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Don Sutton avatar image
Don Sutton asked

Flooded Area, Issues with running on Battery/MPPT

I have a remote fishing cabin that has been turned in to an island due to river flooding in Texas. I have a Victron system powering my emergency systems and acting as a UPS when the grid is active. The grid has been down for almost a week and I’ve exhausted all the propane for the generator. There is no way to get to my Cabin until the water recedes, likely next week. The system is connected to 2 Victron MPPT’s and 1kw of solar panels and two 400ah batteries.


I lost connectivity early Friday (3May) morning and got a “Low Battery on VE.Bus System” alert, then warning, before it eventually shut down. On Sunday, the system unexpectedly came back online with the batteries at 27.8v. It ran all day Sunday and then threw a “low battery” alert early Monday morning and it’s been offline again since. I was expecting the MPPT/Solar to bring the batteries and system up every day but this does not seem to be the case.


The system went offline Friday (3may) morning. We had partial sun on Friday and Saturday. Good sun on Sunday when the unit suddenly came back online around 1pm. It went offline again early Monday morning (6may) and did not come back online yesterday despite a full day of sun. I’m hoping it comes back today.

I can only get to this device remotely through VRM and remote console, assuming it comes back online. Are there any settings I can change or do remotely to have the system come back online daily despite the battery state? Can someone give me a potential explanation of what I’m experiencing now, did I set this up in a way that requires the batteries to be fully charged before the system comes back online?


Also, my batteries have their own BMS in them. They’ll turn off before they get too low, can I turn off all the low battery safety features of the Victron components? My desired outcome is that the system comes online daily with the MPPT fed sun or through what’s left of the batteries. The sun is typically enough to carry the system throughout the day and put a nice charge on the batteries.


Victron MultiPlus 3000va 24v, Cerbo GX, (2) SmartSolar MPPT, (2) 400ah 24v Big Battery LiPo4 batteries. The system typically acts as a UPS to runs power for my network electronics, security cameras, split unit, refrigerator, and Starlink. AC input is connected to an AutoTransfer switch that is fed from the grid (primary) and generator (secondary). I need the system to come on and go off with the sun if possible? I big draw on the system is the refrigerator and I have no way of disconnecting that at this time. It was running at about 230w on Sunday when it came back online. There is a guy up there, if I can get in touch with him, I’m going to see if he can go over and unplug my refrigerator, I have a wifi enabled plug I’ll put on that to load shed in the future.

Any help would be appreciated. Thank you, Don.

Multiplus-IIoffgrid
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3 Answers
Michelle Konzack avatar image
Michelle Konzack answered ·

Maybe you should switch off the MultiPlus-II temporarily for a day or so to give the Batteries a higher charge.


Maybe you should switch on the MultiPlus-II at 04:00pm to 19:00pm and then again from 08:00am to 10.00am which should cool the Fridge enough but save you Enery while in Emergency Status.


You have definitively not enough Solarpanels for you situation.

Since you have a 24V System, which SmartSolar do you use?

Are the solarpanels in parallel or in series?


With 24V I would suggest that you have at least 60V Vmpp or better 100Vmpp because even with very little sun, especially in the morning or evening, it help very much.


This is my experience from Estonia where we have VERY often cloudy weather and the Winter is very dark. This is, why I switch to more expensive SmartSolar 250/100 with 5 solar panels 550Wp in series and strictly oriented it to the west. It give around 3 times more energy as the SmartSolar 150/70 with 3s2p and 1860Wp in total.

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Alexandra avatar image Alexandra ♦ commented ·
Without previous wiring there isn't a way to do it time based. Unless you want to try program a node red control over the internet after loading venus os large?
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Michelle Konzack avatar image Michelle Konzack Alexandra ♦ commented ·
You can get for under 20€ week-timer (24V DC directly from the Batteries) from China and simply control the "Remote Input" of the MultiPlus or the PowerSocket of the Fridge. It is not VRM/Remote controled, but it would work.
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Don Sutton avatar image
Don Sutton answered ·

@Michelle Konzack I have two Victron MPPT controllers. One is a Smart Solar 100 30amp connected to (4) 100w panels. The other is a Smart Solar 150 35amp connected to (6) 170 watt panels.

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Don Sutton avatar image
Don Sutton answered ·

My system came back online this afternoon. I made some changes to the system, mainly around the battery voltage and sync'ing the %. Somehow my battery settings were changed (this could have happened a long time ago, this is a set it and forget it system). I had significantly less charge than I assumed looking at the %. We'll see what happens over the day and the coming days. I now have a better idea of what's going on. I got someone to unplug the fridge. Hopefully we'll get some more sun soon. The good news is, the water is down 2" from yesterday. Thank you for your help.

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