MultiPlus does not accept mains or generator input

Check the AC input protection and the source itself: the breaker or fuse before the device, power at the hook-up post, the cable and the plugs. According to the troubleshooting table, the breaker or fuse on the AC input may trip because of overload or a short circuit on AC-out-1 or AC-out-2.

MultiPlus-II synchronises with the AC input only when the voltage and frequency are within the set range:

• Input voltage range — adjustable lower limit 180–230 V (factory setting 180 V), upper limit 230–270 V.
• Frequency range — 50 Hz, 60 Hz or 45–65 Hz (factory setting 45–65 Hz).

Measure the source voltage and frequency under load. With a long extension lead at a campsite or a weak hook-up, the voltage may drop below the lower limit.

The manual describes four settings that help with generators:

• UPS function (enabled by default) — the voltage from some small generators is too unstable and distorted, and MultiPlus-II then switches to inverter operation repeatedly. Manufacturer’s recommendation: switch off the UPS function if the device does not synchronise with the generator or keeps switching back to inverter mode. Switching to inverter mode then takes a little longer, but this does not affect most devices.
• Dynamic current limiter — for inverter generators that slow down at low load. MultiPlus-II then starts with a low draw from the generator and gradually increases it to the set limit, giving the engine time to speed up. It is also used with conventional generators that respond slowly to load changes.
• WeakAC — with heavily distorted voltage, the charger may charge very little or not at all. When WeakAC is enabled, the charger also accepts distorted voltage, but the maximum charge current drops by about 20%. The manufacturer notes that this need is rare, and recommends enabling the dynamic current limiter at the same time, and if necessary reducing the charge current so as not to overload the generator.
• Lower voltage limit for generators with AVR — the factory setting of 180 V can cause the system to shut down with synchronous generators with an AVR regulator (that is most generators from 10 kVA up). This happens when the generator is stopping, while the AVR is trying to maintain 230 V at falling speed. Solution: raise the lower limit to 220 V or disconnect the inverter from the generator with an AC contactor before the generator receives the stop signal.

In systems with inverter priority (the so-called “Ignore AC input”, off-grid mode), the device deliberately does not connect to the mains, even though it is available — this is expected configuration behaviour, not a fault. If the installer configured the system, ask whether such a function is set (for example via an Assistant or Virtual Switch in VEConfigure) and under what conditions the device should return to mains operation.

• Selected grid code: before each connection to the grid, the device tests the relays. A failed test is error 11, and if the test does not pass for more than 5 minutes (Quattro-II) — error 128. A common cause of error 11 is incorrect installation, for example swapped L and N on the input, or a neutral-to-ground connection on the output side.
• Ground relay: test during transfer to grid — error 8.
• Transfer protection: current through the transfer relay, which should be open — error 24. With generators, raising the lower input voltage limit, for example to 210 V, often helps.

• Input current limit = 0 A — according to the GX manual, the system then operates in passthrough mode with the charger switched off.
• PowerControl — when the loads draw as much as the set input current limit, the charge current drops to 0 A (the “mains on” LED flashes). Reduce the load or — if the hook-up allows it — raise the limit.
• Blown battery fuse — replace it (and find the cause).
• Bulk protection — the bulk stage lasted longer than 10 hours (the “bulk” LED flashes, the “mains on” LED is lit). Such long charging may indicate a fault, for example a shorted battery cell. Check the batteries; the mode is cleared by switching the device off and on again.
• Distorted generator voltage — see WeakAC in step 3.
• Lithium battery with BMS — the BMS may have blocked charging; see BMS has cut off charging.