Managing Victron Over Voltage Alarms with DVCC
Managing Over-Voltage Alarms During Battery Balancing Using Victron DVCC Voltage Control
When running lithium batteries with internal BMS balancing — such as SOK or other LiFePO₄ modules — it’s common to see momentary high-voltage alarms during the final stage of charging. This typically happens when one or more cells reach their upper limit before others, causing the BMS to begin balancing while the charger or inverter is still pushing current. The result is a pack-level voltage spike that can trip Victron’s over-voltage alarms or trigger premature charge termination.
Understanding the Cause
Balancing occurs when the battery is nearly full (typically above 3.4–3.45 V per cell). Individual cells within the pack can rise faster than others, and the BMS will bleed or bypass current on those cells to bring them back in line. However, the charger only “sees” total pack voltage — not the individual cells — so it can briefly overshoot the overall target voltage before the BMS finishes its work.
If the Victron inverter/charger or MPPT sees this as an over-voltage event, it may:
- Stop charging prematurely
- Generate repeated “High DC voltage” warnings on VRM
- Disconnect the solar input or inverter output temporarily
The Role of DVCC (Distributed Voltage and Current Control)
Victron’s DVCC system allows a GX device (such as a Cerbo GX, Venus GX, or Color Control GX) to coordinate voltage and current set-points across all charging devices. When enabled, DVCC ensures that all connected chargers — solar, inverter/chargers, and others — follow a single system-wide charge reference.
This is particularly valuable when you need to limit or slightly reduce the maximum charge voltage during the balancing phase.
When Using Battery-to-Inverter Communication
Suppose your system uses battery-to-inverter communication (for example, via a CAN-bus connected SOK or Pylontech battery). In that case, the BMS will automatically broadcast its own charge-voltage and current limits to the GX device. In most cases, DVCC will respect these limits and override any manual settings.
However, during balancing — especially when cell voltages rise unevenly — it can be helpful to apply a DVCC voltage limit to keep the charging voltage just below the BMS high-cell cut-off threshold. The GX device’s “Maximum charge voltage” setting acts as a cap even when the BMS is communicating, ensuring the overall system does not push the pack too aggressively at the top end. This allows the BMS to balance more gently without triggering alarms or charge cut-offs.
How to Apply a Voltage Restriction
- Access the GX Device
Log in to your Cerbo GX or other GX device via Remote Console (local display or VRM). - Enable DVCC
Go to:
Settings → System Setup → DVCC
Ensure DVCC and Shared Voltage Sense (SVS) are both enabled. - Set a Temporary Charge-Voltage Limit
In the DVCC menu, manually enter a “Charge Voltage Limit.”
For example, if your lithium battery manufacturer specifies 14.6 V (for 12 V systems), you might temporarily reduce this to 14.2–14.3 V during balancing.
This reduction:
- Keeps the pack below the BMS’s high-cell trip point
- Allows the balancing process to complete cleanly
- Reduces nuisance over-voltage alarms
- Monitor and Adjust Gradually
Watch cell voltages through your BMS app or battery monitor. Once the cell-to-cell difference drops below ~10 mV, slowly increase the charge voltage back toward the manufacturer’s nominal setting—usually in 0.1 V steps.
If alarms reappear or a cell rises too fast, reduce the voltage again and allow more time for the BMS to equalise the pack before attempting another increase.
Incremental adjustments prevent overshoot and allow balancing to be completed under controlled conditions.
Recommended Practice
- For SOK 12 V batteries, balancing typically occurs around 14.2–14.4 V. Start low and step upward once the cells stabilise.
- For 24 V and 48 V systems, scale proportionally (×2 or ×4).
- With CAN-connected batteries, DVCC’s manual limit acts as a protective ceiling rather than an override — the BMS’s lower limit will always take priority.
Benefits
- Prevents false over-voltage alarms and charging interruptions
- Reduces BMS stress and prolongs cell life
- Provides safe voltage capping even when battery communications are active
- Keeps multi-charger systems (solar, grid, and generator) synchronised under one voltage reference
In summary:
When lithium batteries are balancing, DVCC’s voltage limit on the GX device acts as a smart safety cap — even when battery-to-inverter communications are active. By temporarily lowering the limit, then slowly raising it as balance improves, and reducing it again if alarms return, you can achieve a clean, stable top-balance without nuisance shutdowns or alarms.