Author Topic: Using Classic aux settings to switch on/off grid input?  (Read 676 times)

jwb

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Using Classic aux settings to switch on/off grid input?
« on: May 12, 2019, 11:47:06 AM »
Hello - our Schneider SW4048 will overcharge our lithium batteries if we do not disable the charger manually. Could we use one of the Classic aux ports to control a relay that would switch on/off grid input? "Low bat disc" for Aux 1 looks promising.
Thank you!

SW4048 with Midnite Classic 200SL
2 Chevy Volt 48v 12s 50ah modules, voltage range 36-48v
2kw Panasonic HIT 6-panel array
grid support, no genny

boB

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Re: Using Classic aux settings to switch on/off grid input?
« Reply #1 on: May 12, 2019, 01:24:22 PM »

Pretty sure this can be done.

You will need some kind of large enough AC relay, either regular contact like relay or a SSR Solid State Relay to be controlled by the Classic's Aux 1 output.

I believe the mode(s) you would want to use is the Float mode that turns on when the Classic goes to Float from Absorb as your settings allow voltage and time wise, OR, the mode you were mentioning, Low battery cut-out.

Can't the SW4048's charge be adjusted as for time and voltage of its absorb charge cycle though ? 

K7IQ

jwb

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Re: Using Classic aux settings to switch on/off grid input?
« Reply #2 on: May 12, 2019, 04:23:33 PM »
Hello, and thanks for the quick reply. I will try your idea tonight when the batteries are down a bit. I had SW charger settings>lithium battery>control set to 2 stage no float. When I changed it to 3 stage, the absorb voltage option appeared. I set that to 46v, absorb time to 1 min, and absorb current to 10a. I'm not sure what to set float voltage and max current at, as I think we don't need to float our lithium modules. Anyway, limiting the SW charger would be a really nice safeguard, so thanks for the idea. Schneider tech support said there was no way for the SW to prevent overcharging in our scenario, but maybe they were erring on the side of caution, no battery fires, etc. ;^) Our BMS has an overcharge prevention feature good up to 15a, but hopefully we'll never need to use that.

I think we may still want to control grid input. The SW's AC support mode is supposed to allow self-consumption, but thus far it seems to pull very little from the batteries, despite decent L1/L2 load balancing. Also, the SW is designed to pull the first 2 amps exclusively from the grid as a safety measure to prevent any power from being fed back into the grid. During much of the year, our loads are below 2a, which means all that potential solar power is lost while grid input is enabled. I have been running downstairs a lot to flip our tandem breaker on/off, and even so we lose a lot of solar watts.

I'll look for an AC SSR in the meantime. We could disconnect L2 grid input and just put the relay on L1. That is, unless someone makes a tandem relay.

Thanks again!
SW4048 with Midnite Classic 200SL
2 Chevy Volt 48v 12s 50ah modules, voltage range 36-48v
2kw Panasonic HIT 6-panel array
grid support, no genny

Matrix

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Re: Using Classic aux settings to switch on/off grid input?
« Reply #3 on: May 13, 2019, 08:16:46 AM »
Do the Aux features work for the Classic when the sun is no out and there is no solar charge?  You are talking about controlling the SW charger using the Classics Aux.  I think in "Waste Not" once the sun goes down,  this Aux feature is no longer active in Auto mode because it has no voltage input to use as a threshold.  I guess other settings are different.

But with the SW,  would it be better to not use the Lithium battery type and instead use 2 stage and custom charge settings?  I have Pb batteries and use custom rather that the generic setting for this battery type.  I was not getting the charge results I needed.  I have not read much about the SW and lithium,  but seems custom charge voltage settings might help?     In custom you can use 2 stage and set bulk / absorb voltage and when absorb is finished either by time or Ah the charging will stop.  It will not go to float.   

Another way to limit charging in the SW to use the Charge Block Feature.  You can then tell the SW to charge for how ever long you want it to charge and then stop, regardless of voltage or amperage.  BUT using Charge block in this manner demands you as the user NOT allow the charge block time to expire,  or it will start charging again at the end of the charge block which is a 24 hour max period.  but I use charge block at night so I dont forget to stop the charging sometimes when doing Lead battery EQ.  I set it to stop charging after an hour,  so I can go check the Gravity levels and then start it again as needed.

The SW is quarky in some ways.  But I have found custom charging settings can do a lot of things.  Like I set all voltages to 32v (24v bank) for EQ,  and that way when doing a long EQ it does not have to go thru all charge cycles each time before going to EQ and does not stop every hour .  The SW only allows 1 hour EQs and then you have to start over going thru all charge cycles. 

But maybe Custom Charge setting and charge block might help you some??
« Last Edit: May 13, 2019, 08:48:38 AM by 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

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Re: Using Classic aux settings to switch on/off grid input?
« Reply #4 on: May 13, 2019, 08:47:43 AM »
AC Support Mode.  Drove me nuts for months as it would not do as stated in the manual.  But there are Several things you can or need to do to get it to work properly.   First, as to how it is explained in the manual - 3rd tier tech support told me The manual is wrong and never should have been worded the way it was,  (unless they updated it in the past 18 months to reflect Schneider's latest position about it).   Their FAQ page has recently posted an update about how AC Support mode is suppose to work.  And it actually does work pretty well when you get all conditions right. 

https://www.schneider-electric.us/en/faqs/FA332947/

But in short what needs to happen,  your loads need to be very nearly balanced across L1 and L2 and the loads needs to be higher than about 300W +/-.     Balancing loads is pretty much a dance on a razors edge especially at low Wattage.    I did my level best to balance my loads (not for odd moments of usage on a single circuit) but in general,  like fridge on L1 and common used  lights on L2 to get them to be as equal as possible.  Helped a little.  But what really Got it going well was finally getting an Outback PSX-240 Autotransformer (My set up here).    This causes the loads to "shunt" across the L1 / L2 of the SW so that where ever the load is coming from,  the SW tries to balance the output of it's L1 and L2 to supply that load.  While not perfect,  these 3 ideas - Trying to improve on my usage following Schneider's FAQ page,  Load balancing and the Autotransformer - pretty much solved my AC support dilemma.
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

boB

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Re: Using Classic aux settings to switch on/off grid input?
« Reply #5 on: May 13, 2019, 06:45:48 PM »
Do the Aux features work for the Classic when the sun is no out and there is no solar charge? 

Yes, the Aux features work after sundown.   Especially the ones that reference voltages, either battery or PV input.

They have to work 24 hours a day because of external sources like hydro or wind turbines or other generators.

K7IQ

jwb

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Re: Using Classic aux settings to switch on/off grid input?
« Reply #6 on: May 16, 2019, 11:06:58 PM »
Thanks, boB and Matrix. It's good to know that the Classic's voltage-related aux functions keep working 24h per day. I will be on the lookout for an appropriate relay to use for controlling grid input to the inverter (maybe solid state, 12v, 400amp?). I'll also try to confirm which aux port and config options would work best to control the relay. I'm guessing the Classic manual would be a good source for info on aux options and configuration.

On the SW, I tried to implement boB's idea about setting absorb voltage, but charging continued above the absorb voltage and time limits. I also tinkered with Custom charging settings but wasn't able to find any way to limit charging there either. However, charging stopped when SOC reached the high SOC limit set in AC Support -- hip hip hooray. Thus far AC Support SOC has been the only voltage-related control I've found to limit charging on the SW. Charge block is a nice option, but the SW could still overcharge during the charge block open window if batteries were somehow already fully charged. Also, if it got cloudy while a bunch of loads were running, charge block "off time" might allow low-voltage inverter shutdown, thawed freezer, etc. It's quite a puzzle.

Several weeks back I read MrM1's solar-electric posting about using an autotransformer to balance loads on the SW. For now, we're trying to keep our loads minimized and balanced, but we could benefit from an autotransformer once we add air conditioners and dehumidifiers to our solar load center.

AC Support SOC limit, charge block, and using an autotransformer could all serve as safety nets, but it still seems like we need to control grid input independent of the SW. I'll share what I learn about controlling a relay with the Classic aux port.

Thanks again!
SW4048 with Midnite Classic 200SL
2 Chevy Volt 48v 12s 50ah modules, voltage range 36-48v
2kw Panasonic HIT 6-panel array
grid support, no genny

boB

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Re: Using Classic aux settings to switch on/off grid input?
« Reply #7 on: May 16, 2019, 11:31:14 PM »
OK, sounds like you're on your way, JWB.

I don't understand though why the SW would allow the battery voltage to rise above the preset absorb voltage unless the Classic 200 is either doing it or the SW is maybe not working correctly.

What is the absorb time set for ?  Many lithium batteries want charging to stop when a certain voltage is reached.  What if you set the absorb time for almost zero minutes ?  And set the Float voltage to a very very low voltage ?

There is also an LBX mode which I think, if enabled, will turn off the grid input unless the battery voltage drops to some really low voltage.  You might try LBX.  Just remembered that.

boB
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Matrix

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Re: Using Classic aux settings to switch on/off grid input?
« Reply #8 on: May 17, 2019, 08:32:02 AM »
Yes that seems like odd behavior that the SW is charging above the set Bulk / Absorb / Float voltage.  I have not experienced that except when I had the bulk voltage set to 32v in order to try and force the SW to stay in bulk loner - Because the SW seems to terminate Absorb charging too early and/or very quickly regardless of settings.   The manual really does not state it,  but I assumed the reason there even is a Bulk voltage setting  is to set a crossover point from Bulk to Absorb (as bulk slowly increases voltage).  What would happen is the SW would still transition at about 29-30 volts in what the SW was reporting ("I'm now in absorb"),  but then for the first 10 minutes of Absorb the voltage would continue to rise until it hit my Bulk hi voltage and then quick settle into my Absorb voltage.  But I've never experienced it going above or over the voltage set points. 

So with the SW charger,  I have not experienced it charging at volt levels higher than where it is set.  And if  I set absorb to 29.6 (and there is no compensation for temp),  it actually charges at 29.5v according to the classic and my Meter - Lower that what it is set at.

Actually I find the SW's charger to be it's weakest Link and worst performing feature.  It seems to be a flaky and finicky charger at best.

Any chance you are trying to charge in the day time and the classic is on and charging too?  I have experienced this causing slight voltage overages.  If so you might want to set a charge block to only let the SW charge at night. 

Also Not sure what you are meaning when you say "AC Support SOC Limit"?  Do you mean AC Support Voltage?  If so that really does not limit charge (although it kinda does because the charger will not operate when AC support is enabled and the battery voltage is at or above the AC Support set voltage),  but the AC Support Voltage setting is for the user to set the cross over point between Battery Usage and Grid Usage.  When in AC support, the SW will share the load between Grid and Battery.  And the higher the battery voltage,  the more the battery supplies the load (if the loads are balanced and greater than around 300W),  but as the battery voltage reaches the user set AC Support voltage,  the SW transitions from Battery for loads to Grid.    As the voltage drops at or below user set AC Support voltage,  the SW stops supplying loads from the battery all together.  Charging from the SW will start as the battery voltage gets below that  set AC support voltage - problem with that is ... what would pull the voltage down lower once loads are off the battery?   If you are using it as a charge limiter,  it is set to hi to actually be useful as AC support except when a solar array is providing more power than is needed to charge the batteries.  Yes it will  work when your array is providing power and the battery voltage is in higher charge levels above your set AC support voltage,  but AC support will do nothing for supporting loads once the battery voltage drops below your AC Support voltage setting   if you set it at charge voltages to limit SW charging.
« Last Edit: May 17, 2019, 08:34:14 AM by 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

jwb

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Re: Using Classic aux settings to switch on/off grid input?
« Reply #9 on: May 18, 2019, 12:42:25 AM »
Hello and thanks again for considering our quandary. Even though absorb time is set for 2 minutes, the SW charger kept going until it reached the AC Support SOC high limit. At that time there was no solar input. We have a Conext battery monitor, which allows battery SOC settings to be used for AC Support. Ironically, we had originally planned to also have a Schneider charge controller too (which would have allowed for Enhanced AC Support) but our 330w HIT panels required a higher voltage CC. So now we have the Classic 200 SL. Compared to our SW and the unorthodox batteries, the Classic has been the shining star of our entire system, thanks to both the unit itself and the tech support that helped us get it configured.

I was not able to find the LBX setting anywhere in our SW options. Maybe it was active in earlier firmware releases.

OK, thanks again!

bee88man

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Re: Using Classic aux settings to switch on/off grid input?
« Reply #10 on: May 18, 2019, 09:49:13 AM »
Finding a 400 amp DC contactor would be hard enough task...to find 400 amp SSR and giant heat-sink could be way more difficult and a bunch of $$$ also.

boB

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Re: Using Classic aux settings to switch on/off grid input?
« Reply #11 on: May 18, 2019, 06:04:09 PM »
You know....   The SW you are talking about might just be a non-Trace Engineering SW4048 in which case all bets are off for anything it might be doing that is strange.

Is this one of the old white SW4048 inverters ?  Weighs about 100 pounds ?   With a 2 line LCD with 4 or 5 different colored buttons underneath and the plastic surround sporting a "HAL 9000" ???   If it says HAL 9000 then it is a Trace Engineering style SW4048.

Seems everybody and their brother nowadays uses that model number if it is a Sine Wave inverter at 4000 watts and 48 volts.

boB
K7IQ

Vic

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Re: Using Classic aux settings to switch on/off grid input?
« Reply #12 on: May 18, 2019, 07:29:48 PM »
Hello - our Schneider SW4048 will overcharge our lithium batteries if we do not disable the charger manually   ...   

Hi boB,

Assume that the Schneider reference must mean that it is not a Trace,  or Xantrex Inverter   ...

Know that Matrix is definitely running the Schneider.

I know nothing of these Schneider units,   other than,   a number of users of them seem to be a bit (and at times,   more than a bit) disappointed with how well it does things,   especially when interacting with the Grid.

73  ...   FWIW,   Vic
Off Grid - Two systems -- 4 SW+ 5548s, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 3X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  Thanks MN for Great Products/Service/Support!

boB

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Re: Using Classic aux settings to switch on/off grid input?
« Reply #13 on: May 18, 2019, 09:58:45 PM »
Too bad they took out some neat old features that they inherited from Xantrex and Trace.

But it should regulate.

Maybe there is a battery temp sensor that is raising the absorb voltage

K7IQ

tecnodave

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Re: Using Classic aux settings to switch on/off grid input?
« Reply #14 on: May 18, 2019, 09:59:16 PM »
It would be easier to understand if people refer to the Schneider 4048 as the "CSW4048" , really a 3848. and the Trace.  4048 as the "SW4048"..... it is confusing and misleading at times to know one from the other.  Too bad Schheider could not do it as well as Trace did way back then......

What I really don't understand about Schneider is their statement is that the CSW4048 is the replacement for the TR line which it is not related to. (wasn't it modified sine wave or did Schneider get that wrong too)
« Last Edit: May 18, 2019, 10:04:51 PM by tecnodave »
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