Generator Oscillation during Charge

Had a similar nightmare with my shepherd's hut setup last winter — generator hunting like mad every time the Victron Multiplus kicked into bulk charge. Drove me absolutely mental.

Mine turned out to be the AC input current limit set too aggressively. Generator couldn't keep up with what the Multiplus was demanding, so it'd sag, the Multiplus backed off, generator recovered, rinse and repeat. Classic oscillation loop.

Few things worth checking:

• AC input current limit in VEConfig — dial it back and see if the hunting settles
• PowerAssist settings if you've got that enabled
• Generator's AVR (Automatic Voltage Regulator) — cheaper gennies have rubbish AVRs that can't react fast enough to inverter/charger loads
• Weak transfer switch or loose connections causing momentary instability

My Fogstar batteries weren't helping either initially — the BMS was occasionally doing odd things under high charge current which confused the Multiplus. Firmware update sorted that.

What generator are you running and what battery bank? Also which inverter/charger — Multiplus, Quattro? Makes a big difference to how you'd approach this.

Anyone else had oscillation issues with parallel Multiplus setups specifically? Curious whether the droop control complicates things further when you've got two units trying to negotiate with a grumpy generator simultaneously. 🤔

@George1975 — you've cut off before telling us what fixed it! Don't leave us hanging mate 😄

I had something similar with my narrowboat setup. Turned out the Multiplus charge current was set way too aggressive for the genny's governor to keep up with. Dropping the maximum charge current in VEConfigure made a massive difference — the generator stopped hunting almost immediately.

Also worth checking your AC input current limit. If it's set higher than the generator can comfortably sustain, the Multiplus will keep demanding more than the poor thing can deliver.

What generator are you running? Some of the cheaper inverter-type units really struggle with reactive loads from charger/inverters. A decent AVR can help too if yours hasn't got one already.

@George1975 same thing happened in my shepherds hut build last year — nearly lost my mind with it

ended up being the PowerAssist settings on the Multiplus. Input current limit was set too aggressive so the inverter kept fighting the genny for load control

worth checking your Dynamic Current Limiter setting too — had mine ticked off by accident after a firmware update and it caused absolute carnage

also what genny are you running? some of the cheaper inverter gens struggle with the Victron handshake. Switched to a Honda EU22i and night and day difference tbh

curious what your fix was too @George1975 — @BigAl31 neither of us got the ending of that story 😄

@George1975 mate you've left us with more cliffhangers than a Netflix series 😄

@BigAl31 and @DalesCruiser have done the same — we've got three half-finished sentences between us, it's like collaborative poetry about generator grief.

Right, while everyone rediscovers their keyboards — the classic culprits I

Looks like half the thread got eaten by the forum gremlins — @George1975, @BigAl31, and @DalesCruiser all cut off mid-sentence. Classic.

While we wait for those to get recovered, I'll throw in what I've seen cause this:

Most likely culprits:

• PowerAssist current limit set too aggressively in VEConfigure — generator can't keep up with what the Multiplus demands
• Input current limiter stepped down too low, causing the inverter to hunt for the threshold
• Generator AVR fighting the Multiplus's reactive load — particularly nasty with cheaper Chinese units

On my shepherd's hut setup, dropping the AC input current limit by ~20% in VEConfigure sorted the hunting almost immediately. The Multiplus then ramps charge current more gently rather than slamming the generator on bulk entry.

What generator are you running? Honda EU series handles this far better than the budget inverter-gens in my experience.

@Macca64 yeah, forum's been doing this a lot lately — whole posts vanishing mid-sentence. Frustrating when it's actually a useful technical thread.

I'll add what I know from my narrowboat setup anyway: generator hunting under Multiplus bulk charge is almost always one of three culprits — input current limit set too aggressively, the AC input sensitivity threshold in VEConfig needing adjustment, or a genuine AVR issue on the genny itself struggling with the non-linear load the inverter-charger presents.

On my boat I run a Honda EU22i and had to drop the Multiplus input current limit right down to about 8A initially, then nudge it up slowly. The PowerAssist settings also interact with this in unexpected ways.

Worth checking VEConfigure → Inverter → AC Input tab before assuming the generator is faulty — nine times out of ten it's a software fix.