Does anyone run a solar panel with a digital controller?

[brian_bp]

That really doesn't look like a 65 watt panel. It looks small like a 10 or 12 watt.

I thought that it looked small at first, then I realized from the door that this is presumably a big teardrop... the scale is not obvious.

Here's more of the specs:

Dimensions (LWD): 29.6" x 25.7" x 2.1" (751 x 652 x 54 mm)
Weight: 13.2 lbs (6.0 kg)

That's a big thing... 65W may not be so surprising.

[mikeschn]

I know scale can be a funny thing...

This might help!



Mike...

P.S. Does your controller do the 0.3 to 1.5 and back to 0.3 amp thingie that I asked in my last message?

[brian_bp]

... Does your controller do the 0.3 to 1.5 and back to 0.3 amp thingie that I asked in my last message?

Mine is too dumb to do that - it's the simple type that has no way to regulate current other than just on/off... and it doesn't flip rapidly between the two.

The only other comment from someone who mentioned having a digital controller is emiller, with the Mark 15 controller; while it has a nice digital display, it is fundamentally the same thing as my simple switcher... but maybe switching a lot (the linked spec sheet suggests that it switches on and off frequently, presumably because the two set voltages are only 1.4 V apart). The SunForce unit should be much smoother, ramping down the current as the battery charges up, not jumping up and down as it seems to be now.

[DDkwac]

Hi
just a lurker but I use a Blue Sky 2512x mppt controller that has a 3-stage pwm charger.
It works nothing like yours is doing unless the battery is sufficiently undercharged

So, if your battery truly is reading 12v (measure it at the battery to see what the voltage is while disconnected from the charging setup.) you might first have to charge the battery up using a manual charger until it gets up to about the 50% mark or higher(12.06v) as most automatic chargers will fail to start charging unless the battery has sufficient charge to begin with.
This function is to protect against frozen batteries etc.

take care.

[brian_bp]

The concern about starting with a battery voltage which is too low makes sense, but according to the manual...

There is no minimum battery voltage for charging mentioned, although there is a "Solar power Weak" charging status.

The "low" level for battery voltage status is less than 11.5 (+/- 0.4) V, so 12V appears to be within the normal operating range.

If there is a low voltage condition causing a problem, it should be indicated by the "charging" and "charge complete" lights... which is why it would be helpful to know what they are doing, and thus what the controller thinks is going on.

The behaviour of common "smart" chargers - with a minimum starting voltage to charge - is probably better suited to automotive starting batteries (which should never be deeply discharged) than to deep-cycle batteries used in RVs and solar power systems. If the solar-powered RV setup stopped working when the batteries were only 50% discharged, it could be really annoying.


The Blue Sky Solar Boost 2512iX looks like a nice bit of equipment.

[Alphacarina]

Electrical Specifications
Model: KC65T
Maximum Power: 65 watts
Tolerance: +10% / -5%
Maximum Power Voltage: 17.4 volts
Maximum Power Current: 3.75 amps
Open Circuit Voltage: 21.7 volts
Short-Circuit Current: 3.99 amps

So maybe 1.5 amps is right for the autumn sunlight?

There's your 'clue' - 5.4 amps isn't possible, period. You're never going to see even 3.75 amps from this under absolutely perfect conditions because the 65 watts is computed at 17.4 volts and your regulator won't allow the voltage to go that high. It's a 'numbers game' Mike - They're using some unrealistic conditions to come up with the 65 watt rating. I've never heard of any 25 by 30 inch panel which can put out anything close to 50 real watts, let alone 65

I had a pair of 60 watt panels (physically much larger than yours) on my sailboat for a couple years, later replaced by a pair of 100 watters and I could get very near the rated output . . . . on a cloudless day in July at 25 to 30 degrees north latitude . . . . you're over 40 degrees north and that has lots to do with it, even in the dead of summer. I wasn't using any regulator so I'm sure that factors into it a bit. I had 2 banks of 400 AH batteries plus a 12 volt refrigeration system running off them 24/7 so I never came close to overcharging the batteries using no regulator. I have a single 15 watt panel on my Little Guy charging a single 75 AH Optima, again with no regulator. To get anywhere near the maximum output using your regulator, you're going to need a fairly large, pretty deeply discharged battery hooked to the panel, so your regulator will be at 'full on' - Any other set of circumstances will have your regulator limiting what's happening

To get the rated output, you'd need to be much nearer the equator, as previously mentioned because the sun has less energy the more atmosphere you subject it to and in Michigan, you never get the sun directly overhead, so you're at a disadvantage to begin with.

Don

[DDkwac]

If the solar-powered RV setup stopped working when the batteries were only 50% discharged, it could be really annoying.


The Blue Sky Solar Boost 2512iX looks like a nice bit of equipment.

Yes. it is annoying.
It only happened to me once this summer when I failed to realize most my panels had corroded connectors. The system had been performing flawlessly for over a year and I got lazy...
After I'd repaired the connections one of my banks wouldn't charge up. The bank measured 11.9v unloaded. I 'guessed' that the problem was the internal settings of my controller and I was forced by the situation to purchase a manual/automatic battery charger to bring the bank back up a bit. (charger cost half as much as new batteries)

Problem fixed.

In the op's case doing some checking should tell the whole story.
An unloaded panel in bright sun should have a voltage reading between 15v to 22v.
My mppt charger will read differently than other types, but all the other types I became familiar with will apply the panels total output current to the battery when the battery is discharged below 80%.
After the battery reaches an 80% charge condition, the pwm should start.
At 100% charge the controller should change to 'flout' mode i.e the rate of pwm changes.

(I should note that with the heavily discharged battery bank my controller just wouldn't turn on according to it's panel lights yet it would continuously check the condition of the battery every 1/4 of a second or so. Similar to how it operates in it's float mode. Similar to the op's controller.)

Op's controller appears to be not functioning right.
But-
I would carefully check my wiring before I did anything else esp. if I were on my second controller because I acknowledge I'm human, therefor capable of making human errors.

I would also check the solar panel(s) by applying it's output to a known good battery or other current sink. The op's output current should at least 1-3 amps on a sunny day. The measured voltage across the battery should steadily rise, indicating the battery is accepting a charge.

I would also check the battery.
It's also possible that a 12v battery with a bad cell will still read 12v (but not much greater then 12v) when the good cells are completely charged A load check on the battery is worthwhile doing.
The place you purchased your battery from or any auto parts store will freely do this check, because they expect to sell you a new one. You needn't feel obligated to do so.

After those other suspects are cleared of fault only then would I suspect the controller of being faulty.
(I will inject, if I received two faulty controllers from the same supplier I would consider changing brands of controllers and possibly changing my supplier.
Knowing me I would change suppliers first, if I was confident in my chosen device.
But thats just me.)

btw my first Bluesky failed due to my error yet the company replaced it under warranty.

More so my first controller (unnamed but not Bluesky) failed because the manufacturer overstated it's current handling characteristics.

I'm able to manually tilt my panels exactly towards the sun if I care to do so...
On a cool, bright sunny day in July my panels were outputting about 25% more power then they were rated for.
The charge controller I'd purchased was rated to handle 50% more than my panels rating, yet it failed.
Looking at the controller's insides the actual device for passing the panel's current could never handle as much power as the controller's specs indicated.

Bad choice on my part. I certainly couldn't use the replacement as the same conditions might happen.

[brian_bp]

Electrical Specifications
Model: KC65T
Maximum Power: 65 watts
Tolerance: +10% / -5%
Maximum Power Voltage: 17.4 volts
Maximum Power Current: 3.75 amps
Open Circuit Voltage: 21.7 volts
Short-Circuit Current: 3.99 amps

So maybe 1.5 amps is right for the autumn sunlight?

There's your 'clue' - 5.4 amps isn't possible, period.....

I agree that the original 5.4 amp calculated value was based on the erroneous (but reasonable) assumption that the power rating applies at 12V, but unfortunately it doesn't. The maximum current even under ideal conditions, without a real load (such as a battery) is that published 3.99 A value.

You're never going to see even 3.75 amps from this under absolutely perfect conditions because the 65 watts is computed at 17.4 volts and your regulator won't allow the voltage to go that high....

Well, not really. The current - again under ideal solar conditions - doesn't change much with voltage from zero volts (3.99 A) to 17.4 V (3.75 A), so you can get a bit more than 3.75 A... under ideal sun. For instance, at 12V the ideal current might be 3.8 A, but that would be only 46 watts. What you can't get at anything less than 17.4 V is the full 65 watts.

The regulator won't let 17.4 volts through, but it will allow as much current through as the panel can produce, during the "bulk charge" stage.

[brian_bp]

...An unloaded panel in bright sun should have a voltage reading between 15v to 22v.

Assuming that's with nothing connected, this is the "open circuit" voltage. As the spec says, it would be 21.7 V under ideal sun, and lower in less bright conditions.

...My mppt charger will read differently than other types, but all the other types I became familiar with will apply the panels total output current to the battery when the battery is discharged below 80%.

This is the "bulk charging" stage, in SunForce's terms.

...After the battery reaches an 80% charge condition, the pwm should start.

This is the next stage, described as "constant voltage" and "PWM" by SunForce (the controller is "throttling" the panel's output to control voltage).

...At 100% charge the controller should change to 'flout' mode i.e the rate of pwm changes...

This is the "float" stage.

The three stages are common for essentially all modern "smart" chargers and solar charge controllers.

Mike's controller seems to be confused about what stage it should be in, although I agree that the panel and battery checks are appropriate.

[brian_bp]

If the solar-powered RV setup stopped working when the batteries were only 50% discharged, it could be really annoying.


The Blue Sky Solar Boost 2512iX looks like a nice bit of equipment.

Yes. it is annoying.
It only happened to me once this summer when I failed to realize most my panels had corroded connectors. The system had been performing flawlessly for over a year and I got lazy...
After I'd repaired the connections one of my banks wouldn't charge up. The bank measured 11.9v unloaded. I 'guessed' that the problem was the internal settings of my controller and I was forced by the situation to purchase a manual/automatic battery charger to bring the bank back up a bit. (charger cost half as much as new batteries)...

If the panel is not so large that it would push an excessive current through the battery, it seems to me that the alternative workaround would be to just jumper the panel output directly to the battery for some manually controlled bulk charging time.

[mikeschn]

I'll go out tomorrow, provided the sun is shining, and take a video of the controller in action.

Maybe we can make some more sense out of it?

Mike...

[Alphacarina]

I think they've got it pretty well sorted out Mike

If you were at the equator (or wherever you needed to be depending on the time of year to have the sun directly overhead) on a cloudless day with your panel hooked to a 12 volt battery with no regulator, you're gonna get about 50 watts

In Michigan, in the summer on a cloudless day . . . . maybe 40 to 45 watts or so - Any less ideal conditions will give you something less. Here in the fall, your 'ideal max' might only be 25 or 30 watts on a really good day. If you were using the trailer and had a load hooked to the battery (electric refrigerator?) you could safely use that panel with no regulator at all and be pretty safe. Remember that with the regulator, you'll need a discharged battery to see what the panel can put out . . . . if the battery is nearly at full charge, the regulator is going to ensure that you don't make many amps

Don

[traildemon]

Did you ever get your charger panel sorted out mike?

Alphacarina: how does your small 15W panel and battery system work for you? Can you use it on its' own like this for an extended time? and what kind of appliances, and stuff are you running in your Little Guy?
ive been thinkin of getting a small 12v fridge, but i want to have electrical power for extended periods, so i am hesitant to buy one. Ill probably go with a cooler instead.

yea yea. i know... too many questions.. pardon me... im a newb.. LOL!

peace
al

[mikeschn]

No I didn't, not yet.

I didn't take a battery on vacation with me. And of course, here in Michigan in the winter, the sun is not especially conducive to charging.

But I'll get back to that in the spring...

Mike...

[mikeschn]

Now that the weather has improved, and the sun is a bit stronger, I've hooked up the battery again, and I am reviewing my solar controller.

It's a 65 Watt solar panel...

And the solar controller bounces back and forth between .4 amps and .5 amps.

That sounds a bit low for a 65 Watt panel. What do you guys think?

Mike...