only lightly used. We don't free camp very much.

BTW everything that I read advises me to use MPPT reg & place it as close to the battery as possible.

Also ... good deals on 6SWG cable (by length) can be got from 'Big Al' on eBay. Fast delivery.

6SWG is a good fit for 50a Anderson plugs too.

ps. I get confused with all these different wire gauges so I stick to American Wire Gauge AWG, which I now am familiar with. Fancy the Yanks having a useful standard.

-- Edited by Cupie on Monday 6th of November 2017 02:38:50 PM

macka17 · Guru

Hey Cupie.

I get confused too.
So I just strip a bit of sheath back. Roll core in fingers and Vernier the dia of that strand.
Normally around 2.8mm, Finger rolled Core dia. Do have some thicker.

Seems to hold voltages for any length I've used up to 40ft in Yachts.
Transom Panels frame, to Under Centre ****pit Battery banks..

Cupie · Guru

macka17 wrote:
Hey Cupie.

I get confused too.
So I just strip a bit of sheath back. Roll core in fingers and Vernier the dia of that strand.
Normally around 2.8mm, Finger rolled Core dia. Do have some thicker.

Seems to hold voltages for any length I've used up to 40ft in Yachts.
Transom Panels frame, to Under Centre ****pit Battery banks..

Sorry that I took so long to reply. I just dropped in to see if there was anything interesting newly posted.

After reading your post I slipped down to the workshop to check the dia of a bit of 6AWG ... It measures around 4.9mm depending how hard I twist it or squeeze the vernier. So a fair bit bigger than the stuff that you use. From the table, 6AWG of solid wire is 4.115mm!

From a reference that I pulled up ....

The AWG tables are for a single, solid, round conductor. The AWG of a stranded wire is determined by the cross-sectional area of the equivalent solid conductor. Because there are also small gaps between the strands, a stranded wire will always have a slightly larger overall diameter than a solid wire with the same AWG.

AWG is also commonly used to specify body piercing jewelry sizes (especially smaller sizes), even when the material is not metallic. (What size is your navel ring? LOL)

Here's some more useless information ...

Rules of thumb[edit]

The sixth power of ${\sqrt[{39}]{92}}$ is very close to 2,^[5] (the ratio between successive sizes to be the 39th root of 92, or approximately 1.1229322.)^[4)(I bet that you knew that..C LOL)which leads to the following rules of thumb:

When the cross-sectional area of a wire is doubled, the AWG will decrease by 3. (E.g. two No. 14 AWG wires have about the same cross-sectional area as a single No. 11 AWG wire.) This doubles the ampacity.
When the diameter of a wire is doubled, the AWG will decrease by 6. (E.g. No. 2 AWG is about twice the diameter of No. 8 AWG.) This quadruples the cross-sectional area and the ampacity.
A decrease of ten gauge numbers, for example from No. 12 to No. 2, multiplies the area and weight by approximately 10, and reduces the electrical resistance (and increases the conductance) by a factor of approximately 10.
For the same cross section, aluminum wire has a conductivity of approximately 61% of copper, so an aluminum wire has nearly the same resistance as a copper wire 2 AWG sizes smaller, which has 62.9% of the area.

With all this so simply explained it's a wonder that I get confused .. hey!