MPPT 75/15 Load Algorithm Questions

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ryanm asked Nov 25, '18

MPPT 75/15 Load Algorithm Questions

I have a MPPT 75/15 and I'm having issues with setting the load output. I select a user defined algorithm and set the low to 12.1v and the high to 12.8v (assuming that then Vbatt goes below 12.1v the load will shut off and when Vbatt goes above 12.8v it will turn back on). However, the next morning shortly after the MPPT turned on it shut off the load, it was 12.45v when the load turned off, Vbatt low in the log for the day is 12.44v. Why did the load go off?

I switched the high voltage to 12.4v (while battery is at 12.8v) and waited for the load to turn back on but it never did. I had to use AlwaysOn to switch the load (which has worked fine for the last few months). Am I misunderstanding how to use the load control?

MPPT Controllers

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mduncan commented · Nov 26, 2018 at 08:01 PM

I had the same issue many times trying to run a teardrop off the load inputs. They would randomly fick on/off repeatedly, at random, regardless if always on, or another algorithm was set. I had this happen on one mppt and returned it for a higher 20 amp and the same behavior. There are alot of posts on this without a definitive answer, and the documentation is sketchy. Hope @victron will chime in.

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mattsmith commented · Nov 27, 2018 at 09:08 AM

Nice to see I'm not alone. I have the 100/20 SmartSolar and it's doing similar. It's left alone with no load, everything turned off a the switch box and nothing showing as load in the app. But I come back and find the load is off and the only way to get back on is setting to always on. Frustrating as my $20 ebay nasty seems to work.

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ryanm commented · Dec 18, 2018 at 12:05 AM

@Guy Stewart (Victron Energy Staff) you mentioned that I should post this here and you'd explain in more detail how the voltage cutoff works.

Is there a reason why the voltage ranges don't seem to work as expected? Is there something else that can affect how the voltage cutoff works?

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Guy Stewart (Victron Community Manager) ♦♦ ryanm commented · Dec 18, 2018 at 12:13 AM

Hi Ryan,

I think Martijn is waiting for a response from you in his answer below with reference to this section of the manual - 4.2 Load output

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wkirby ♦♦ Guy Stewart (Victron Community Manager) ♦♦ commented · Dec 18, 2018 at 10:07 AM

This is interesting. I shall investigate this when I am at home (this weekend) and see if I can come up with any bright ideas.

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ryanm Guy Stewart (Victron Community Manager) ♦♦ commented · Dec 18, 2018 at 07:40 PM

I commented on his answer below a few weeks ago but no response. I'm using a VE direct cable so there is no jumper.

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paul-beard answered · Aug 04, 2021 at 07:57 PM

Similar issue here, perhaps. I noticed my load circuit was off two days in a row, not sure why. I never did anything with the jumper (it was across pins 2 and 3) but based on what I understand, I removed it and left everything else alone. When I found the load circuit off yesterday, I had to remove all the power from the charge controller to get it back. The panel was in full sun, middle of the afternoon, but the controller didn't switch load back on until I did that. Today, similar result. I moved the load directly to the battery and then after a while I reconnected it and all seems well. I'll monitor it today and tomorrow to see what happens. Perhaps I need to explore the manual settings on load on/off. It's worked fine without my meddling up to now.

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snowman commented · Nov 14, 2022 at 06:14 PM

Thanks paul-beard. Your details helped me after many hours of troubleshooting. Very similar issue I had programming the output on/off states, even after I pulled the (default) jumper (me bad). Solution was to remove power from the PV panel and the battery, then let the mppt 75/15 sit for 5 minutes. Powered everything back up and the "user defined" load output settings would then honor my pre-set values.

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Answer 1 · 2018-11-28T08:54:04Z

Martijn Coster (Victron Energy Staff) answered · Nov 28, 2018 at 08:54 AM

Hello Ryan and Matt,

About your load issue. Is the small jumper still placed on the VEDirect connector

see here for more information:
https://www.victronenergy.com/live/victronconnect:mppt-solarchargers#load_output

If this is the case please let me know here that the issue is solved.

best regards

Martijn Coster - Victron Energy

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ryanm commented · Nov 28, 2018 at 02:29 PM

Martijn,

No, I'm connected via a VE.Direct cable so there is no jumper pin.

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mattsmith commented · Dec 02, 2018 at 06:08 AM

I worked out my problem (and hanging head in shame) it was the blade fuse blown. Replaced and all working again.

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Answer 2 · 2018-12-19T18:44:45Z

mduncan answered · Dec 19, 2018 at 06:44 PM

So with the load jumper in place, any changes in victronconnect are ignored? It's not very clear what the correlation is. The issues I have seen in the past are that when the algorithm is set to ALWAYS ON, the load would randomly shut off. I've also had it flicker. Lightpost function disabled of course. I think something more problematic is at play here.

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Answer 3 · 2023-12-19T19:59:01Z

alecolin answered · Dec 19, 2023 at 07:59 PM

I have the opposite problem with two smartsolar... It never goes off even if I set off<13V and my battery is 12,4. My set up is with no jumper obv.. It is so frustrating.. Should I change again my smartsolar in your opinion?

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