Why does the system still manipulate the different power flows when Dess is off?

So I've been scratching my head over something that happened last week during that absolutely miserable stretch of grey skies we had (classic British summer, cheers for that).

My Victron-based van setup has been doing something I can't quite explain. I switched off DESS because the forecast was being wildly optimistic about solar generation — honestly it thought I was parked in the Sahara rather than a layby in the Lake District — and I didn't want it making daft decisions based on bad predictions.

What I expected: system just sits there, holds its horses, no clever routing of power, minimal intervention.

What actually happened: it's still shuffling power around between my Fogstar lithium bank, the shore power hookup, and the EV charging side of things. Like it's still thinking about something, even though I've told it to stop thinking.

A few specific questions:

• Is DESS only controlling the scheduling/forecasting layer, or does it also govern lower-level power flow logic?
• Could this be ESS mode doing its own thing independently of DESS being enabled?
• Is there a way to actually put the system into a proper "just do the basics, nothing clever" mode without disabling ESS entirely?

I had a dig through the Victron community docs but got lost somewhere around page 47 of a PDF that clearly wasn't written for humans.

Has anyone else noticed their system continuing to manage flows after switching DESS off, particularly during low-generation periods with variable grid tariffs? Would love to know if this is expected behaviour or if something's misconfigured on my end.

OddJobBob79 | 47 posts | Midlands

@PeakCamper Looks like your post got cut off mate, but I think I can guess where you're heading! Classic one this.

The short answer is that your Multiplus (or Quattro?) doesn't need Dess running to manage power flows - that's all happening at the firmware level on the inverter/charger itself. Dess (VRM/Venus OS) is essentially just the monitoring and remote control layer sitting on top.

Your MPPT, battery BMS and Multiplus are all chatting away to each other via VE.Can or VE.Direct regardless. The GX device just observes and logs it.

Finish your post and we'll give you a more specific answer - would be useful to know your exact setup too. What batteries are you running?

Renogy_Pro | 1,247 posts | Array

@PeakCamper Your post did get cut off but I'll take a punt at what you're seeing — the MPPT, inverter/charger, and DC loads are all still negotiating with each other via the shared busbar regardless of what DVCC or ESS is doing in software. The hardware doesn't care about your settings; Ohm's Law is stubbornly indifferent to your menu configurations.

Victron kit in particular will still prioritise battery protection thresholds, absorption cycles, and load shedding at the component level even if ESS is completely disabled. Your BMV or SmartShunt is still feeding data around via VE.Direct.

Finish your original post though — "van se..." could mean about fifteen different things and I'd rather not spend three paragraphs diagnosing the wrong problem. What's your actual battery bank? Fogstar Drift cells behave quite differently from a stock AGM setup in these scenarios.

EssexCruiser | 203 posts | Array

@PeakCamper your post got cut off harder than my solar yield last Tuesday — but DVCC keeps doing its little power-flow puppet show regardless of whether DESS is enabled, because DVCC is the actual conductor of the orchestra and DESS is just the bloke who requests which song gets played next.

LiamFrost70 | 312 posts | Array

@PeakCamper post definitely truncated, but worth adding something the others haven't touched on yet — even with DESS (Dynamic ESS) completely disabled, the Victron GX device never truly goes passive. The MPPT, inverter/charger, and BMS are still exchanging data over VE.Can or VE.Direct and the GX is continuously arbitrating between them according to its base charge algorithm.

DESS is essentially a scheduling layer on top of that existing framework — strip it away and the underlying load-balancing logic remains fully intact. Your system didn't go rogue; it behaved exactly as designed.

Running a similar Victron setup in my shepherd's hut and witnessed identical behaviour during a grim overcast fortnight — batteries self-managed sensibly without DESS doing anything. Check your ESS mode settings in the GX console before assuming something's misbehaving.