We bought a DC Solar trailer for one of our remote sites. We got a second for backup purposes. My wife thought it was a waste to have the backup trailer just sitting on our property, so I tied it into our barn to run the pump etc. We added extra panels for that. Then since the remote site was 48V only, we removed the SMA inverters and installed them in our barn. We added 2 classic 250s and panels to run the rest of the house.
Several questions.
Do I need to give each pair of inverters their own batteries or can I keep them tied together. And do I need to setup the Classics in master slave mode? And what kind of cable do I use between them? What would the pin-out be?
TIA
I can't answer your question about the two inverters and batteries.
But if you have two or more Classics charging the same battery it is good to have them in Follow me since it coordinates the charging .
You just need six conductor telephone cable between them . I forget if 4 pin might work okay too. It has been awhile since I hooked mine up and don't remember .
You will find info on how to set Follow Me up at this link. Also I think there are some videos Midnite made in the past too.
https://www.midniteftp.com/support/kb/faq.php?cid=1
Larry
I had a 4 conductor phone cable. Plugged it in according to the FAQ. But did not see any blue blinking lights. Does that mean I need a 6 conductor?
I set the LED mode to comms test. The red light seems to be blinking fast. Any other way to test to see if it is working?
Quote from: keesh on June 25, 2025, 02:06:00 PMI had a 4 conductor phone cable. Plugged it in according to the FAQ. But did not see any blue blinking lights. Does that mean I need a 6 conductor?
Try a 6 conductor phone cord. I think that is what goes between MNGP and Classic , right ?
You just need a longer one. If you have a crimper you can always get the 6 pin ends and make one using cat5 cable ( just use 6 of the wires).
I think one of your Classics should blink blue soon as you put it in Follow Me mode - slow blue blink. The other one is faster blue blink. But it has been awhile since I set mine up and I forget.
Larry
So I got the master blue light long and the slaves blue light short.
I noticed that at this time, one of the slave is on absorb, while the master is on bulk MTTP Should not the slave follow the master? Also all three Classics 250 show different battery voltages. Is that normal?
All the battery temps are the same. (With only one battery sensor on the master, so I assume the master slave is working)
Now the master is floating, one of the slaves is floating but the in between slave is resting. Is that how it is supposed to be?
Quote from: keesh on June 29, 2025, 12:58:16 PMSo I got the master blue light long and the slaves blue light short.
I noticed that at this time, one of the slave is on absorb, while the master is on bulk MTTP Should not the slave follow the master? Also all three Classics 250 show different battery voltages. Is that normal?
All the battery temps are the same. (With only one battery sensor on the master, so I assume the master slave is working)
How are your Classic wired up . If they have different wiring to the battery they could have different voltage drops if not calibrated to read the same ( via tweaks). Each Classic could act differently depending on what voltages it is seeing . They should all go to Float when the master does though I believe.
Do you have the same firmware version on all your Classics ? Not sure if that would make a difference but doesn't hurt to be all the same.
In follow me all classics will not always charge. Absorb, Float and EQ are a regulated state and as the battery gets fuller and the current drops some classics will go to resting and the others will finish the charge.
Only when in a non regulated state, Bulk MPPT, Float MPPT, EQ MPPT and in direct sun will all controllers always be charging