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Multiplus 2000 Buzz and Current Draw and fans.

I have a new, out of the box Multiplus 2000, 12V on a test bench setup. Feeding it is 280AH of Lithium @ 13.5V. I start the inverter and it's quiet. I put a load on it via a heat gun and it immediately starts a loud low frequency buzz. The heat gun pulls 70Amps of from the pack measured on the BMS and a DC clamp meter, but Victron Connect shows -43 Amps. All connections are tight and double checked. Wire Gage is correct.

There is also a fan and temperature fault issue. When both fans come on during inverting or charging, they struggle to blow at full speed and emit noise (not wind noise, a fast clicking is the best way to describe it) and the Multiplus eventually goes to temperature fault then shuts down some time after the fault. Before the shutdown, I unplug one fan (top of board, Right Side Fan) and the remaining fan jumps to full speed, as normal, with no clicking sound. I plug the right fan back in and both immdiately go to clicking, slow down and appear to struggle. The fan voltage on the top connector with no load is 8V DC.

Anyone have any ideas?

MultiPlus Quattro Inverter ChargerVictronConnect
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blutow answered ·

On the heat gun noise issue - I just ran into this same thing while bench testing a new multiplus. It would create a really loud buzz when turning the heat gun to medium and it would go away when switch to high. I did a search and found something that talked about heat guns using a diode on medium heat and the inverter really doesn't like it. I unhooked the heat gun and tried applying a similar load with a halogen work light and there was no noise. I think the post about the diode was on this forum, but I am too lazy to search.

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After some extensive troubleshooting, The poster about the heat gun was probably correct. I eliminated the heat gun and switched to several different loads, and all the ailments disappeared. Now, the heat gun I was using was at least 20 years old. So, Victron wins again. I also believe the heat gun introduced weird noise on the AC line that messed with the inverter, but I don't have the test equipment to verify that.