Quattro and Skylla-TG in parallel

Running a Quattro alongside a Skylla-TG charger on the same lithium bank is something I've been mulling over for my motorhome conversion, so this topic is very timely.

My current setup uses a Victron Quattro 12/5000 with a 280Ah Fogstar Drift LiFePO4 bank managed by a Cerbo GX. Works beautifully on its own, but I'm considering adding a Skylla-TG 24/100 for those times when I'm on a decent hookup and want more aggressive bulk charging without hammering the inverter/charger unnecessarily.

The bit that concerns me is charge source coordination. When both units are active simultaneously on a shared bank, you really need them playing nicely together — ideally both talking to the same BMS via DVCC on the VE.Bus network. The Skylla-TG does support VE.Can, which helps, but the voltage and current limits need to be handed down correctly from the BMS to both chargers, not just the Quattro.

Has anyone actually run this combination with a Lynx-style BMS or even just a smart BMS with CANbus output? I'd specifically want to know:

• Whether DVCC properly governs the Skylla-TG's charge current in practice, or whether it sometimes ignores the CVL/CCL signals
• Whether there are any known firmware quirks when both units try to absorb simultaneously

I've seen a couple of Victron community threads suggesting the Skylla-TG can occasionally "go rogue" on its absorption voltage if it's not on the latest firmware, which would be a concern with lithium.

Anyone running this combination in a land-based off-grid setup or a vehicle? Genu

@Curly the key thing to nail down before anything else is whether your BMS can handle charge current from two sources simultaneously without getting confused about the total current flowing in/out.

With a Quattro and Skylla-TG both active, you could easily saturate a bank that looks fine on paper. The Skylla doesn't communicate over VE.Bus, so the Quattro has no visibility of what it's pushing in.

Practical fix: DVCC on a Cerbo GX will let you set a system-wide charge current limit, and the Skylla-TG does support that via VE.Can. That's how I coordinate charging on my static caravan setup — everything talks back to the Cerbo and nobody goes rogue.

What BMS are you running? That'll determine whether you've got hard overcurrent protection or whether you're relying purely on the charge parameters being set correctly.

@BayJason makes a solid point about the BMS — worth adding that the Skylla-TG and Quattro can both be set to charge profiles independently, which is where people get caught out. If your BMS triggers a high-voltage disconnect, neither unit "knows" the other was already pushing current.

On my boat I run a Quattro 24/3000 and had similar concerns before settling on a dedicated BMS with two separate charge-enable outputs. Lets me curtail each charger independently if needed.

For the motorhome use case, also worth checking whether the Skylla-TG firmware supports the Victron VE.Can network — if both units can talk to a Cerbo GX you get much cleaner coordination between them rather than flying blind.

@VoltChloe that's a good shout on the charge profiles — but has anyone actually tested what happens when both units are active simultaneously and the BMS triggers a charge disconnect? Does the Quattro handle the sudden current interruption gracefully, or does it throw faults?

I'm genuinely curious because I've got a Fogstar Drift 200Ah and the BMS can be a bit "decisive" when it cuts off 😅

Also wondering whether you'd use the Quattro's assistant framework to coordinate with the Skylla-TG, or just rely on matching the voltage/current settings manually and hoping they play nicely together? Is there a two-wire BMS assistant setup that covers both simultaneously, or does each unit need its own signal?

@Curly what BMS are you planning to run with this? That feels like the crux of the whole thing really.

@Cleggy that's exactly what I'd want to know too! I've got a Quattro on my static caravan paired with a Fogstar Drift lithium bank and I've often wondered what happens when two charge sources "disagree" with each other — does one back off, or do they just both pile in regardless?

Specifically, is there any DVCC magic happening over VE.Bus/VE.Can that coordinates the two units, or are they essentially operating blind to each other? I know Victron's ecosystem is supposed to talk to itself, but I'm not sure the Skylla-TG plays nicely in that conversation — is it even on the same bus?

Anyone actually checked this with a proper current clamp to see how the load splits in practice?

@OldSparky curious what your Fogstar Drift is doing when both units try to charge simultaneously — that's the crux of it really.

From my cabin setup, I found the key is letting the BMS be the single source of truth. If your BMS can send a DVCC signal via VE.Bus or CAN, the Quattro will respect it and the Skylla-TG can be slaved down manually. Without that coordination you're essentially two chargers arguing over the same bank.

Victron's own docs suggest keeping one unit as "master" for absorption cutoff. In practice I'd lean on the Quattro for that and set the Skylla a shade lower on voltage so it naturally backs off first.