I Flipped the Switch on my Over Paneled MN Classic & Array Upgrade Today

[Tecnodave]

@Hedges

Read up on “Follow me mode” for a real clue as to what several Classic’s in “follow me mode“ with only one Wb jr. connected to the lead Classic.

It does much more than what you describe


Disclosure: , I allready had Midnight Classic’s in service when the Midnight Wb jr. was introduced

 

[Hedges]

Read up on “Follow me mode” for a real clue as to what several Classic’s in “follow me mode“ with only one Wb jr. connected to the lead Classic.

It does much more than what you describe

In WBjr and Classic manuals, I find mention of each other. WBjr mentions "Follow me" and classic has many instances of "Follow-me"

From the documentation, I can't tell that Classic uses WBjr's measurements to set battery current. For all I knew it just reported the data for something else to monitor.

Classic mentions temperature compensated voltage. I didn't see that it adjusts or cuts off current based on temperature of a lithium battery.

If Classic + WBjr can be used to regulate maximum battery current, while supplying additional power for loads, that ought to be mentioned in description on web site as well as manuals. There was a time when PV was expensive, so we wanted to use all power harvested. Today, it is affordable to have more PV than allowed battery charge rate.

"Setting the WBjr current limit on the classic" - I can't find that document searching Midnight website even though I now know to look for it.
With internet search engine, I find it here (not displayed with Chrome, but using Firefox I can open it):

http://midniteftp.com/forum/index.php?action=dlattach;topic=3945.0;attach=6317

I also think Classic ought to be programmable to reduce charge current to zero at some (lithium) battery temperature. No mention of that, but would take care of low temperature protection for batteries with BMS lacking that. And I think it ought to be programmable with a current vs. temperature curve (not offered in any alternative energy systems I'm aware of, unless BMS requests that for those which communicate with inverter/charger)

https://www.midnitesolar.com/pdfs/Classic_Manual_Revision_22Jan2021_Final.pdf

http://www.midnitesolar.com/pdfs/10-264-1_REV_F.pdf

 

[Tecnodave]

I also think Classic ought to be programmable to reduce charge current to zero at some (lithium) battery temperature. No mention of that, but would take care of low temperature protection for batteries with BMS lacking that. And I think it ought to be programmable with a current vs. temperature curve (not offered in any alternative energy systems I'm aware of, unless BMS requests that for those which communicate with inverter/charger)

Coming soon now, stay tuned

 

[Tecnodave]

What that I do know is that boB and Robin are aware of the lithium battery issue and that is on the radar.
As far as disconnect at low temperature that is possible (maybe with some software tweaking) using battery bank temperature and the built in auxiliary contacts that can trigger external events based on the registers in the Classic’s

 

[MrM1]

What that I do know is that boB and Robin are aware of the lithium battery issue and that is on the radar.
As far as disconnect at low temperature that is possible (maybe with some software tweaking) using battery bank temperature and the built in auxiliary contacts that can trigger external events based on the registers in the Classic’s

I'm already triggering an external event on aux 1. It's called a water heater, controlled by an SSR, and triggered by battery SOC

AUX 2 is unfortunately already taken up by the WBJr

 

[MrM1]

After running my over paneled Midnite Classic 150 for about 3 weeks, I am very pleased with the production and outcome. And I think I've dialed in some safe limits.

Dropping the total Output Amps for the classic doesn't change my daily production that much, but makes a difference on FET and PCB Temps

Here's my setup

- Set output amps down from 94 to 88 amps output
- This lowers the FET Temps from around 85°c+ to under 78°c
- production drops from above 16.5kWh to 16kWh per sunny day.
- not a bad trade off.

What do you think? Is this acceptable FET / PCB Temps? below is at 1pm in Jan (today) with the no clouds. Classic is making 2400 Watts

 

[Wibla]

Looking good!

 

[Tecnodave]

Im running my Midnight Classic 150 with the amps limit set to 60 amps, If I need more than that I will add a third Classic 150, I never hear the fans running.......

5 years now and not one fail, shutdown, out of limits parameter.

Same with my Ultra high end sound system, never more than 50% power for more than a minute or so

 

[MrM1]

Im running my Midnight Classic 150 with the amps limit set to 60 amps, If I need more than that I will add a third Classic 150, I never hear the fans running.......

5 years now and not one fail, shutdown, out of limits parameter.

Same with my Ultra high end sound system, never more than 50% power for more than a minute or so

I wouldn't think you'd have to derate the classic by that much. That's nearly 30% with a 24v system . I would hope a classic running at 80-88 amps would be fine for a long time as it is advertised as 94 amps charging at 24v

 

[SpongeboB Sinewave]

I think MrM1 is right. You can crank down the current some but I'd try something in-between...

Try something like 75 to 80 amps at least.

It's fine for the fans to come on with increased temperature. But you can get an idea of higher output too.