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saxofon avatar image
saxofon asked

Solar charger doesn't provide idle power on cold days

Hi,

sunny-cold-day.png

As can be seen, it is a sunny but cold day still here in Stockholm area.

A minor issue now is that the solar panels could provide energy for the current loads but as the BMS prohibit charging due to below 5 degree celcius (which is a correct thing todo :) ) the MPPT is cut off via a Cyrix-Li, controlled by the BMS.

This is not a bug then as it is per design in my case.

Now, if I would like to be able to use that possible energy contribution from MPPT in these cold days what would the Victron solution be? I guess skipping the Cyrix-Li relay and then assume that Cerbo (or if it is the Multiplus II really via Cerbo that controls this stuff, unsure about this part, with all the assistants etc) will limit the MPPT to provide only the needed load energy?

But then I don't have protection in case there would be some error in cerbo, communication lines or whatever and the MPPT could simply blast all it can to the battery even if it would be 100% full. I have the Multiplus connected directly to battery sort of (as there is no separation here between load and charging and there is no standard way to protect us here really via a "stop charging relay" to my knowledge) but via breakers, fuses and such of course. This is not really a big problem since I'll be in boat when using shorepower (but well, never do connect to shorepower really since solar energy is enough so this is one of the least used parts of my Victron system :D )

What would be the optimal setup here?

BR,

Per

MPPT ControllersBMS
sunny-cold-day.png (244.2 KiB)
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Maybe if there are load connections on the MPPT, they won't shut down. But just guessing.
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Please make a full list of your components in your system.
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1 Answer
Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

The battery says it is 2°C, if you have Victron Smart lithium batteries they stop charging below 5°C. You have to warm up the batteries a little bit.

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I'm ok that it can be too cold to charge the batteries. But I would like anyway to be able to use the solarpanel energy to drive the system need as far as it can, so that is what this usecase is about... not charging batteries but to be able to use the solar energy for driving load during cold time.
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