Solar panel extension wires

[Katdaddy]

We just bought a solar panel to help extend our batteries when dry camping. The wires provided with the panel are very short. I would appreciate recommendations for where to find extensions of 20 to 30 feet.

[MrWizard]

My Dico portable foldable array
The controller is separate from the array

[RambleOnNW]

ktmrfs wrote:

RambleOnNW wrote:

ktmrfs wrote:
another note: You want (well I say need) the controller to be near the battery, not on the panel. Especially if the cable is very long. A couple tenths of a volt drop in the cable really reduces charge rate.

But most every portable panel mounts a controller on the panel. Consider either removing the controller on the panel and mounting it near the battery, or bypassing it completely and using an onboard controller.

.2 volts drop with 10 amps would be a 2 watt loss in the extension wires which is insignificant. Also as the battery approaches full charge the current drops so the voltage drop steadily decreases.

I have the controller at the panel and it is set to AGM mode which produces a max voltage of 14.4V. Measured, it is producing 14.47V at the panel and 14.4V at the battery with a 40’ 8 AWG cable set and 5-6 amps.

the issue is not just the voltage drop. It's the acceptance rate of the battery as a function of applied voltage. It is not a linear function. a few tenths of a volt difference at the battery can results in many amps difference in what the battery will accept. On a small panel it may not make much of a difference. If you have enough current available on a discharged battery it can make a huge difference. As you get to full charge the difference becomes minimal, but it will affect the time it takes to get to full charge.

The trickle charge of solar is not that great for the AGM batteries I use anyway. Clouds passing through will significantly drop the charging voltage/current.

For that reason I am unconcerned about a small voltage drop.

When I am done dry camping I will plug in and hit the batteries with the 14.4V/45A of the Progressive Dynamics 4-stage converter/charger.

[ktmrfs]

RambleOnNW wrote:

ktmrfs wrote:
another note: You want (well I say need) the controller to be near the battery, not on the panel. Especially if the cable is very long. A couple tenths of a volt drop in the cable really reduces charge rate.

But most every portable panel mounts a controller on the panel. Consider either removing the controller on the panel and mounting it near the battery, or bypassing it completely and using an onboard controller.

.2 volts drop with 10 amps would be a 2 watt loss in the extension wires which is insignificant. Also as the battery approaches full charge the current drops so the voltage drop steadily decreases.

I have the controller at the panel and it is set to AGM mode which produces a max voltage of 14.4V. Measured, it is producing 14.47V at the panel and 14.4V at the battery with a 40’ 8 AWG cable set and 5-6 amps.

the issue is not just the voltage drop. It's the acceptance rate of the battery as a function of applied voltage. It is not a linear function. a few tenths of a volt difference at the battery can results in many amps difference in what the battery will accept. On a small panel it may not make much of a difference. If you have enough current available on a discharged battery it can make a huge difference. As you get to full charge the difference becomes minimal, but it will affect the time it takes to get to full charge.

[red31]

RambleOnNW wrote:


.2 volts drop with 10 amps would be a 2 watt loss in the extension wires which is insignificant. Also as the battery approaches full charge the current drops so the voltage drop steadily decreases.

I have the controller at the panel and it is set to AGM mode which produces a max voltage of 14.4V. Measured, it is producing 14.47V at the panel and 14.4V at the battery with a 40’ 8 AWG cable set and 5-6 amps.

most DVM are not fast enough to measure the ON/OFF of the CC in absorption. If ya switch a 5A load on and off 1/2 the time the current is still 5A when on and not 2.5A (current drop?). Less sun does = less current = less vd.

remote voltage and temp probe are available with some CCs

[RambleOnNW]

ktmrfs wrote:
another note: You want (well I say need) the controller to be near the battery, not on the panel. Especially if the cable is very long. A couple tenths of a volt drop in the cable really reduces charge rate.

But most every portable panel mounts a controller on the panel. Consider either removing the controller on the panel and mounting it near the battery, or bypassing it completely and using an onboard controller.

.2 volts drop with 10 amps would be a 2 watt loss in the extension wires which is insignificant. Also as the battery approaches full charge the current drops so the voltage drop steadily decreases.

I have the controller at the panel and it is set to AGM mode which produces a max voltage of 14.4V. Measured, it is producing 14.47V at the panel and 14.4V at the battery with a 40’ 8 AWG cable set and 5-6 amps.

[RickLight]

ktmrfs wrote:
another note: You want (well I say need) the controller to be near the battery, not on the panel. Especially if the cable is very long. A couple tenths of a volt drop in the cable really reduces charge rate.

But most every portable panel mounts a controller on the panel. Consider either removing the controller on the panel and mounting it near the battery, or bypassing it completely and using an onboard controller.

I did that and am glad I did. I also strung a steel cable along the power lines so I can lock my portable panel to the rig.

[ktmrfs]

another note: You want (well I say need) the controller to be near the battery, not on the panel. Especially if the cable is very long. A couple tenths of a volt drop in the cable really reduces charge rate.

But most every portable panel mounts a controller on the panel. Consider either removing the controller on the panel and mounting it near the battery, or bypassing it completely and using an onboard controller.

[bpounds]

Without getting into wire sizing, since no one here knows how your layout will run, I found lots of extension length options on Amazon. What I ended up doing was buying just 1@ 100' extension (cheapest per foot), and a bag of MC4 connectors. Then made all the extensions I needed in exactly the lengths I wanted. Soldered all the connector pins. I didn't bother using the M/F connector on the purchased cable. Trusted my own more.

[MrWizard]

Then you will have to cut and splice
To create your longer cord
You can use whichever cord and connectors
You want

[Katdaddy]

Thanks for the replies. This is a 130w suitcase kit. The wiring that comes with it has alligator clips at the battery end and no connectors for attaching to the charge controller.

[RambleOnNW]

I use WindyNation 40’ 8 AWG cables with MC4 connectors with a solar suitcase to keep the RV in the shade while the solar panels are in the sun. The cables come in a number of different lengths and wire gauges.

https://www.amazon.com/WindyNation-Extension-Connector-Variety-Available/dp/B01L6OU74M/ref=mp_s_a_1_...

[MrWizard]

My portable just has 2 prong combo male female bullet connectors, polarity observed, can not hookup wrong
Panel and extension cord, came from Amazon

[C_Schomer]

My 120 panels are 12 ga and the PO used 12ga extensions for a few feet to the j box on the roof and then 6ga down to the controller. I redid everything on the roof before I recoated it last year and I pulled on one of the the ext. connectors a little bit and out came the wire. I check all of them and another one came apart. The wires weren't pushed into the pins all the way before they were crimped. I cut out all the connectors and extensions and used 10ga thhn in hard pipe all the way to the j box and soldered everything. I won't have to worry about any of that again! Craig

[RickLight]

The chart above is good info, but going larger will cut the system losses.