Multiplus II won’t leave Bulk (ESS + Pylontech)

Q&A and troubleshooting
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1

Hi everyone,

I could use some help with my setup – been stuck on this for about a week now.

Issue: My Multiplus II stays in bulk mode even though the Pylontech batteries are already full and showing Idle (around 50.01 V, 0 W). From what I understand, it should normally move on to absorption and then float, right?

Setup:

  • Multiplus II 48V/5000VA/70A

  • 2 × Pylontech US5000 (4.8 kWh)

  • Lynx Distributor

  • Cerbo GX mk2

No Victron BMS, just using the built-in Pylontech BMS over VE.Can.

Settings (based on Victron’s guide):

  • ESS mode: Optimized (with BatteryLife)

  • DVCC: Max voltage 52.4V, STS/SVS/SCS all off, BMS control = Pylontech

  • Absorption: 52.0V, 1h

  • Float: 51.0V

Am I missing something in the configuration, or misunderstanding how this should behave?

I can post screenshots from VE.Configure or the GX console if that helps.

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Thanks in advance!

2

I see you have a minimum soc set at 99% thats why it stays on “charging/bulk”

did you missed that setting or was that on purpose?

3

Hi Mark,

Well, that’s only partly true. I’ve tested it before.

Whenever I set the SOC to 100%, the inverter does go into Absorption, but the batteries stay stuck around 98–99%.

Also, they never really switch to Idle. The inverter just keeps trying to charge and discharge them constantly, even after a whole day.

But shouldn’t I be able to set the inverter to any SOC I choose and still have it work properly? Why does it have to be set at 100%?

Thanks!

4

If you would like the system to act as ess, you should set a lower minimum soc

When you want the batterys to be full and only use them for backup, set it to keep batteries charged

with a new system it can take a while (days/weeks) for all batterys to balance, if its a new system setting it to keep batteries charged will also help to balance

5

I am going to assume this is a new set up.

The batteries are at 99% at 50v. There is something is not happy there.

Since you have programmed as recommended i would remove the voltage cap. leaving the voltage cap on can cause problems. Sometimes it is best to leave the batteries to sort themsleves out.

Have a look at the CCL they are requesting in the parameters. If it is not 0A they want to be charged.

Basically leave them to charge up fully over a day or two. Let them settle down.

Not always the case on an ess system with bms control.

They are trying to balance. They are able to sort themselves out. So leave them to do so.

As a side not ESS is in bulk production when solar is covering loads thebulk state does not necessarily mean the battery bank is in bulk.

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