• Multiplus II Inverters

  Why is my Victron Multiplus 3000VA Inverter not going into Float Mode?

  Posted by popo on January 14, 2024 at 8:06 pm

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  Hi guys, I have a twofold question.

  I have built two independent systems: – I’ll label and refer to them as SYSTEM1 and SYSTEM2 for clarity.

  Both have been running without issue for months and I am very happy, but these related questions have been testing my OCD lol!

  SYSTEM1 (2x Parallel Batteries – older battery firmware):

  • Grid: 230V (No ESS)

  • Inverter: MPII 3000VA 48V (2400W)

  • Battery: 2x Bluenova 5.2kwh BP rack mount batteries with internal BMS (in parallel)

  • Cerbo Firmware: v3.12 with GUIMods

  • Inverter Firmware: xxxx508

  • Battery Firmware: v0.5

  SYSTEM2 (Single Battery – newer battery firmware):

  • Grid: 230V (No ESS)

  • Inverter: MPII 3000VA 48V (2400W)

  • Battery: 1x Bluenova 5.2kwh BP rack mount battery with internal BMS

  • Cerbo Firmware: v3.12 with GUIMods

  • Inverter Firmware: xxxx508

  • Battery Firmware: v0.7

  Both are wired and fused in a very similar manner.

  Both have the same voltage settings in MPII (using MK3 USB):

  • Charger: Absorption Voltage = 55V

  • Charger: Float Voltage = 54V

  • Charger: Repeated Absorption TIme = 1h

  • Charger: Lithium Batteries = Enabled

  • Grid: Wide Frequency Range = Enabled

  • Grid: UPS = Enabled

  • Grid: AC Low Disconnect = 200V (230V – 30)

  • Grid: AC Connect = 230V

  • Grid: AC High Connect = 230V

  • Grid: AC High Disconnect = 250V (230V + 30)

  • Inverter: DC Low Shutdown 48V

  • Inverter: DC Low Shutdown 48V

  • Inverter: DC Low Restart 49V

  • Inverter: DC Low Pre-Alarm 51V

  • Inverter: AES = Disabled

  • Inverter: PowerAssist = Disabled

  • DVCC (Cerbo): Max Charge Voltage = 55V

  Question 1:

  Both systems never go into Float mode and only ever reach Absorption, sitting just over the 54.5V mark. Is this normal? My understanding is that they are supposed to hit float after absorption when they reach close to 100%. I do remember reading somewhere that float is more necessary for Lead Acid than LifePO4, but unsure of the reason or the truth to this?

  Question 2:

  SYSTEM1 only ever reaches 99%, while SYSTEM2 reaches 100%. Why is this happening? I see that the SYSTEM2 BMS shows the actual cell ranges next to their cell Voltages, whereas SYSTEM1 does not. Possibly due to it being an older firmware of V0.5, or because it has 2 batteries?

  Thanks!

  popo replied 5 months, 3 weeks ago 1 Member · 0 Replies
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