Solar panel extension wires

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

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.

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.

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

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.

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.

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.

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.

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

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.