September 27, 20223 yr Hi I am getting stumped by a Must inverter PV18-3024VPK (3kW 24V). It works fine as a UPS, but: - after a loadshed event, my load switches nicely back to utility supply and the display shows the battery being recharged. But my ammeter tells me the battery is not being charged. If I switch off the load, then the charging begins. And the charging will continue if load is switched on and off after that. Weird - the utility AC charger can be set either 20 or 30 Amp, but irrespective of the setting, my ammeter shows a very exact 10 Amp only. It is the first time that I have tried a setup on Axpert / Must / clones, so I am hoping it is only finger problems from my side. Hopefully a forum member can give some hints. Alternatively is there somebody in the Cape Town area that I can pay to do the setup? The whole system is still portable in the back of car. Thank you (The user manual is attached - all settings been put back to default for now) User-Manual-PV18-3-5KW-VHM-off-grid-MPPT.pdf
September 27, 20223 yr Author I found the problem - not finger trouble 😁 The inverter reads the battery voltage 0.3 to 0.4V higher than what all my voltmeters and the smart BMS reports. I had set float voltage to 27.0V and the battery voltage was 26.8. However the inverter was throttling the current back. For a test, I set float same as bulk at 28V and then 28 Amps was measured going to the battery. I don't know if it is worthwhile taking the inverter back because of this error - I can just offset the settings by 0.35V. The other problem of charging not starting while under load with utility supply, is my impatience. It takes about 30 seconds for the charger to come in under these conditions.
September 27, 20223 yr Just fyi, what you are describing sounds like it could be a symptom of the premature float bug that affects the 24V 3kw axperts and probably clones too. This bug causes the inverter to never actually reach the bulk voltage, it just goes straight to float when it reaches the float voltage. Might be worth testing to see if that is the case.
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