Noob question #3- voltage shut off point?

[Dude77]

Hello folks,
Hoping you can help out a relatively new guy to the world of solar. I had another thread over here

Complete noob. Yep, another DC solar trailer question

No problem using hygrometer or adding distilled water while running. Just don't short any terminals. Besides metal blast, sparks around bubbling batteries would be really bad. Not that I expect much bubbling from such a small PV array.

diysolarforum.com

That most of my questions were answered. However a newer issue has sort of popped up. At what (LOW) voltage should a Sunny island converter shut off?

My original issue was that the inverter was kicking off when I was reaching about 47 volts. I have watered all the batteries very very recently and had one good day of running everything and I mean everything in my fifth wheel including my AC for the better part of 6 hours. Went to bed at about 10:00 p.m. with only my cell phone plugged in and the refrigerator running but by 6:00 a.m. I was cut off by the inverter. The midnight classic was saying my voltage was at 48 volts, the Sunny island was reading it at 48.5 volts.....

Today the issue arose when I fired up the AC units and had them running for all of about 2 hours when the master Sunny Island shut down. Immediately went out there and the midnight solar is reading the voltage is at 50.2 volts....

I can fully understand the inverter shutting off at some point going well below 48 volts, but why in the hell is it shutting off at 50 volts now?

Started running the AC at noon in broad sunlight hitting the DC solar trailer panels. Unit kicked off and shut down around 2:00 p.m. still in direct sunlight. What am I missing? Is there some parameter that I need to change on the Sunny island? Could the unit be getting too hot?

Thanks in advance!

 

[Dude77]

I have since fired up the generator, and here are my readings with the generator having run for approximately half an hour. Hopefully the pictures come through

 

[Samsonite801]

What is the Sunny Island low-voltage cutoff set to now?

 

[Dude77]

 

[Dude77]

What is the Sunny Island low-voltage cutoff set to now?

That I don't know, I'm not even sure where to find that

 

[Dude77]

Sorry for the crappy pictures, one looks like it says 5 hours, one of the screens in the upper left says full, one of the other screens though says at 18%..... All of this regarding the Sunny island pictures

 

[Samsonite801]

That I don't know, I'm not even sure where to find that

You might read in the manual on where the setting is. My first initial thought on it, is that the inverter is shutting down at the proper set voltage (whatever it had been set at), but since it was under high load from the AC units, when it got killed, the volts came upwards to a rest since no load on it anymore. Then the solar juice from the MC CC started bringing the voltage higher even more (by the time you read the current voltage)...

 

[Dude77]

You might read in the manual on where the setting is. My first initial thought on it, is that the inverter is shutting down at the proper set voltage (whatever it had been set at), but since it was under high load from the AC units, when it got killed, the volts came upwards to a rest since no load on it anymore. Then the solar juice from the MC CC started bringing the voltage higher even more...

Thank you. I guess my hunt begins for a complete manual of this beast. I had truly hoped this thing was plug and play ready and was not experiencing any issues whatsoever until just a couple weeks ago with my first post

 

[Dude77]

At what point though should I shut off my generator? Currently as I type this I'm at 54 volts. The most I've ever seen was 58. I don't want to overcook my battery

 

[Dude77]

At what point though should I shut off my generator? Currently as I type this I'm at 54 volts. The most I've ever seen was 58. I don't want to overcook my battery

Should I be going off of volts or should I be believing the Sunny island and its percent reading?

 

[Samsonite801]

Is it the 6048 ?

It won't cook the battery, the generator is just supplying the Sunny Island's charger circuit (via the AC input) which is aware of the battery type and it would eventually switch to float charge stage before it ever cooked anything...

 

[Samsonite801]

Manual for a 4548US and 6048US:

https://files.sma.de/downloads/SI4548-6048-US-BE-en-21W.pdf

 

[Samsonite801]

At what point though should I shut off my generator? Currently as I type this I'm at 54 volts. The most I've ever seen was 58. I don't want to overcook my battery

BTW, 58v divided by 4 would be 14.5v each if they were 12v batteries, so that is not an abnormal charging voltage for lead-acid batteries (which is about 2.42v per cell)...

 

[Dude77]

BTW, 58v divided by 4 would be 14.5v each if they were 12v batteries, so that is not an abnormal charging voltage for lead-acid batteries (which is about 2.42v per cell)...

Sorry, this is why I'm still calling myself a noob, I know better on other boards. I have a DC solar trailer with 10 panels at approximately 235 Watts each. Unit has two Sunny island converters and a midnight classic controller and combiner. Power is being stored to two forklift GNB wet cell forklift batteries at 48 volts

 

[Dude77]

Manual for a 4548US and 6048US:

https://files.sma.de/downloads/SI4548-6048-US-BE-en-21W.pdf

Thank you! And yes it is the 6048

 

[Dude77]

I am looking at page 168 of the PDF that you supplied, seems about the only thing readily apparent to me. Something that I am presuming to be battery temperatures. I have no way to check battery temperatures but the ambient outside temperature right now is about 100°. The nominal value mentioned in the PDF says 104° to 122° with an average value of 113°.....

Is there a setting or a screen on either the midnight classic controller or the Sunny island in which I can get a battery temperature read? 244 pages in that one manual alone, left alone with a noob to read, lol, yeah I'm in over my head!

 

[Samsonite801]

Thank you! And yes it is the 6048

Yeah, my friend has a solar trailer with a MC 250 and a set of 6048US's on it (and a Kubota generator) which I am fairly familiar with from working on his, so I figured yours must be one of these similar ones...

 

[Samsonite801]

I am looking at page 168 of the PDF that you supplied, seems about the only thing readily apparent to me. Something that I am presuming to be battery temperatures. I have no way to check battery temperatures but the ambient outside temperature right now is about 100°. The nominal value mentioned in the PDF says 104° to 122° with an average value of 113°.....

Is there a setting or a screen on either the midnight classic controller or the Sunny island in which I can get a battery temperature read? 244 pages in that one manual alone, left alone with a noob to read, lol, yeah I'm in over my head!

Usually when you charge on a lead profile, they may install a remote temperature lead on them to mount by the batteries so it can compensate the charge volts under different temps. Theoretically, the MC 250 might have one and the Sunny Islands should have one. If not with an external remote temp probe, it might be making adjustment to some extent with an internal probe. Not sure how to read temp on those. Maybe somewhere it the manual it will talk more about it.