Solar Panel Not Charging Well - Fiberglass RV


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Old 06-19-2017, 07:57 AM   #1
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Solar Panel Not Charging Well

I have a suitcase panel setup, two smallish panels for 95W total. Lately, they don't seem to charge as well. It used to be that as soon as the early morning sun hit them, my trailer monitor would be glowing brightly telling me the battery was charging.

Lately, it often is only in the "good" range, not "chrg", with full sun on the panels, and I seem to always be in the "fair" range by morning the next day.

I don't know if it's more likely a battery problem or panel problem.

So...my stuff:

Battery was new in March of 2016.
Water levels are good.
Panel is clean.
Terminals have some dust and dirt but no corrosion and are fairly clean.
I've never run the battery dangerously low, and kept it in an insulated garage over last winter.

The strange thing is, if I notice that it doesn't say "chrg" on my panel, I can go out and disconnect the solar plug, reconnect it, and my panel will then say "chrg". But the connections are clean and have dielectric grease on them (and not too much).

I just have the portable panels connected straight to the battery with the typically solar plug disconnect.

Any ideas?
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Old 06-19-2017, 08:28 AM   #2
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Maybe it's the charge controller on the panels.... Not sure how you check that.
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Old 06-19-2017, 09:07 AM   #3
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A test with a battery hydrometer will tell you if it has a weak cell, that could be part of your problem.
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Old 06-19-2017, 09:15 AM   #4
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I would start by trouble shooting with a small digital multimeter. You can get one for FREE at Harbor Freight with a coupon. It will read voltage and amperage, perfect for solar applications. Check your battery(ies) voltage first would be my starting point, if they are fully charged your charge controller should not say "charging", but maybe "trickle" or "float". Next I would check the voltage at the terminals coming into the charge controller to see what the panels are supplying. That will tell you if they are putting out their full rating. Then you can check the charge controller discharge to batter side to see what it is putting back into the batteries. These basic functions should allow you to isolate the problem. You can also use it to test continuity to see if you have a short or a faulty wire or connection. Beyond that may get to in depth for the scope of this thread and your level of knowledge to the individual components but should tell you if you have a bad battery, faulty panel or bad controller.
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Old 06-19-2017, 09:21 AM   #5
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If your panels are hooked directly up to your battery and not routed through a charge controller then I suspect this may have led to your problem. Any panel 30 watts and high requires a controller...
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Old 06-19-2017, 09:23 AM   #6
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Michael is correct, I didn't catch that in your post, you need a charge controller, especially to prevent over charging
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Old 06-19-2017, 09:40 AM   #7
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I read in the same sense as Michael, do you have a charge controller, between the solar panels and the battery?
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Old 06-19-2017, 10:51 AM   #8
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your panel.....

"my trailer monitor would be glowing brightly telling me the battery was charging"

if you are referring to the panel incorporated in your kitchen hood fan (along with tank monitors)....that will only give you very limited information...sort of useless once you start playing with/evaluating your solar system

here's a "real world" example that you might find interesting...

let's say that my system voltmeter is reading 12.35 (I have a four digit meter permanently wired in....I also have a second, three digit, meter wired in between panels and solar charge controller)

I have 70W of panel on the roof and a 40W portable/deployable...in bright sun the raw voltage from the panels (before plugging them into the system) is about 20 volts....once I plug them into the system through my separate solar charge controller the raw voltage meter (three digit) will drop quickly as the whole system equalizes....the raw voltage will stay slightly above the system voltage and climb over time as the system voltage climbs as well (battery is being topped up)...this continues untill system voltage reaches 13.33 (that is the value, unfortunately, where the controller stops charging the batteries by design)

after that the raw voltage will continue to climb and the difference between raw voltage and system voltage will become significant again (like when the two were not connected)

My AC battery charger will charge the battery right up to 14.45V for short periods of time....I have come to the realization that the only time my battery is 100% charged is after a long period plugged into shore power with charger on....the rest of the time my solar system probably only gets my batteries charged to 80% of capacity due to the 13.33 voltage limitation of my current solar charge controller (the "weak link" in my system is the cheap controller I have at the moment...meant to power a yardlight or gate system)

given my use, storage and solar charge capability this has not been a problem however as my system voltage (batteries) never seems to drop below 12.4V in every day use

I think you need to get yourself a good voltmeter and a hydrometer...it's a very good hobby to work with this stuff and figure out what is going to work for you and why...(solar is definitely not "plug and play")...have fun

(pic below shows the system in a state I described earlier....charge controller has stopped sending current to the batteries and the raw voltage (not being used) is significantly higher than the system voltage)
Attached Thumbnails
eproject5a.jpg   eproject2a.jpg  

spnew.jpg   solar.jpg  

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Old 06-19-2017, 10:59 AM   #9
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and a slight correction....

I wrote: "charge controller has stopped sending current to the batteries"....

in fact the charge controller is still sending some current to batteries....maintaining them at 13.3.....and not going above that...
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Old 06-19-2017, 10:26 PM   #10
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I'll read your post in depth tomorrow...too late tonight.

Thanks for the responses.

I have a multimeter and will use it.

I only talk about my trailers panel because in the past, it would always be glowing strongly and at "chrg" anytime the sun was full on my panels. Until just lately. So while it's not precise, it's predictable. And something is obviously off.

Yes the suitcase folding panel has everything needed for instant use, including a 3 stage charge controller.

After driving all day...my batter is worse than when I started. Down from "chrg" and "good" to "fair". Only thing that would have been running is my fridge fan. Issue might be my battery...

I'll get a hydrometer.
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Old 06-20-2017, 05:27 AM   #11
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Check the battery connections while you're in there.

I'd also check the voltage at the ends of the cables from the solar controller, do it with them disconnected from the trailer. Be careful, they are live.

cover panel
hook cable ends to the meter leads, meter on DC
uncover panel
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Old 06-20-2017, 07:36 AM   #12
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Not sure that I can test them unhooked. The charge controller doesn't turn on until it senses a battery to charge...
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Old 06-20-2017, 07:43 AM   #13
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Francois I wonder then...I practically never "plug in". So if my battery has possibly never been charged past 80% over the last year, with a lot of use...maybe I actually burned through it this fast. I don't know.

I'll check the water later this week. I know people get by with just solar and never plugging in, especially off-the-grid houses, so it must be possible. Who knows maybe one of those rare times I plugged in I fried my battery with my original, old power center in my camper, which I've been warned doesn't shut off when it should by others on this site. I never tested it with the voltmeter but I've always been sure to not leave it plugged in very long.

We'll see...
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Old 06-20-2017, 08:11 AM   #14
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Originally Posted by ZachO View Post
Not sure that I can test them unhooked. The charge controller doesn't turn on until it senses a battery to charge...
You can still check the Voc value at least, measured with no controller. It should approach the value on the spec sheet for the panel being measured, when in strong sun and fairly cool in temperature.

https://www.altestore.com/blog/2016/...y-solar-panel/

But with the limited information available, and not being on site nor knowing what equipment you have, I would still say that the battery is bad, or going bad, is my SWAG. If I could see it, some more common problems (such as corroded battery terminals) might be self-evident.
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