SYSTEM SHUTTING DOWN ON “LOW BATTERY” AT 13.0–13.2V

Q&A and troubleshooting
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1

System:

  • Victron Multiplus II 12/3000/120

  • Victron SmartSolar MPPT 150/100

  • Victron BMV battery monitor

  • Victron Lynx Distributor

  • 6 × Battle Born 100Ah LiFePO₄ (600Ah total) in parallel

  • Skoolie conversion

  • No Cerbo GX

  • Solar array ~130V open circuit

Symptoms

  1. System repeatedly shuts down on “low battery” according to the Multiplus II, even when all battery devices (BMV, MPPT, measured at terminals) show ~13.0–13.2V.

  2. BMV SOC often shows 85–100%, but the Multiplus still trips low battery during light loads (lights, fan).

  3. When the system trips, resting battery voltage measured at the batteries is ~13.05–13.20V.

  4. Solar charger reaches Bulk → Absorption → Float normally during sunny days or when connected to shore power.

  5. After full shore-power charge (Multiplus spent hours in Absorption), the next morning the Multiplus reports low battery again, even though:

    • BMV shows ~100%

    • MPPT shows Float

    • Measured resting battery voltage is ~13.0V

  6. No major AC or DC loads running — only minimal parasitic draw.

  7. Batteries individually disconnected and tested — each one shows ~13.03–13.05V resting.

What has already been checked / done

  • Reprogrammed MPPT: changed from AGM preset to LiFePO₄ settings (Bulk/Absorption 14.4V, Float ~13.5–13.6V).

  • Reprogrammed BMV: verified battery capacity (600Ah), Peukert settings, charged voltage threshold, and re-synced after full charge.

  • Reprogrammed Multiplus to correct LiFePO₄ voltages.

  • Solar producing normal wattage depending on sun (PV ~130V, 0.1–1.2A into MPPT).

  • Batteries individually isolated and voltage-checked — no obvious dead cells.

  • All DC loads switched off (AC main breaker off).

  • No MPPT or Multiplus error codes.

  • MPPT History shows normal daily yield (~0.8–0.9 kWh on good days).

  • BMV History had a historic minimum of 0.02V (likely from a BMS cutoff event before reprogramming).

  • Multiplus charges correctly via shore power (Bulk → Absorption → Float).

  • After charging, system still enters low-battery shutdown overnight.

Core Problem

The Multiplus II is seeing a much lower voltage than both the BMV and the MPPT, causing it to hit LV Shutdown even when the battery bank is actually ~13V.

The problem appears to be:

  • Voltage drop or intermittent connection between batteries → shunt → Lynx Distributor → Multiplus OR

  • A config/firmware issue causing incorrect LV cutoff behavior OR

  • An intermittent internal BMS disconnect on one Battle Born battery dropping bus voltage momentarily.

The biggest confusion:
All Victron devices show the system fully charged, yet the Multiplus trips due to “low battery.”

Questions for the forum

  1. Has anyone seen a Multiplus II falsely tripping low-voltage while BMV/MPPT show normal voltage?

  2. Could the Lynx Distributor or a single battery BMS dropout cause a momentary voltage collapse that the Multiplus reacts to but the BMV/MPPT do not register?

  3. Is there a known firmware bug related to LV cutoff on the Multiplus II with LiFePO₄ banks?

  4. What is the best way to verify whether a single Battle Born BMS is intermittently disconnecting under load?

  5. Are there additional Multiplus parameters that may cause shutdown even when DC voltage is 13V?

What I’m looking for

Specific advice on:

  • Diagnosing intermittent voltage drop on DC side

  • Proper Multiplus II LV cutoff values for 12V LiFePO₄

  • Whether a single weak battery in a 6-parallel bank could cause this exact symptom

  • Whether I should update Multiplus firmware

  • Additional wiring/connection locations that could cause the Multiplus to see a different voltage than the BMV/MPPT

3

@kansasheadhuntr
Be careful with the AI structure of the post. Try be abit more human.
Also a shorter post would be easier to deal with here.

4

Not likely it would have to be all tripping, or some are tripping and then the others are then also due to having to carry a large load
Could be out of balance and not charged correctly. So you have one or two weak cells

Other possibility is high resistance connections on the DC connection side. What size are your DC cables etc? And pretty much all connections including bad crimps and incorrect torque can cause volt drop. Are all the cables from each battery to the lynx the same lenght?

This can be caused by DC ripple. Which points to insufficiency on dc side in cabling or connections. Other than an inverter fault in which case it should be returned for an RMA.

What settings have you actually used? Battle born have quite a few guides.

Shunt

Inverter

Yes. Components should always be updated in system commissioning or during troubleshooting. And then all components done not just one or two.

Talk some time to do some self learning using wiring unlimited.