question

sdc88 avatar image
sdc88 asked

SOC drops slightly every 7 hours

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I recently install 3 x 4kw new BYD LVLs to an existing system on grid that had 3 x 4kw BYD LVLs so a total of 6 (two towers of 3) with a Victron Quattro 48/10000/140. I since I installed the 3 extra batteries my system as been slightly dropping SOC to 99.5% every 7 hours without any change in load or mains loss. What settings can I check to see why this is happening all of a sudden? Let me know if you need further screen shots of any parameters.


Update: I have fully bypassed the inverter so there are no loads and it still dropped SOC slightly on the 7 hour mark and went into bulk charge.


Update 2: did a discharge test all worked ok, went down to 20% SOC, charged back up to 100% and it went back to every 7Hrs issue again. At a loss.

battery chargingVictronConnectSOCBYD
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5 Answers
nickdb avatar image
nickdb answered ·

Probably just the new batteries trying to balance.

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sdc88 avatar image sdc88 commented ·
I probably should of mention the new batteries have been in for over a month now.
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nickdb avatar image nickdb ♦♦ sdc88 commented ·
Some batteries can take a while to sort themselves out, depending on use.
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sdc88 avatar image sdc88 nickdb ♦♦ commented ·
Yeah will see, basically just sits there as a UPS, I might discharge them and have them charge up again to see if this helps.
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nickdb avatar image nickdb ♦♦ sdc88 commented ·
It sometimes helps to run them down nicely and bring it back up to charge.


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sdc88 avatar image sdc88 nickdb ♦♦ commented ·

@nickdb no luck

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thanar avatar image
thanar answered ·

What is the "repeated absorption interval" value set to, under "Cherger" tab on VE.Configure 3?

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sdc88 avatar image sdc88 commented ·

victron-3.png

It is set to 7 days @thanar

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sdc88 avatar image
sdc88 answered ·

@Alexandra seems like you might know what’s happening here?

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Alexandra avatar image Alexandra ♦ commented ·

@SDC88

Are you running ESS. are you on keep batteries charged? Or set at 100% in case of grid faliure?

Do the drops coincide with solar day start/end? And as guys have mentioned cell balancing? It is a strong candidate here.

Do they all discharge ok and charge up ok as a bank?

BYDs BMU uses the lowest battery SOC, so it may just be one or two sorting themselves out.

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sdc88 avatar image sdc88 Alexandra ♦ commented ·
Not running ESS


Drops are happening every 7 hours but not exactly, sometimes at 3am in the morning, and even without any load on the inverter.


Currently performing a discharge it’s been 12 hours will report back once it’s charged but it’s looking ok at the moment, anything in particular I should be looking at?

If it’s just the batteries balancing, how long can this take? It’s been happening for over a month since the second bank was installed?


Appreciate your support.

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sdc88 avatar image
sdc88 answered ·

@WKirby you have any idea what is happening?

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sdc88 avatar image
sdc88 answered ·

@BYD_serviceyou have any idea what is happening?

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byd-service avatar image byd-service commented ·
Both the batteries and Venus device consume energy to stay on, as you can see the consumption is really low. As soon as the voltage decreases below the absorption voltage then it goes into bulk.


On the other hand, in order to have the most accurate SOC it is recommendable to cycle the batteries. If you´re using them for UPS you might want to still set 10-20% for self-consumption and leave the rest as backup.

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sdc88 avatar image sdc88 byd-service commented ·
Thanks for replying @BYD_service, so you’re saying in absorption with no loss of mains the battery voltage will still drop?
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byd-service avatar image byd-service sdc88 commented ·
One the battery reaches soc 100% it will change CCL to 0. So even if it is in absorption charging will stop until soc decreases below 100% and it sends a CCL different from 0.
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sdc88 avatar image sdc88 byd-service commented ·
So my concern is null and void, it’s basically operating as it should be. @BYD_service
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nickdb avatar image nickdb ♦♦ sdc88 commented ·
It is how the BYD's balance, have a new one that does exactly the same. The more it is left to balance the more it settles.

You can correlate the behaviour to the max cell voltage, CVL and CCL.


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