Quattro 48/10000 showing wrong voltage

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zricha asked Jan 7, '24

Quattro 48/10000 showing wrong voltage

Hi,

Following is my system setup:

- Cerbo GX version 2.9.1

- Quattro 48/10000/140-2x100 with FW version 2653508

- BlueSolar Charger MPPT 150/85 VE.CAN with screen and buttons version 2.05

Quattro is connected to the cerbo via VE BUS and MPPT charger is connected via CAN.

I noticed that the voltage read by the Quattro is always lower than the real value that is read by the Charge controller or the value read using a multimeter at the batteries poles (or the value read at the inverter batteries connectors). Following are some screenshots illustrating the case:

Photo of the voltage showing on the MPPT charge controller:

Photo of the voltage read by the Quattro:

The value on Quattro is 49.36V whereas it is actually 49.76 V.

Can you please help me identify the problem and how to resolve it?

I tried using the v-sense connected to the batteries poles without luck.

Regards, zricha

voltage quattro 10kva

whatsapp-image-2024-01-07-at-223115.jpeg (42.9 KiB)

whatsapp-image-2024-01-07-at-223122.jpeg (43.3 KiB)

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Answer 1 · 2024-01-08T05:22:40Z

Alexandra answered · Jan 08 at 05:22 AM

You have a slight voltage drop on the inverter.of 0.4v but it is feeding a load. Try measuring again with no load on the inverter.

If the voltage is dropping between the battery and the inverter, then the cable resistance is high and either terminal torque is an issue or cable gauge, lugs or connections have added resistance. If there is any kind of ripple voltage it will make the reading inaccurate. That is why ripple readings are important and are included in ve config.

The mppt is reading its own terminals. There is currently no amperage moving so should be fairly accurate.

It is also not unusual for 0.2v 0r 0.3v difference between meter readings.

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zricha commented · Jan 08 at 11:15 AM

Hi @Alexandra, thank you for your feedback.

In fact, this voltage difference is always available even during day time where the charge controller is charging and very small load on the inverter. There is no voltage drop between the inverter and the batteries; I am using 70mm battery cables and the value read at the inverter terminal is the same value read at the battery terminal (As I mentioned in my initial comment). Probably inside the inverter is making this voltage drop.

In order to compensate this voltage, I did decreased the Bulk, float and absorption voltages of the Quattro by 0,4volt in order for the charge controller to work properly. But this is not the perfect solution.

I tried using the v-sense but unfortunately, no changes. Do you know how can we force the inverter to consider the v-sense voltage instead of its internal reading?

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Alexandra ♦ zricha commented · Jan 08 at 11:29 AM

I would add a shunt.

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zricha Alexandra ♦ commented · Jan 08 at 12:38 PM

I tried it without luck. I also enabled DVCC and enabled the "SVS-Shared Voltage Sense" but still no effect.

Please help!

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Alexandra ♦ zricha commented · Jan 08 at 02:18 PM

The voltage by the quattro should not matter if the BMV is set as the battery monitor.

The system will use that voltage.

How else is the system programmed?

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zricha Alexandra ♦ commented · Jan 08 at 08:12 PM

I don't have a BMV. I rely on the inverter read voltage, and that is not an accurate value!! That is why I was trying to use the vsense.

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Alexandra ♦ zricha commented · Jan 09 at 06:13 PM

What size cable is on the inverter from the battery?

Where is the mppt connected?

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zricha Alexandra ♦ commented · Jan 10 at 12:09 AM

Cables from quattro to batteries are 70 mm2 and 1.3m long.

Cables from the charge controller to batteries is 35mm2 and 1.12m long.

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Alexandra ♦ zricha commented · Jan 10 at 05:28 AM

Can you confirm which quattro you have the I

or II? If it is the II I would imagine it needs 2x70mm cables to the battery, since the quattro II 5kva uses 1x70mm² cable. If it is the older quattro then 95mm² cable.

Have you stacked lugs on the battery terminal?

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zricha Alexandra ♦ commented · Jan 10 at 10:51 PM

This is old Quattro. The Quattro I.

Reading using the multimeter on both End of the cables confirms that there is no voltage drop at all.

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