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Quattro 48/8000 230v short at DC side - new install

Hi,

I was going to upgrade the firmware of a Quattro 48/8000 (first time power on). The only cables that are connected are the DC battery cables (yes I checked polarity). Even with the quattro power switch (the 3 way rocker switch on the Quattro) in the OFF position there seems to be a short! The battery BMS turns of and reports a short. Is the quattro defective? I have a Blue Sea 300A main switch in front of the Quattro. when I tried a second time I saw it spark so there really seems to be a short :(.

Is there a way I can verify that the Quattro is the problem?

Best regards

MultiPlus Quattro Inverter Charger
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michaeld answered ·

You need a solution to pre-charge the capacitors in the inverter. The inrush current required can be extremely high and trip the BMS. That's the same reason why you're seeing sparks which will eventually damage the main switch contacts. It's nothing specific to the quattro and will happen with any large inverter. Some people use a pushbutton with a resistor to allow a small amount of current to pass, slowly charging the capacitors for a few seconds before turning on the main switch. Alternatively depending on your BMS they may have a module to do this automatically (e.g. REC-BMS sell a pre-charge module). Search for "inverter pre-charge resistor" for some more info.

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some-user answered ·

Thank you! Will try and let you know the result!

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thanar answered ·

Charge up the inverter's capacitors slowly by using a high power (over 48V rated) incandescent bulb in series while connecting the battery to the DC bus. Hold it there for 10 seconds, and then quickly connect as usual.

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nickdb answered ·

The caps will want to charge even in the off position. The easiest way, if you have solar, is to start the mppts first and then enable the battery.

Without PV and with a sensitive BMS, only a precharge circuit will do, plenty of examples on tubeyou.

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some-user answered ·

That worked like a charm. Used a 50E 100W resistor with a 54V power supply to pre-charge the capacitors (my batteries deliver 54V to the busbar). If you use a volt meter and measure the voltage over the resistor you can see the voltage drop while the capacitors get more and more charged. Once close to 54V I removed the pre-charge power supply and powered the inverter from the batteries. No issues.

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michaeld avatar image michaeld commented ·
Glad to hear it :)
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