Hoping the board is still somewhat active - I've owned a 3024 for awhile now and finally set it up. Everything seems to be running well but I have a question regarding the PV input. All seemed well and then at 2pm, the solar input literally fell off a cliff. It's a beautiful, sunny day but the input has been mediocre as you can see below.
Any ideas?
It could be that your batteries are full . If you don't have many loads and the batteries are full , you won't see much current coming in.
You didn't say what kind of batteries you have. Lithium will do exactly what you are seeing when they are full. Lots of current coming in and then it drops down quickly .
What kind of batteries do you have ? 67 volts is pretty high . What are your charging setpoints ?
Larry
Quote from: ClassicCrazy on April 13, 2025, 05:47:22 PMIt could be that your batteries are full . If you don't have many loads and the batteries are full , you won't see much current coming in.
You didn't say what kind of batteries you have. Lithium will do exactly what you are seeing when they are full. Lots of current coming in and then it drops down quickly .
What kind of batteries do you have ? 67 volts is pretty high . What are your charging setpoints ?
Larry
I wonder if you are right. I have three PowerQueen 24v 100ah batteries in parallel through a Victron PowerIn. Why it took me by surprise is that the MN3024 app has me at 83% SOC.
But looking at the setting more closely, I think you are right. I have it set to "boost charge" (absorb) at 28.8v based on the PQ manual. I am at 28.4v currently which I am guessing is the 83% SOC?
There are two settings on the MN3024 that I think may be in play? One is Parameter 10 which sets a "Battery Boost Charge Time." The default is to charge for 2 hours at that rate - I wonder if that could have shut it down?
The second is did the battery bank actually hit 28.8v and I didn't notice or the SOC didn't update to 100% (not sure how it calculates the SOC). That it shut down as you noted for being full.
That voltage I think is just what the PV array is delivering to the MPPT in the unit, not what the MN3024 is delivering to the batteries (that would be scary!!). I don't have a ton of loads as I wanted to start smaller and see what it could maintain in a critical loads panel.
It's an interesting learning process for sure - I appreciate your response and insight.
I don't have that controller so not sure about all it's settings.
I can tell you that for most lifepo4 batteries the voltage of 3.45v per cell is 99% full and most batteries these days will charge to 3.5v per cell to reset the bms reported soc to 100% .
I didn't look up your batteries but if they were mine I would be charging to 28v and an Absorb time or whatever they call it at between 5 and 15 minutes.
Some of these things are dependent on what the particular battery bms has programmed in for resetting it's bms to 100% ( which is only an estimate and doesnt have anything to do with charging ) . There is a balancing threshold in the bms as to where it will begin balancing. If you don't have a bms you can monitor each cell and possibly balancing, then it doesn't really matter much because you won't ever really know what voltages are on each cell. Since most power is in the middle flat part of the discharge voltage curve, it doesn't matter too much if they are out of balance at the very top ( and bottom ) unless you needed to get every last amp out of them .
And yes if the batteries were charging at absorb voltage setting you had that long and any of the cells went over 3.65v the bms probably shut them down .
Larry