Charge Controller Switching Off

Jamesadele

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Jun 26, 2021
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Hi guys. I set up a new 100w panel to my new 20amps charge controller and connected a little 12v 7ah batterry inside it stays on fine and very slowly adds charge. I have now moved jt outside and the controller is now charging mych better but also turns off about every 30 secs for about 10 secs then just comes back on. I can hear a relay click in and out when it does this and the display goes off as does the out put to the onboard usb ports. I have no experience of these things so i dobt know if its faulty or somr sort of mismatch etc. Any help much appeciated. Its EPever controller if it makes a difference. Thanks for any help in advance.
 

Jamesadele

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Jun 26, 2021
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Update. Seems if i part shade the panel it drops the charge current and voltage of the panel and it stays on fine. Is the battery too small?
 

grizzzman

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Update. Seems if i part shade the panel it drops the charge current and voltage of the panel and it stays on fine. Is the battery too small?
Possible 5.5 amps from your panel into a 7AH battery?(unlikely that high) That charge rate for such a small battery is huge. Is this a 15-20 dollar charge controller? Take it off the SCC and give a voltage of the battery in 24 hours or so.
 

Jamesadele

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Jun 26, 2021
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Thanks for the reply. I dont know its that high but the controller says it is. The controller is a made by EP ever which i dont think arr amazing but i believe make some good products. Its not a cheap cheap one and is consistently 40 pound. I purposely didnt get the cheap cheap ones. Looking at it it maybe that tje panel is supplying to much power to a little battery and its shutting off thinking its fully charged. That said i would expect the usb to stay live and they dont. In the pic attached the controller stays on with the few cells shaded and the battery voltage according to the controller stays around 12.6v and riding slowly. If i unshade the panel the charge amps double and the reported battery voltage rises very quick to 14v. Its very quick after this it shuts off. I think its the batt voltage but i dont see why the usb turns off.
 

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Substrate

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Your battery is too small.

That 7ah battery I'm assuming is a little sealed agm. Those typically have a max charge acceptance rate of 0.25 to 0.3C. (Where C is the capacity rating).

So the max charge current should be no more than 2.1A (0.3C). Under perfect conditions, the 100 watt panel is capable of about 5.5A, so basically you need to double your battery capacity. You may even see this spec on the battery itself.

What may also be happening with too high of charge current, is that your battery immediately zooms up to the CV setpoint of the controller, and now walks in a charge very slowly, especially if it drops to float. Essentially you are just going too fast with that small of a battery.

A *temporary* fix until you get a larger battery - seeing as how you are using what appears to be a thin-film panel, is to cover up / shade half of it! Not recommended for normal use, but that is one of the features of a thin-film vs mono/poly panels. Temporary fix only! Upgrade:

Since a 14ah agm battery is not common, an easier find upgrade is the 18-22ah versions. You could also go LFP, but that's a different discussion.

Now your battery is more in line with an acceptable charge rate.

One other common mistake is putting your battery on the "load" terminals - make sure it is on the battery terminals of the controller. Just checking.
 

chrisski

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I find a 100 watt panel can output 6 amps max when charging a 12 volt battery. This is only in full sunshine and when the panel is pointed at and angled to the sun. On a cloudy day, the same panel will only put out 1 amp. If you have a multimeter, you could test the Short Circuit amperage of the panel in the shade. If the amperage is 1 amp or less, you may be able to hook it to the battery. The bad part about this, is as the sum moves, the panel goes in the sun, and then all of the sudden its getting too much again.

I think the best solution as mentioned is a bigger battery, but if you need this smaller battery, a 20 or 30 watt panel should work.
 

Jamesadele

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Jun 26, 2021
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Firstly I just want to say thank you all for the taking the time to help me here its really appreciated.

The battery is just what I had knocking about having got the panel cheap on prime day. However I did then get to thinking it would be a nice size to box up with the charge controller and take camping to charge phones and tablets etc. but I see thats not really going to work.

My major concern was that the controller is faulty and I wanted to get that sent back as I would have expected the controller to just stop charging not completely turn off but perhaps as said its a safety feature as it literally turns off completely, USB off, display off, charge off, load off, and you hear a relay click out when this happens then about 10secs later it clicks and it all comes back on.

The battery is connected to the correct terminals and I have metered the panel and it is around 5amp and 20 v in full sun and 1 to 2amps and 18v in cloud so panel appears to be good.

I am going to connect it to my car battery today when the sun is high and see what happens but I am certain now thanks to your replies that its going to be the battery that is too small for the panel.

As a side question. I appreciate my controller is not great quality so do they do reasonably priced controllers that are more programmable where I can set the max charge current and such like? From the limited manual I have for mine it appears I can set the battery type only and I have set it to Sealed.

Thanks again
 

mikefitz

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The controller should not be overloaded and turn off with the panel you have. It must be faulty, I suggest you return the unit for a refund.

The controller is a PWM type and the maximum current will be the same as the panel maximum, around 5 amps. If it cost £40, that's quite expensive for a small PWM controller.

The best controller for a small solar setup is Victron Smart 75/10, at £103 and as an alternative, the low cost Epever MPPT 1206N, at £47. Both will easily work with a 100 watt panel and will accept a second panel for a better overall daily yield.

Dont worry too much about charge current , to a large extent the battery itself determines what current it will accept ( lead acid battery). Of the two units in the link above, the Victron is fully programmable via the phone app. The Epever is also user programmable, but is less easy to implement compared to Victron.


Mike
 
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grizzzman

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Some controllers have an over voltage disconnect. If the software/hardware can not react fast enough, will disconnect then reconnect when it hits the voltage connect threshold.
 

chrisski

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I think his idea about using the car battery is a good one. I hope he tells us the results.
 

Substrate

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Actually that battery is TOO SMALL. Hook up to the car battery as a test to prove it.

The myth that you can charge small agm's really fast is not taking into account what happens on a SYSTEMS level:

1) With too much charge current, the battery very quickly rises to the CV setpoint TOO SOON.

2) The amount of charge it accepts with too much current is NOT EFFICIENT, but it surely drives the voltage up high really fast. (false promise when capacity is then measured)

3) The SCC immediately goes into a 2-hour timeout before it drops to float. This is not enough time in CV to fully charge *efficiently* further complicated by a premature drop to float and then the sun sets before things are done.

There is this myth that has been floating around for years like this. Unfortunately, the testers never took the trouble to do a capacity test and see that due to the total inefficiency, the regular C/20 capacity discharge test reveals how inefficient this is.

So the 0.25 - 0.3C maximum charge current on conventional agm's is there for a reason.
 

alaric michael

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Jul 15, 2021
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The problem here is your battery is too small.
That 7ah battery from my point of view is a little sealed agm. Those typically have a max charge acceptance rate of 0.25 to 0.3C. (Where C is said to be the capacity rating).

So the max charge current should be no more than 2.1A (0.3C). Under perfect conditions, the 100 watt panel is capable of about 5.5A, so in short you need to double your battery capacity. You may even see this spec on the battery itself.
 
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