Solar Kit

[64thunderbolt]

Just received my kit. 2 100w panels with a 30a pwm controller. Hoping it will recharge my 2 GC2's. I am alone in the trailer and power use is min. Any thoughts?

[NinerBikes]

Do a search here for "screwy 31" . It's a long read, but the Readers Digest condensed version is that when you are working with limited amp capacity from solar panels on stubborn to charge car battery shaped deep cycle batteries, you want to bump up the voltage slightly for charging purposes, to keep the charge controller in bulk mode longer, to effectively charge the battery the last few percentage points to get as close as possible to 100% state of charge before power production drops off with lower angle of sun, while still covering for amp losses as the CO detector, lights and refrig draw continue to suck amps off the top. A 5.5 Amp charge rate still has a draw coming off, making it effectively 4.5 to 4.75 amps per hour going into the battery if you have parasitic normal operation losses running 24.7 with the battery connected.

Bumping the voltage on a lead acid battery in a group 24, 27, 29, 31, or T-1275 battery, due to construction and engineering constraints, when solar charge rate is at c-10 or less, up to something in the range of 15.0V to 15.3 V, in essence, allows more amps to be pressed into the battery before the charge controller dumps back to float mode and 13.6V. It is a way to get the specific gravity back to where it truly belongs, moreso on a daily basis.

Check your specific gravity, that tells all about state of charge of a battery. Everything else is guess work. Specific gravity per cell never lies. 1.275 or better.

[DAS26miles]

Ninerbikes- what's the advantage of higher volts when the amps are maxed out either way? If I did change the cables, the ones from the panels are 1.5mm or 15 wag to the controller. The controller can only take up to 12awg wire. The 15' cable is also 1.5mm (15awg) from the controller to the battery hookup. The battery hookup is 12awg for the 2 feet. I did make up an extension of 2-10awg tray cable that's 18 feet long. Really stiff stuff.

[NinerBikes]

DAS26miles wrote:
Update on my solar suitcase kit. I found that the 2 panels 50 watts put out max 5.5 amps at the house batteries. Of course this is without any load from the motorhome to take away the amps charging the batteries. I purchased an additional 30 watt panel. It came with cable and separate section with alligator clamps. I cutoff the alligator clamps and attached the short cable to the panel input connectors at the controller. Now I can easily attach or detach the cable as needed for additional panel use.

I ran my house batteries down 15 amps on my Xantrex battery monitor. I Disconnected all power from the batteries and attached the 100 watt suitcase kit. I let it run for a few minutes and it got up to 5.5 amps at the batteries per my Xantrex battery monitor and my clamp-on amp meter. I then attached the 30 watt panel and the amps jumped up to 7.5 amps, also verified on the battery monitor and clamp-on meter. I let it run and came back to check on it. The voltage climbed to 14.6 volts on the controller for panels and batteries. I checked at the batteries and got the same amps, but the volts were 13.7 volts.
I let it run some more and the controller amps dropped down to 5.5 amps and the volts remained at 14.6. I disconnected the 30 watt panel, and the amps stayed the same 5.5 amps. Interesting, the second panel does nothing to add once the amps dropped down to the 100 watt suitcase max output. Also, the voltage did drop by .2 volts.

The new 30 watt panel along with the suitcase kit fit nicely under the dinette seat out of the way. I think I made a good choice.

Sounds like with just a little bit of fine tuning, you are now perfect for amount of amps you need. Next time, try it for 24 hours and 20 to 30 amps from full, with all 130 watts, and see how long it takes to drop down to only needing 5.5 amps.

You want that 14.6V at the battery terminals... fat wire and short run from charge controller to battery.... 3 feet or less, and 10 or 12 gauge wire, and call it good. Clean those battery terminals up to shiny metal and clamps up also to reduce resistance and voltage loss at the battery terminals also.

[DAS26miles]

Update on my solar suitcase kit. I found that the 2 panels 50 watts put out max 5.5 amps at the house batteries. Of course this is without any load from the motorhome to take away the amps charging the batteries. I purchased an additional 30 watt panel. It came with cable and separate section with alligator clamps. I cutoff the alligator clamps and attached the short cable to the panel input connectors at the controller. Now I can easily attach or detach the cable as needed for additional panel use.

I ran my house batteries down 15 amps on my Xantrex battery monitor. I Disconnected all power from the batteries and attached the 100 watt suitcase kit. I let it run for a few minutes and it got up to 5.5 amps at the batteries per my Xantrex battery monitor and my clamp-on amp meter. I then attached the 30 watt panel and the amps jumped up to 7.5 amps, also verified on the battery monitor and clamp-on meter. I let it run and came back to check on it. The voltage climbed to 14.6 volts on the controller for panels and batteries. I checked at the batteries and got the same amps, but the volts were 13.7 volts.
I let it run some more and the controller amps dropped down to 5.5 amps and the volts remained at 14.6. I disconnected the 30 watt panel, and the amps stayed the same 5.5 amps. Interesting, the second panel does nothing to add once the amps dropped down to the 100 watt suitcase max output. Also, the voltage did drop by .2 volts.

The new 30 watt panel along with the suitcase kit fit nicely under the dinette seat out of the way. I think I made a good choice.

[DAS26miles]

waynefi wrote:
I had removed a battery from the TT and set it on my porch while doing the experiment, so no other loads. I have set the timer to 180 minutes and the boost voltage to 15.

I did notice that the controller displays both panel and battery voltages, and I was looking at panel volts.That accounts for 0.1 of the difference, and now my DVM agrees with the controller measurement.

There is a fuse and an SB50 connector in the line, I'm not sure how much drop they contribute. The wire is marked as 1.5 mm2, so I think that is an area, not a diameter. I'm not sure what wire gauge that is.

I will probably re-wire with thicker wire.

I checked and the 1.5mm is the equivalent of 15awg. That's pretty small gauge wire. I researched it and the panels to the controller is fine for the 1.5mm, but recommended upgrading cable from controller to the batteries. My short little fused segment with alligator clips is 12awg.

Another question for you Solar Guru's out there. My Renogy suitcase 50 watt panels max at 18 volts and the 30 watt coming tomorrow has a max of 17.5volts. Does that prevent me from attaching them in parallel? What if I connect the 30 watt to a 50watt that connects to thew other 50watt and then to the controller? If not, I will just get another controller for the 30 watt. Any problem with a second controller hooking up to batteries at the same time?

[jrnymn7]

Wire Gauge Table

[waynefi]

DAS26miles wrote:
Waynefi-The cable used on the suitcase is 1.5mm or 15awg. I'm going to rewire mine from panels to controller with either 10 or 12awg. But the will use 10awg for the run to the batteries. If I move the controller to the MH, then I will use 10awg for that long segment.
Will look at the parameters tomorrow and see what I can change. That 120 minute timer on the boost should be changed, are you using 180 minutes?
Do you have anything running while the panels are charging? I found a drop of .6 volts which was from my fridge and parasitic stuff. Once I turned it off, the volts went up to -.1 volts below that of the controller.

I had removed a battery from the TT and set it on my porch while doing the experiment, so no other loads. I have set the timer to 180 minutes and the boost voltage to 15.

I did notice that the controller displays both panel and battery voltages, and I was looking at panel volts.That accounts for 0.1 of the difference, and now my DVM agrees with the controller measurement.

There is a fuse and an SB50 connector in the line, I'm not sure how much drop they contribute. The wire is marked as 1.5 mm2, so I think that is an area, not a diameter. I'm not sure what wire gauge that is.

I will probably re-wire with thicker wire.

[DAS26miles]

Waynefi-The cable used on the suitcase is 1.5mm or 15awg. I'm going to rewire mine from panels to controller with either 10 or 12awg. But the will use 10awg for the run to the batteries. If I move the controller to the MH, then I will use 10awg for that long segment.
Will look at the parameters tomorrow and see what I can change. That 120 minute timer on the boost should be changed, are you using 180 minutes?
Do you have anything running while the panels are charging? I found a drop of .6 volts which was from my fridge and parasitic stuff. Once I turned it off, the volts went up to -.1 volts below that of the controller.

[64thunderbolt]

SkiSmuggs wrote:

DAS26miles wrote:
What ever happened to the OP 64Thunderbolt. Sorry I ran off with his topic.

That is okay. He started a good topic and it grew and I'm sure he has learned like we all have. 🙂

I am here, just watching you guys. My 200w system is working fine so I am done. Even with an overcast day the batt are recharged by early afternoon. I have been running the heat & leaving lights on all night. The 2 GC2's are holding fine and the solar will produce almost 7a with cloud cover. Full sun over 10a @ 17+v as previous pics showed. The 7a is @ 14.2v then settles to 13.7v You guys are sharing a lot of good info so no worries. Isn't that what this forum is about? Good luck everyone.

cloud cover in Az is different than other places, lol

[NinerBikes]

DAS26miles wrote:
Ran a test today. Drained house batteries down 20 amps. Kept fridge running on propane. With fridge going and parasitic drain the draw is .6amps. Connected panels and end of day there was still 5.0 amps down. Panels went into float with .2amps charging at 13.2 volts.
I disconnected panels and started generator. When it settled in it was charging 5.0amps at 14.2 volts. Ran the generator for 20 minutes and the battery monitor showed 3.7 amps down.
So the panels are shutting down too soon before the batteries are fully topped off. The max voltage I saw on the controller was 14.4 volts.
Something I didn't consider was the basic draw of the fridge etc from the panels output. Thus max output of 5.8 gives me only 5.2 amps charging.
Tried to change charging perameters but didn't work. Hope Solar 30 controller will work better.

As stated previously, I set my solar 30 at 15.0v... that is actually about 15.3V measured with my DMM, output at the terminals of the solar 30 charge controller. You would be surprised how much longer it holds the amps at a higher level when the amp flow is so low at 5.5 Amps, compared to battery capacity, 150 A/H.

You will get a higher state of charge with your small set up of 130W of solar panels, on a daily basis, with the solar30 charge controller, and setting the bulk voltage higher.

[jrnymn7]

waynefi wrote:

jrnymn7 wrote:
wayne said,

"I'm seeing about a 0.6 volt difference between the battery and the controller with 3.5 amps flowing. That is a bit more than I expected."

That is excessive voltage drop for only 3.5a. For example, I see .09v (point zero nine) drop at 45a. It may be simply a disagreement in meter readings, between the controller's display and whatever you used to read voltage at the batteries? Confirm all readings with a single handheld meter, to be sure.

About 0.1v seems to be a mismatch between the meters. This seems to be about 16 gauge wire, which would be .004 ohms/foot. 3 amps over 30 feet at .004 ohms/foot should be 0.36 volts

There could be additional losses at the connections, and for sure if there's a circuit breaker or fuse in the circuit. Is that 30' one way, or round trip?

[waynefi]

jrnymn7 wrote:
wayne said,

"I'm seeing about a 0.6 volt difference between the battery and the controller with 3.5 amps flowing. That is a bit more than I expected."

That is excessive voltage drop for only 3.5a. For example, I see .09v (point zero nine) drop at 45a. It may be simply a disagreement in meter readings, between the controller's display and whatever you used to read voltage at the batteries? Confirm all readings with a single handheld meter, to be sure.

About 0.1v seems to be a mismatch between the meters. This seems to be about 16 gauge wire, which would be .004 ohms/foot. 3 amps over 30 feet at .004 ohms/foot should be 0.36 volts

[jrnymn7]

Regarding DAS's early float, is it not possible, just as BFL pointed out earlier, that voltage drop could be causing the controller to be "seeing" a higher Vbatt, and going into float prematurely?

Or it could simply be how the controller is programmed. Many chargers are factory preset to go into float too early, it seems.

Page 46 of 56 of the manual says float is at 13.8v default, and has an upper and lower limit. Does this mean the controller is adjustable? If so, DAS could set float at the upper limit of 14.2v to extend abs charging ( a little low, but way better than 13.2v).

Manual

[jrnymn7]

wayne said,

"I'm seeing about a 0.6 volt difference between the battery and the controller with 3.5 amps flowing. That is a bit more than I expected."

That is excessive voltage drop for only 3.5a. For example, I see .09v (point zero nine) drop at 45a. It may be simply a disagreement in meter readings, between the controller's display and whatever you used to read voltage at the batteries? Confirm all readings with a single handheld meter, to be sure.