The Limits Setting - In the Local App

Started by Matrix, May 12, 2018, 09:26:45 PM

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Matrix

Sorry if this has been asked before,  I did a forum search and did not come up with what I was looking for.

In the Local App (and I assume from the MNGP) there is a Limits setting. 

Using the Output Limits,  I realize that would lower the CC 150s Current Output ... But does that settings ...

1.  Lower the charge current to the battery

OR

2. Lower the battery charge current AND the Loads current

Example:  Lets say I set the limits to 35 Output amps.   If I then run a load during the day that exceeds that ... so 50 amps,  would it draw the other 15 amps off the batteries even though the panels would be able to supply the load?   

Is the setting just for charging or is it for the TOTAL output of the CC 150?
Grid-Assist Off-Grid
REC TwinPeak 2 285W 3S-3P 2565w-STC 1926w-NMOT Array / Classic 150 / Conext SW 4024 Inverter
Trojan L16H-AC 435Ah bank 4S  with 7' of 4/0 cable
24 volt system /  Need 3200Whs Daily
My System Install

ClassicCrazy

#1
Yes if you set the current limit to 50 amps that will limit the battery charging but also limit current available from PV for the loads to 50 amps too.
But after many requests Midnite fixed that - there is a way to limit only the charge current to the battery but make the full current potential available to loads.

The procedure for using that function is documented on the forums somewhere . I will try to look it up .

Larry
system 1
Classic 150 , 5s3p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system 2
 5s 135w Kyocero , 3s3p 270w Kyocera  to Classic 150 ,   8s Kyocera 225w to Hawkes Bay Jakiper 48v 15kwh LiFePO4 , Outback VFX 3648 inverter
system 3
KID / Brat portable

ClassicCrazy

You will find the pdf file document in the first post of this forum topic  called Global Current Limiting
http://midniteftp.com/forum/index.php?topic=3796.0

Larry
system 1
Classic 150 , 5s3p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system 2
 5s 135w Kyocero , 3s3p 270w Kyocera  to Classic 150 ,   8s Kyocera 225w to Hawkes Bay Jakiper 48v 15kwh LiFePO4 , Outback VFX 3648 inverter
system 3
KID / Brat portable

Matrix

Grid-Assist Off-Grid
REC TwinPeak 2 285W 3S-3P 2565w-STC 1926w-NMOT Array / Classic 150 / Conext SW 4024 Inverter
Trojan L16H-AC 435Ah bank 4S  with 7' of 4/0 cable
24 volt system /  Need 3200Whs Daily
My System Install

Matrix

 Why would the default value for current limiting be set to 30000?  Wouldn't that mean the default current value is 3000 amps?

Also, by limiting charge current does that cause the classic to build up even more heat? Even though I have my classic set on a very large 1 in heat sink, the size of the classic itself and I have a fan that comes on when aux one comes on to dump XS power to a dump load, I still get Celsius temperatures of about 62 264 degrees when fully charging and running the dump load during a full sunny day
Grid-Assist Off-Grid
REC TwinPeak 2 285W 3S-3P 2565w-STC 1926w-NMOT Array / Classic 150 / Conext SW 4024 Inverter
Trojan L16H-AC 435Ah bank 4S  with 7' of 4/0 cable
24 volt system /  Need 3200Whs Daily
My System Install

Vic

Quote from: Matrix on May 13, 2018, 05:49:11 PM
Why would the default value for current limiting be set to 30000?  Wouldn't that mean the default current value is 3000 amps?

Also, by limiting charge current does that cause the classic to build up even more heat? Even though I have my classic set on a very large 1 in heat sink, the size of the classic itself and I have a fan that comes on when aux one comes on to dump XS power to a dump load, I still get Celsius temperatures of about 62 264 degrees when fully charging and running the dump load during a full sunny day

Matrix,

Yes,   a Default of 30,000,   would equate to 3,000 Amps.   Some of the Defaults in the Classic appear to just chosen to make certain that a rarely-used function is far,  far from becoming active   ...   there might be some other reason that this is the Default ...

YES,   to a certain degree,   Limiting the Classic's output current  would reduce the loading on the PVs,  causing the Vin to the Classic to rise.   This rise in Vin would reduce the CC efficiency,   somewhat.   But the  increase in CC heating should not be a large factor.

This current Limiting,  is designed to Limit the amount of battery charge current,   not the maximum output current of the Classic.   This battery charge current limit is probably more useful in systems with multiple Classics.

FWIW,   Vic
Off Grid - Sys 1: 2ea SW+ 5548, Surrette 4KS25 1280 AH, 5.25 KW PV, Classic 150,WB, Beta Barcelona, Beta KID
Sys 2: SW+ 5548s, 4KS25s, 5.88 KW PV, 2 ea. Classic 150, WB, HB CC-needs remote Monitoring/Control, site=remote.
 MN Bkrs/Bxs/Combiners. Thanks MN for Great Products/Svc/Support&This Forum!!

Matrix

So if C/10 of my battery charge rate is 43amps,  but my classic can (and I have occasionally seen 63+ amps),  that is not a bad thing?   I was wanting to set a limit of 43 to keep the charge rate at or under C/10.  But perhaps with a single classic it is not that important?
Grid-Assist Off-Grid
REC TwinPeak 2 285W 3S-3P 2565w-STC 1926w-NMOT Array / Classic 150 / Conext SW 4024 Inverter
Trojan L16H-AC 435Ah bank 4S  with 7' of 4/0 cable
24 volt system /  Need 3200Whs Daily
My System Install

FNG

Matrix,
It really comes down to the battery, if the battery manufacturer says do not charge over xx amps then yes you should set the global current limit to xx and make sure a WBjr is in place. Setting the amp limit on the local app or MNGP in the limits menu will actually limit the classics output based on just that value, So with some loads on the system the battery will get less. This is whats nice about the global limit in modbus, it watches the actual battery and limits on that

Matrix

Thanks.  I am tinkering with the settings now (actually yesterday) and watching to see what it does. 

I absolutely love the Classic and the MN products.  I wish / hope they have a 4000 watt inverter at 48v when it comes time to replace my SW inverter.   My plan is to replace batteries and inverter in 2-4 years when the batteries are done.   Hopefully by then I can go all MN Solar gear. 

(well that is if code enforcement does not shut me down because I never did permit and never installed any form of Rapid Shutdown system - the $2k + addition to your system you will ever only need once ... if you ever need it)
Grid-Assist Off-Grid
REC TwinPeak 2 285W 3S-3P 2565w-STC 1926w-NMOT Array / Classic 150 / Conext SW 4024 Inverter
Trojan L16H-AC 435Ah bank 4S  with 7' of 4/0 cable
24 volt system /  Need 3200Whs Daily
My System Install

KyleM


Matrix

Quote from: KyleM on May 14, 2018, 01:59:51 PM

I was not here ... you saw nothing.
That reads like something printed on a B17 circuit board.  LoL !!
Grid-Assist Off-Grid
REC TwinPeak 2 285W 3S-3P 2565w-STC 1926w-NMOT Array / Classic 150 / Conext SW 4024 Inverter
Trojan L16H-AC 435Ah bank 4S  with 7' of 4/0 cable
24 volt system /  Need 3200Whs Daily
My System Install

Matrix

Quote from: KyleM on May 14, 2018, 01:59:51 PM

I was not here ... you saw nothing.

OK so I am seriously looking at this,   and I am seeing the array shut down receiver and I assume for off grid purposes that the transmitter shuts down all DC close the Inverter / Charge controller,  but where is the switch the fire and safety work would use to shut off the array and DC?    Does it use the bird house or something else or what am I missing? 

Also,   is there an SOB system setup for the AC side shutdown?   

Looking at the docs all I see is set up for Grid - Tie not off grid for the SOB
Grid-Assist Off-Grid
REC TwinPeak 2 285W 3S-3P 2565w-STC 1926w-NMOT Array / Classic 150 / Conext SW 4024 Inverter
Trojan L16H-AC 435Ah bank 4S  with 7' of 4/0 cable
24 volt system /  Need 3200Whs Daily
My System Install

FNG

The Little SOB system is designed to shut down just the PV array, NEC 690.12 Rapid Shut Down was only intended to shut down the wires between the pv modules and the MPPT device be it a charge controller or grid tie inverter. The Little SOB takes a transmitter ont he ground and injects a signal onto the dc lines and the receiver listens for that signal. No signal then it shuts off to be safe. In the case of a grid tie inverter the transmitter can be powered internally inside the inverter so the ac disconnect can be the initiator for example

Matrix

So for an off grid system,  it would seem that the SOBs might be able to handle the DC and then one would merely need a MN breaker and Birdhouse or some other switch to cut off the power to the inverter to power down the AC (and thus cause the SOBs to power off the Array)?    Seems for a system that is already installed this would eliminate the need to purchase a Disco closest to the array (already have a combiner) and another Disco closest to the CC?
Grid-Assist Off-Grid
REC TwinPeak 2 285W 3S-3P 2565w-STC 1926w-NMOT Array / Classic 150 / Conext SW 4024 Inverter
Trojan L16H-AC 435Ah bank 4S  with 7' of 4/0 cable
24 volt system /  Need 3200Whs Daily
My System Install

FNG

Matrix,
NEC code doesnt care about us shutting down the inverter, 690.12 only applies to the conductors between the pv modules and the MPPT device.

That said IF you wanted to disable the complete system, you would want to use the birdhouse system as a complete package