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chris2 avatar image
chris2 asked

Multiplus II discharging battery under min. SOC

Hi !

My Multiplus II sometimes discharges the battery with 4W or 9W when min. SOC has been reached. It switches between 0W, 4W and 9W in undefinable minutes, or even hours. I´ve set the min. SOC to 15 % .

As I looked into the system after about 12 hours later, the battery has been discharged to 11 %.
I don´t know if it would go under 10 %, because system started to charge at 11% at morning.

I´ve installed the system just a few days ago, so I don´t have much experience with it so far.

Does anyone face the same issue ? Did I set somehing wrong in the setup ?

System is running in ESS optimized mode without battery life, no scheduled charging.

1xMultiplus-II 3000
Venus GX
2x Pylontech US2000 4,8kWh
AC coupled PV-Inverter Fronius IGTL 4.0 connected to AC-in



Thanks in advance for your help !

Regards,

Chris

Multiplus-II
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4 Answers
Daniël Boekel (Victron Energy Staff) avatar image
Daniël Boekel (Victron Energy Staff) answered ·

Hi @chris2

When the SOC reaches 5% below the set minimum SOC, it will recharge the battery back to the set SOC.

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jdoern avatar image jdoern commented ·

yes but why is the system going under the minumum soc limit?

we do not want the system to recharge the battery at night!

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thomasw-1 avatar image thomasw-1 commented ·

Is your GX-device powered by the DC-bus directly? In that case min 0,3kWh per day might be absorbed by GX directly, right? If you have no PV-supported charging during the day, the battery level gets reduced continously.

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jdoern avatar image
jdoern answered ·

We have exactly the same problem right now!

Is there a solution?

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Daniël Boekel (Victron Energy Staff) avatar image Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

It is normal behavior.

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jdoern avatar image jdoern Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

yes but can you explain me in detail why this is the normal behavior?

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seb71 avatar image
seb71 answered ·

All DC powered devices (inverter, GX device, etc.) you have are discharging the battery. If you have a BMS, that also draws some energy from the battery. Over time, it all adds up.

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athlonfx avatar image athlonfx commented ·

I noticed the same behavior in my ESS system (Multiplus-II GX, Pylontech 2x US2000) and wondered why. I could not find an explanation in the ESS manual. Thanks for the information!

@Victron: Please add this information to the ESS manual.

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DeVo Tyler avatar image
DeVo Tyler answered ·

Youre devices are always drawing energy day and night to stay powered on. draw less energy from the battery of get a bigger battery bank to compensate.

hopefully I understood you're question.

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