Panels producing too much voltage

[symbiosis]

Hi - I have noticed that in the summer my charge controller is regularly getting over 14 v from my panels which causes it to constantly disconnect (as it should due to the over-voltage protection working) and therefore not charging my battery. Is there a way that I can step down the voltage that they are producing to something usable?

[littleharbor]

Actually you want 14+ volts Charging your batteries. In a 12 volt system flooded lead acid batteries want up to 14.8 or even more to equalize while sealed lead acid want something in the 14.4 volt range. When your controller is done with the bulk and absorb phases it should float around 13.6 volts.

[symbiosis]

By the way, this is a PWM controller - would I still have this issue with a MPPT controller?

[sensij]

By the way, this is a PWM controller - would I still have this issue with a MPPT controller?

I don't understand what the problem is. As littleharbor wrote, voltage over 14 is indicating a good charge (or a high internal resistance battery, if you are hitting that voltage too soon, but that is a different problem). If your controller is only an on-off style, and not actually providing a float charge, them you would be better off upgrading to a 3 stage PWM. Mppt would be nice if you intend to grow the system.

[Sunking]

Hi - I have noticed that in the summer my charge controller is regularly getting over 14 v from my panels which causes it to constantly disconnect (as it should due to the over-voltage protection working) and therefore not charging my battery.

Sorry but you do not know what you are talking about. What you are seeing is normal. It takes at least 16 volts to charge a 12 volt battery. Most likely your battery is fully charged, and yes the voltage will go up to your panel Voc voltage. If you have battery panels, that will be up around 21 to 22 volts. Perfectly normal, and exactly what you want to see. Last thing you want to se at the end of the day before dark is a panel voltage less than 20 volts. If you see something like 13 to 15 volts means your battery is not fully charged up. At the end of the day you want to see 20+ volts regardless of controller type using a battery panel.

MPPT wil be even higher voltage. You can use 600 volt panels to charge a 12 volt battery. Assuming you have a 12 volt battery panel the voltage on a MPPT controller, panel voltage input will be between Vmp (17 volts) at full power, and goes up to VOC (21 to 22 volts) as charging stops.

PWM input voltage will be roughly the same as the battery voltage at full charge, (battery voltage + 1 volt), and as the battery approaches full charge the panel voltage will go up to Voc or 22 volts.

It is the Nature of the Beast.

[SunEagle]

It is possible the the OP has a cheap charge controller that will shut down if the input voltage gets above 14volts although most CC's should easily handle the Voc of a battery panel which would be ~22 votls max..

[Sunking]

It is possible the the OP has a cheap charge controller that will shut down if the input voltage gets above 14volts although most CC's should easily handle the Voc of a battery panel which would be ~22 votls max..

Then it cannot charge a 12 volt battery as you need 14.4 to 14.6 at the battery. If that is the case, he would be better of with a Diode and throw that POS controller away.

[symbiosis]

Thanks for the replies all and yes I'm a noob with solar so am not as knowledgeable as I would like so please bear with me.

I made a quick video of what happens here https://youtu.be/0641OPUCAgQ as you can see, the voltage drops to 13.4 v and the panels are connected, it then jumps straight up to 14.2 v and disconnects. It continually does this in a loop. At night, my controller tells me my battery is around 12.8 v

[sensij]

That is what cheap controllers do, by design. Again, get a 3 stage controller with a float function for better results.

[symbiosis]

Thanks - That's what I thought was going on. Any recommendations for a 3 stage controller please?

[SunEagle]

Thanks for the replies all and yes I'm a noob with solar so am not as knowledgeable as I would like so please bear with me.

I made a quick video of what happens here https://youtu.be/0641OPUCAgQ as you can see, the voltage drops to 13.4 v and the panels are connected, it then jumps straight up to 14.2 v and disconnects. It continually does this in a loop. At night, my controller tells me my battery is around 12.8 v

I have a question. What is connected to the Load Terminals on that CC?

If that load is too big it could cause your CC to shut down.

[symbiosis]

Just a car radio, and its hardly ever on

[Wy_White_Wolf]

Sounds like the charge controller is shutting down just like it should when the battery is fully charged.

WWW

[SunEagle]

Just a car radio, and its hardly ever on

OK. I just wanted to eliminate any potential load that might be causing the CC to stop working.

I (along with others) feel the CC is not working properly. It should stay on and continue to charge a 12volt battery at 14+volts if the panel is continuously providing the nameplate Vmp.

[sensij]

OK. I just wanted to eliminate any potential load that might be causing the CC to stop working.

I (along with others) feel the CC is not working properly. It should stay on and continue to charge a 12volt battery at 14+volts if the panel is continuously providing the nameplate Vmp.

No, I think the charge controller is working just as it is designed. On-Off style style controllers do not stay on and continue to charge, they do not provide a float voltage. As the battery degrades, the on-off cycling becomes more pronounced. The current delivered during the on portion is enough to spike the voltage above the cut-off due to the batteries internal resistance, but after the charge current is removed, the battery quickly rests back to below the trigger voltage, turning the controller back on. This cycle continues for as long as decent charge current is available.

If this is the only controller those batteries have ever seen, they are probably in rough shape, having never been given a real absorb or float voltage (let alone EQ, if FLA). A better controller will help, but new batteries are probably in the OP's future.

An inexpensive controller that would be an upgrade to what the OP has now:

https://www.amazon.com/ALLPOWERS-Con.../dp/B01MU0WMGT

Mppt is worth considering if the system will ever grow, but is not always worth the money for small (<250 W) systems.