Solar Kit

As current tapers during the 2 hr boost or 2 hr equal, the voltage drop tapers as it does on days with little sun or at the end of the day!

DAS26miles wrote:
BFL13- My clamp-on amp meter is fairly accurate. I have 2 other meters to check it. Plus I have a Xantrex Battery Monitor which gave the same voltage and amps that I read with the clamp-on. It's new and I do know that the cable from the controller to the batteries are 2x1.5mm which equates to 2 wires of 15awg. I ordered 10awg tray cable for my extension. Should be interesting to see if there is much of a drop. I could always change out the cables from 1.5mm (15awg) to the 10awg and see what happens.

Change it to 10 gauge, and get your panel as close to the battery as possible, and see what you get for voltage then, with a short cable run, as an experiment.

You better go over to See's Candy and buy her a 2 pound box of love while you're there.

You didn't mention what the parameters were that you programmed in.

Portable Solar panels are pretty much no brainer plug and play systems. Sometimes people run directly off the panel voltage during the day, and they don't need the extra voltage that charging a battery requires. To make it plug and play, it is optimized for the lowest common denominator so that is won't fry electronic circuitry. It's not set up or optimized for charging a battery.

You have to optimize it, tweek it, and modify it, to suit your special needs, if you want 100% or 98% battery state of charge. Otherwise, 14.4V factory settting and 90% state of charge will have to be "good enough" for the majority of buyers who don't care about such things. For some of us... 90% isn't good enough.

You're seeing voltage drop along, and due to, the wiring between the controller and the batteries.

That's the reason you see so much talk here in the forums of portable kits having their controller out at the panels instead of the controller being back at the batteries - where it really belongs for maximum energy transfer efficiency ... which is where folks put the controller in RV roof-top systems and RV portable systems they put together themselves. Since the kits are supposed to be ready-to-go plug-and-play systems, they have to come such that the user has nothing else to do to use them but set them up and attach the output cable to the RV's battery system.

The current you're seeing would be a bit higher if the batteries were seeing a higher voltage on their terminals and the batteries would be seeing a higher voltage on their terminals if the voltage was not being reduced by resistance in the wiring between the controller's output and the batteries. It's kind of a catch-22 vicious circle. However, the plug-and-play portable panel manufacturers and most users of them consider the situation as "good enough" ... as compared to the zero current they were getting from the sun's energy before they had any kind of solar at all!

BFL13- My clamp-on amp meter is fairly accurate. I have 2 other meters to check it. Plus I have a Xantrex Battery Monitor which gave the same voltage and amps that I read with the clamp-on. It's new and I do know that the cable from the controller to the batteries are 2x1.5mm which equates to 2 wires of 15awg. I ordered 10awg tray cable for my extension. Should be interesting to see if there is much of a drop. I could always change out the cables from 1.5mm (15awg) to the 10awg and see what happens.

"Why would the controller show 14.1 volts for the batteries and I get a reading of 13.4 volts when I check at the batteries?"

Assumes you have tried your meter against another meter or known voltage so it is not "reading low"

When there high resistance between controller and battery the controller thinks the battery is higher voltage than it really is. The controller starts "controlling" at a voltage set point of say 14.4v. So when it sees 14.4 it starts controlling and the battery can't get any higher in voltage---and it is really at some lower voltage than the 14.4 it was set to be at. So the battery will be "undercharged"

That is why all the fuss about getting the controller-battery path's resistance down. You can shorten the distance or fatten the wire or do both. Or the wire might be ok and it is a poor connection.

The DW surprised me today with the Renogy 100 watt suitcase solar kit with controller. She ordered it yesterday and I received it today. Valentine's Day, I feel guilty as I only have a card for her.
I set it up in my driveway and put in the perimeters and data into the controller. The controller immediately climbed to 5.2 amps at 14.2 volts at the panels and 14.1 volts and 5.2 amps for the batteries. Did a check with my clamp-on amp meter at the batteries and it showed 5.2 amps but only 13.4 volts. Why would the controller show 14.1 volts for the batteries and I get a reading of 13.4 volts when I check at the batteries? I suppose the important thing is the amps going into the batteries. Interesting to see the variations in amps and volts as it was a partly cloudy day.
Fits perfectly ,case and all, under the dinette seat. Only concern is the short 15 foot cable to the battery. I called Renogy and they don't make an extension yet for that model with the Anderson SB50 connectors. I found the connectors online at Battery Mart and the cable 10AWG 2 wire at Northern Arizona Wind and Sun.
64thunderbolt-wish I had the space for those 2 100 watt panels and the 30 amp controller, but this will do the trick for the near future.

This system is actually made for an outdoor lighting system. But I think it will suit my needs. I wish I had the knowledge but I don't. I have a basic understanding of it but am learning. I have issues with some of the abbreviated terminology but it is all good.

btw, I am running 2 6v gc2's

What is the Isc and Voc of your panels? I see the controller has Voc intake limit of 42v. That is normally not enough for two 12s which have about 22Voc each, so it is curious. (Relates to the same "issue" with the Eco-Worthy MPPT controller)

Specifications
Renogy 100W Polycrystalline Solar Panel
Maximum Power: 100W
Optimum Operating Voltage (Vmp): 17.8V
Optimum Operating Current (Imp): 5.62A
Renogy 30A PWM Charge Controller
Rated Charge Current: 30A
Max. Solar Input Voltage: 42V
Max. PV Input Power: 360W (12V), 720W (24V

(BTW it is really stupid to list the panel Vmp and Imp when it is a PWM set-up that could care less about the maximum power point! You want the Isc rating.)

On your results, they look good. You would see Isc of the moment, so the way to check your set- up is to get the Isc of the moment at the panel, then at controller display of amps. Should be the same.

If the batts are full and you have loads running, the amps to the battery will not be the same. Some amps will go to load first, then whatever is left over goes to battery.

What I like to see, is with the sun high and the panel aimed, to get rated Isc. Then with thirsty battery, to see battery accepting that many amps. However that just shows the panel can do its rating. All you need to see to know the set-up is good, is to compare the Isc of the moment (usually less than rating except at high noon, panel tilted South) with the amps at the controller to see they are the same, so no losses anywhere along the way.

OK, I turned on every light in the trailer, turned on 800w inv and a lamp with a 3 way bulb @ 150w. Left that for a few hrs with the panels covered. It didn't draw the batteries very much. I will post pics of my meter but the batteries weren't down enough. I will do the same after dark tonight. Here is what I saw today

Volts @ panels

Amps @ panels


Volts @ Bat


Amps @ Bat


This was about 3pm so not the best sun angle