Problem setting ChargeVoltage eg. current/SoC on Multiplus with MPPT450/100

Had a similar head-scratcher with my static caravan setup a while back. Running a Victron Multiplus-II alongside an MPPT 150/35 and a DIY LiFePO4 pack with a JK BMS, and I wanted to dial back the charge current — particularly during the winter months when I'm just trying to top-keep rather than do full cycles.

The issue I kept bumping into was that the Multiplus and MPPT weren't really "talking" to each other in any meaningful way about current limits specifically. You can set charge voltages easily enough in VEConfigure or via VRM, but getting granular control over current at specific SoC thresholds felt like it needed a proper automation layer.

What eventually worked for me was using Node-RED on Venus OS (running on a Raspberry Pi with Victron OS flashed). I set up a flow that reads SoC from the BMS via the GX device and then writes to com.victronenergy.settings to adjust the charge current dynamically. Bit fiddly to get right but once it's running it's solid.

For anyone with multiple MPPTs and several Multiplus units synchronised together, I imagine the complexity ramps up considerably — especially keeping charge voltage and current consistent across all devices without one overriding another.

Has anyone here used DVCC (Distributed Voltage and Current Control) to handle this more elegantly? I've read it should let the BMS take the wheel on current limits but my experience with JK BMS integration has been a bit hit and miss depending on firmware versions.

Curious what others have managed with more complex multi-unit setups.

@OldSparky18 the JK BMS is doing exactly what it should — when it wants to throttle charge current it pulls the DVCC charge voltage down via the VE.Bus/VE.Direct comms, which makes the Multiplus and MPPT both back off simultaneously. It's not a bug, it's the system working as designed.

Key thing to check: in VictronConnect → your MPPT → charger settings, make sure "Use DVCC" is actually enabled on the Cerbo/Venus OS side under Settings → DVCC → SVS/SCS/STS. If Shared Current Sense is off, the BMS can't properly signal current limits across both charge sources.

Also worth confirming your JK BMS firmware is current — older versions had quirky charge voltage reporting that confused Venus OS into thinking absorption was done prematurely. Caught me out badly last winter when my SOC readings went completely doolally during a cold snap.

@OldSparky18 this is something I battled with on the narrowboat for an embarrassing number of weeks before it clicked. The JK is essentially whispering to your Victron system via DVCC — "ease off a bit" — and the Multiplus obeys. What caught me out was assuming the voltage figure I set was the voltage I'd actually get at any given moment. It isn't. Think of the CVL (charge voltage limit) as a ceiling that the BMS can dynamically lower whenever it sees cells getting uncomfortable. Check your VRM portal if you've got one connected — watching the CVL trace over time was the moment everything finally made sense for me. The voltage bouncing around isn't a fault, it's the system working exactly as designed.

@OldSparky18 worth noting that with DVCC enabled on the Cerbo/Venus, the CVL (Charge Voltage Limit) and CCL (Charge Current Limit) signals broadcast by the JK BMS via the BMS CAN or VE.Can connection take absolute priority over whatever absorption voltage you've set in VictronConnect. So if your BMS is pushing a reduced CVL — say 54.4V on a 16S pack instead of your expected 58.4V — the Multiplus will obediently clamp there regardless. Check the BMS parameters in VictronConnect under the DVCC overview page; the live telemetry will show exactly what limits are being transmitted. On my motorhome build I had the JK cell overvoltage protection set too conservatively at the factory defaults, which caused the BMS to broadcast a throttled CVL well before the pack was full. Adjusting the per-cell limits in the JK app sorted it immediately.

Great summary from @Liam1990 on CVL/CCL. One thing worth adding — if you're seeing the charge voltage drop lower than expected even when the BMS isn't actively throttling, double-check your DVCC "Limit charge current" setting in the Cerbo/Venus GX menu. It's easy to accidentally leave a manual cap in there from testing that then overrides everything upstream. Also worth verifying your JK BMS firmware is reasonably current — older versions had some quirks around how aggressively they'd pull the CCL down during balancing, which could look like a configuration problem when it was actually the BMS being overly cautious. The VictronConnect app makes it straightforward to log what CVL/CCL values are actually being published to the DVCC bus in real time, which takes a lot of the guesswork out.