Solar Panel Not Charging Well

[ZachO]

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?

[likeair2me]

Maybe it's the charge controller on the panels.... Not sure how you check that.

[larryf]

A test with a battery hydrometer will tell you if it has a weak cell, that could be part of your problem.

[Johnny M]

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.

[ckayaker]

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...

[Johnny M]

Michael is correct, I didn't catch that in your post, you need a charge controller, especially to prevent over charging

[Gilles]

I read in the same sense as Michael, do you have a charge controller, between the solar panels and the battery?

[Franswa]

"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)

[Franswa]

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...

[ZachO]

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.

[padlin00]

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

[ZachO]

Not sure that I can test them unhooked. The charge controller doesn't turn on until it senses a battery to charge...

[ZachO]

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...

[gordon2]

Originally Posted by ZachO

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.

[Franswa]

it's not precise, it's predictable.

LOL...pretty well sums up the whole 12V/solar "game"....I think you're on the right track....I agree with Gord...at this point the battery is suspect and should be investigated/cleared first....and go on from there

this sort of reminds me of cars and their electrical systems....alternator, voltage regulator and battery.....how many of us have replaced a perfectly good battery when trying to fix a problem with that system??? I know I have!!!!

I don't think charging a battery to 80% repeatedely will harm the battery to the point it will not perform....but OVERCHARGING and boiling it dry will. Problems with our old power centers and their chargers will and have done that often if one is to beleive all the posts on this and other sites....

Adding solar does add one more "fly in the ointment" making diagnosing an electrical system a little harder....but when it's working....it's like magic and well worth the effort....and yes, given our relatively limited power usage it's entirely feasible at this point to go 100% solar IMO (given a good solar charge controller....which I still lack)

have fun...

[stevebaz]

Measure the battery voltage at the battery clamp with the solar on. Measure the voltage at the battery post with the solar on. The post and clamp voltage should be the same if not clean your clamp and post.

Then disconnect your battery cables and check you actual battery voltage without any charge or loads on it. Then check the battery again 2 hours later still with no charge and battery cables un-attached. The voltage should drop some as the float charge dissipates.

Now check the voltage again 24 hours later still unattached. The battery should still have very close to the same voltage as you had after the 2 hour test. If its still dropping voltage after 24 hours the battery is having problems. Standing voltage on a standard good charged lead acid battery should be 12.7 volts. Once a battery wont hold a charge at over 12.4 volts its getting ready to give you problems.

At least that is my experience without going into all the math, science and theory and itty bitty details that get debated over and over again.

This is assuming you did your part and kept the battery full of distilled water.

[ZachO]

Thanks everyone.

I'll do some testing.

Zero corrosion at the battery terminals. They are dusty but definitely plenty clean. I checked the water levels yesterday and they were fine.

I sure hope I can expect more than one year out of a battery!

[ZachO]

Panel is putting out 13.97 V in the full morning sun.

Haven't checked anything else yet. I can really test my battery at rest because the fan for the fridge vent is running 24/7. If I decide I have to start living out of a cooler, I'll be able to shut that off and test the battery.

Still need to buy a hydrometer.

[gordon2]

Originally Posted by ZachO

Panel is putting out 13.97 V in the full morning sun.
..

Thats tells me... nothing. At least nothing until we know your Voc value.

You described your panels as " two smallish panels for 95W total" so I cannot even guess at the specs for them.

As an example, my 100 (or 50) watt panels have a Voc of 22.5 volts. If I was only getting 13 or 14 volts in bright sun, thats a problem. I wont get that high a voltage, esp. with an older (aged) panel, but it would be higher than ~14 volts.

Can you list the specifications, or at least make and model. of the panels?

And you did read the panel voltage with nothing attached. right? I ask again because ~14 volts sounds more like a charge controller output value.

[ZachO]

Yes sorry that's what it's charging my battery at, at the terminals.

I'll look at the panels later. I got them from a place that went out of business, called Off the Grid Solar. It's actually a "90 watt economy series". That's all my receipt says. Two 45w panels that fold and fit in a metal case. 3 stage charge controller.

I know I'm no expert but I did take some solar design and installation courses. Some of it is fading but I get the concepts. It seems like if it's putting out almost 14v at the battery terminals, then the panel is doing what it should.