How to limit SOC while being connected to grid

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piraya asked Dec 7, '21

How to limit SOC while being connected to grid

Boat: Quattro+CCGX+Lithium+Genset+Happy captain

When running generator on auto start (from CCGX), I can set CCGX to which SOC genset shall start and stop. Hence I can keep batteries always between f.ex. 20%-80% in order not to stress the batteries.

How can I set the same limitation when connected to shore? You know, like my Tesla, it strongly recommends not to charge over 90% in daily use to preserve battery life. The solution, if there is any, should be easy to override, as you once in a while suddenly want to charge to 100% again.

(The problem is the same with the boat engine, but with my 1000Ah lithium bank the engine rarely achieves 100% anyway.)

SOC

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Answer 1 · 2021-12-08T11:27:42Z

JohnC answered · Dec 08, 2021 at 11:27 AM

Hi @Piraya

There's probably several ways to do this. Given the Quattro has switching control of ACIN (1 or 2), then you could use Assistants. These are a bit clunky to change about regularly, so if you're happy with doing it from the GX, then maybe like this..

Thinking aloud now, and presuming you're happy with switching off the genset autostart externally when you plug in shore.

Run another wire pair from the GX relay to an Aux port in the Quattro. Set up Programmable Relay asst to read that Aux and signal General Flag asst, which is set to Ignore ACIN (1 or 2, whichever shore is on). Needs to be set up in reverse so it Ignores ACIN when you don't want it, when SOC is ok.

So now instead of starting the genset the GX will stop ignoring ACIN.

If you're new to Assistants you'll need to brush up a little.. https://www.victronenergy.com/live/assistants:start

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Answer 2 · 2021-12-08T11:52:02Z

piraya answered · Dec 08, 2021 at 11:52 AM

My Quattro has control, this is a standard installation that follows the installation manual, i.e. genset on ACIN1 and shore on ACIN2. But I do not want to stop charging by ignoring the shore input, I want to continue to use the shore to power all other equipment, I just want to stop the charging when batteries reach 90 % or so. Furthermore, I do not want to switch on and off the genset auto start functionality each time I connect to shore, I am looking for a hazzlefree boating life (which is why I use the auto start in the first place). So I was hoping that Victron (as being one that particularly should care about battery health) had an easy available parameter to limit SOC when connected to grid.

I could accept an advanced solution if it is a one-time operation. Maybe the most easy way is to set the Quattro charge voltage as low as 13,8V or 14,0V (which corresponds to a 90% charge level at my batteries), but will my charging then take longer time? And is it pretty tricky to set back to 14,6V now and then during the summer?

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baard commented · Jun 04, 2022 at 07:59 PM

Hello,

I am looking for a solution for the same problem. Did you ever find out how to achive this? I have MultiPlus, MPPT PV, BMV-712 and Cerbo GX on board the boat.

Thx
Regards, Baard

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Answer 3 · 2023-03-20T08:00:54Z

solaralpin answered · Mar 20, 2023 at 08:00 AM

I am facing the same problem for my home batteries. I want to limit the SoC to max. 80% to not stress the batteries. (Cerbo GX, Multiplus 2, Pylontech batteries)
I can't believe, Victron has not implemented this feature?!

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johnone commented · Mar 20, 2023 at 09:02 AM

If your Pylontech batteries are US3000C, US5000C or similar, where are you getting info which says don't charge above 80%? Isn't the point of these batteries that they are fine to use within a range of 10% to 100%? I'd be interested to see any data which says otherwise. Thanks

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nickdb ♦♦ commented · Mar 20, 2023 at 09:53 AM

It is neither necessary nor advisable on those batteries. If pylon wanted you to do that it would be stated in the manual. All you will do is create the conditions for an unbalanced battery.

This battery myth does not apply to commercial battery packs, in which the bms and architecture already keeps the battery in an optimal condition. That is why victron does not have this “feature” as it is broadly not required by the industry and manufacturers.

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Answer 4 · 2023-03-20T11:55:23Z

bigbadbob76 answered · Mar 20, 2023 at 11:55 AM

Simply set your charge absorption voltage slightly lower, this will limit your maximum charge percentage.

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