question

hobohome avatar image
hobohome asked

How to start equalise - Smart Solar MPPT?

Hi,

I am trying to start a manual equalise on my flooded lead acid battery bank.

My off-grid system:

3 X Smart Solar MPPT (East,North & West arrays)

1 X Quattro 5kva 48v

1 X Venus GX

All devices are running the most recent firmware (as at 10/03/19)

With the three controllers in FLOAT, using the Victron Connect app on my phone, I start a manual equalise on each of the controllers. They all flash the blue and orange LEDs to show equalise mode is active, but the voltage never rises above the set absorption voltage.

The settings are the same on each of the controllers and are shown below.


Also below are the graphs showing the reported controller state (all three are the same) and also the reported system voltage and current. I tried to start the equalise at midday.


Any help or suggestions would be gratefully received.








offgridsmart solar set-up helpDVCCequalisation
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2 Answers
JohnC avatar image
JohnC answered ·

Your mppts are switching to ESS mode, and that shouldn't be happening. There was a (very) brief discussion just yesterday re this and a relationship to DVCC. Try turning DVCC off.

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hobohome avatar image hobohome commented ·

Thanks, I will try that.

Does turning DVCC mode off mean that I will lose the max battery charge current setting?

Also, will I also lose the temperature compensation provided by the Venus GX sensor?

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JohnC avatar image JohnC ♦ hobohome commented ·

You may lose the charge setting, but shouldn't the temp. But I don't know, hey. If this is a bug, and you haven't deliberately loaded ESS, who knows?

Offgrid, you 'shouldn't' have ESS, but why is it being reported? Guinea pig stuff methinks. See how you go and report back. Good luck too.

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boekel avatar image boekel ♦ JohnC ♦ commented ·

@JohnC
MPPT devices show their state in VRM as 'ESS' as soon as they're in DVCC mode ('network mode in the MPPT status')

It can be a bit confusing yes.

unfortunately I can't help with the original question..

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mvader (Victron Energy) avatar image mvader (Victron Energy) ♦♦ boekel ♦ commented ·

Hi; I fixed that confusion; its now called Ext. Control in VRM; rather than ESS.

What it means that the mppt is not following its own charge algorithm program.

Thanks for highlighting this.

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hobohome avatar image
hobohome answered ·

Ok, so I think I have figured out what is happening here.

I turned of DVCC then waited until all three controllers were in FLOAT. I then told them to EQUALISE - they responded obediently by flashing the orange and blue LED's. For one hour, the voltage remained around 58.4v - so I re-read the smart solar manual. I also turned DVCC back on because as @Boekel pointed out ESS= DVCC in VRM.

Now I think the issue where the battery fails to reach the EQUALISE voltage is that the 25% of BULK current limit is stopping the battery terminal voltage from rising to the EQUALISE voltage. This seems to be because that 25% limit is NOT battery charge current but controller output. So, in the case of my 150/100 controller, it is enforcing a limit of 25amps from the controller - if my loads are using 20amps, that leaves just 5amps to charge the battery bank and force the terminal voltage up to the EQUALISE setting. Simply just not enough.

This is quite sad as one of the reasons that I decided to use Victron gear was because I thought that the Venus GX would resolve issues like this (as it can see/calculate the real battery current) by bringing all known data together to make truly system wide intelligent decisions.

I can only hope that the vision for the Venus GX going forward is to resolve issues like this and perhaps even have true multi controller synchronised charging. Seems far more important to me than getting something as obscure (but very interesting) like Node Red working on the Venus GX. I, for one, would much prefer to be able to correctly charge and equalise my battery bank!

I'm now considering the possibility that I will have to change the absorption voltage every month to actually perform an equalise.

Anybody got any better ideas?

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boekel avatar image boekel ♦ commented ·

Hi @Hobohome, sorry not an answer, but a question!

Do you / can you start equalising from the quattro when it has no AC-in? is there a generator available?
I don't have experience with lead-acid and DVCC (only building lithium systems for a while) so my comment might not be worth much ;)

What I do know is the low current for equalizing is for a reason, and with PV systems it is often difficult to fully charge a lead-acid battery during the day, let alone equalizing after that.
So not the answer you want, and you might have plenty solar available for equalizing but maybe a work-around (for now?) is to use a generator for equalizing. Monthly gen-test / equalize?

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