Turing Inverter on/off from Charge Controller Victron 150/100

Been down this exact rabbit hole with my static caravan setup — controlling inverter state from the Victron MPPT rather than manually switching things.

The short answer is the Victron 150/100 doesn't have a dedicated inverter control relay output the way the SmartSolar range does with its programmable relay. What you can do is use the VE.Direct TX port on the SmartSolar variant and wire that into a relay board, then trigger the inverter's remote on/off terminal from that. Bit fiddly but it works.

If you're running a Cerbo GX or even a Venus GX as the hub, that opens up proper relay logic — you can set rules based on SOC, voltage thresholds, time-of-day, all that. My setup triggers the inverter off below 50% SOC automatically which has saved my batteries more than once.

Few things worth thinking about for a 24v 2000w system specifically:

• What inverter are you actually considering? Some have a proper remote terminal, others are just a switched live which complicates things
• Battery chemistry matters a lot here — LiFePO4 with a decent BMS changes what SOC thresholds make sense vs AGM
• Are you planning VE.Smart networking to link the MPPT and a BMV battery monitor? Makes the whole system far more intelligent

I went with a Fogstar Drift 24v setup eventually and wired everything through a Cerbo — honestly transformed how reliable the whole thing is.

Curious what inverter brand you're looking at and whether you're committed to keeping the 150/100 as the sole controller or open to adding a GX device into the mix.

@VanRhys the 150/100 won't control your inverter directly, but wire a Victron MultiPlus into the mix and suddenly your whole system's having a lovely little chat with itself via VE.Bus — proper automation without you lifting a finger (or a switch).

If you're dead set on keeping your existing inverter, a Cerbo GX with a relay output is your best mate — you can set rules like "inverter on when SOC > 50%" and it'll crack on without you babysitting it.

I've got mine set up in the van to only fire the inverter above 60% SOC, saved my Fogstar batteries from an embarrassing early retirement.

@RiverFinn makes a fair point about the MultiPlus, but there's a simpler route if you don't want to go full inverter-charger.

The 150/100 has a programmable relay output (TX port via VE.Direct) — you can configure this in VictronConnect to switch based on battery voltage or SOC thresholds. Wire that relay output to a decent contactor (Albright-style, 12/24V coil), and that contactor controls your inverter's remote on/off terminal.

Done exactly this on my narrowboat with a Renogy inverter — set the relay to open below 20% SOC and close again above 50%. Prevents the inverter dragging the bank into the floor overnight.

Only caveat: the TX relay is low-current signal only, so don't try switching the inverter's main feed directly through it. Always use a proper contactor rated for your load.

@ExSquaddie49 go on then, don't leave us hanging 😄

For what it's worth, on my static I ended up using the Victron MPPT's load output to trigger a relay, which then controls the inverter's remote on/off terminal. Dead simple, costs pennies, and the MPPT handles all the voltage logic — kicks the inverter off when the battery drops below your set threshold.

Only gotcha is your inverter actually needs a remote terminal. Cheaper units sometimes don't bother. Learned that the hard way with a no-name thing I bought off eBay at 2am (we've all been there).

Works a treat now though — Victron 100/30 running the show, Fogstar batteries, and the inverter minds its manners automatically. No more coming home to a flat pack.

@DustyCaptain the relay output on the MPPT is the key bit people miss. On the 150/100 you've got a programmable relay you can configure in VictronConnect to trigger on SOC thresholds, battery voltage, whatever suits you. Wire that relay to a decent contactor and you can have your inverter switching on/off automatically without needing a MultiPlus or any complex CAN bus nonsense.

Did exactly this on my narrowboat — relay triggers the contactor at 50% SOC off, 70% back on. Keeps the inverter from hammering the bank when it's low.

Only gotcha: the relay is low-current rated so don't wire your inverter direct to it. You need that intermediate contactor stage. Victron's own documentation is a bit vague on this but it's straightforward once you've got your head round it.

@GafferTapeKing19 is right about the relay, but worth noting the contacts are rated pretty low — 4A max if I remember correctly. On my boat I ran that relay output into a proper contactor coil rather than directly switching the inverter load or even its remote on/off terminal, just to be safe. Some inverter remote inputs draw more than you'd expect.

Also check your inverter's remote on/off logic — some want a contact closure, others want a voltage signal. Caught me out the first time. The Victron VE.Configure software lets you set the relay trigger conditions (SOC threshold, voltage, whatever suits your setup) which is where the real flexibility is.

@KevScott the 4A relay contact catching people out is basically a rite of passage — I fried a cheap relay module learning that lesson on my van build, now I run a proper Victron Battery Protect as the intermediary and sleep like a baby 🔌💤

@VoltMax burnt offering to the solar gods aside, worth adding that if you've got a Cerbo GX in the mix you can skip the relay faff entirely and use the virtual switch or even Node-RED to toggle the inverter based on SOC — my garden office setup does exactly this and it's suspiciously reliable, which frankly makes me nervous.

@RockyMender raises a good point about the Cerbo GX — worth expanding on that slightly. With a Cerbo in the system you can set up Generator Start/Stop logic or use Node-RED (via Venus OS Large) to trigger the inverter based on SOC, time-of-day, or PV yield thresholds. Far more granular than the MPPT relay alone.

In my tiny house setup I'm running exactly this — Multiplus 2 controlled via Cerbo using a Node-RED flow that only enables the inverter above 30% SOC. Prevents the Fogstar cells seeing repeated low-voltage stress.

If Cerbo isn't in the budget, the relay-plus-intermediate-relay route others have described is perfectly solid.

@LDVConvert good breakdown on the Cerbo GX path. One thing worth adding for anyone going the relay route without a GX unit — the Victron 150/100's programmable relay can be set to trigger on battery voltage thresholds via VictronConnect, so you can make inverter on/off decisions autonomously without any extra hardware. Set it to close at say 26.4V and open at 24V, wire that to a proper intermediate relay (coil-rated, not direct load switching), and you've essentially got automatic load shedding. My cabin setup runs exactly this — keeps the inverter off during cloudy spells without me babysitting it. 🔋

@DailySolar solid point on the relay protection. One thing I'd add — if you're wiring the load output relay to trigger your inverter's remote on/off terminal, double-check the inverter's input voltage requirements first. Some cheaper units want 12V on that pin, others want a dry contact closure. Got caught out with this on my van build; the Victron relay output wasn't what the inverter expected. Quick fix was a small relay board in between. Worth 10 minutes with a multimeter before you commit any wiring.