question

carel-landman avatar image

Is my MPPT Output Power limited by my BlueNova battery?

Good day

I have a question regarding a system I recently commissioned. The system consists out of the following:

  • Venus GX – Firmware version v2.63
  • MultiPlus 48/5000/70-100 – Firmware version 475
  • BlueNova BN52V-100-52k Du - Firmware version v1.9
  • SmartSolar MPPT VE.Can 250/100 rev2 - Firmware version v3.02
  • 15 x 325W JA Solar PV panels
  • Energy Meter ET112

The maximum charge current that the BlueNova battery can handle, is 50A (Discharge current of 100A). I noticed that the output power of the MPPT is limited to about 2700W, which equals a battery current of 50A, see the screenshots below. Is it so that the MPPT will not produce more than 50A in this case, even if the battery is fully charged and feedback is enabled? I.E. the MPPT is throttled to the maximum charge current the battery can handle? I could not find any documentation regarding Battery Charge Current when sizing a MPPT, did I maybe overlook it? Any suggestions would be appreciated.

11.png22.png33.png44.png

Kind Regards

MPPT - Solar Charge Controller
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4 Answers
carel-landman avatar image
carel-landman answered ·

The problem has been solved as follows:

If you connect directly to the MPPT by using Bluetooth and the VictronConnect app, you should set the battery current to the maximum that the MPPT can output. This needs to be done, although the MPPT is supposed to be externally controlled, to ensure the MPPT can output the rated power. I can also confirm that setting the MPPT charge current to the maximum value, does not clash with the maximum charge current that the battery can handle. The GX device and the BMS manages the amount of current that is used to charge the battery, thus there is no alarm present and the battery is not getting damaged. The excess MPPT power is fed back into the grid and the MPPT is no longer throttled.


Credit to @Seb71 for pointing out that this information can be found within the Cerbo GX manual, https://www.victronenergy.com/media/pg/Cerbo_GX/en/introduction.html, see 8.4.1.


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That was explained in the manuals I linked to you two days ago.

And I kept telling you to read them.

Hi Seb


In the manuals you linked, I could only find the following under MPPT settings: 1614663356601.png

But as I confirmed on site, the MPPT charge current also has to be set to the maximum value it can produce. Not sure if we are misunderstanding each other, if so, I apologize.

1614663356601.png (6.5 KiB)
seb71 avatar image seb71 carel-landman ·

In the DVCC section of the Cerbo GX manual, which I linked, you can read this:


8.4.1. Limit charge current


[...]


5) In all situations, the maximum charge limit configured in a device itself, ie. the Charge current limit set with VictronConnect or VEConfigure for the Solar chargers or Inverter/chargers will still be in effect. An example to illustrate this: in case there is only an Inverter/charger in the system, and in VEConfigure or VictronConnect the charge current is configured to 50 Amps. And on the GX Device, a limit of 100A is configured, then the working limit will be 50 Amps.

Thanks a lot Seb!

marc-de-montreal avatar image
marc-de-montreal answered ·

hi, the mppt 250/100 with 48vbatt give 48v x 100amp = 4800watts possible.. the issue look your 50amp limit current = 2400w at 48v.. or 2658w at your screen shot values to respect your mppt batt current..

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Thank you Marc! I realize the MPPT is throttled at 50A, thus my question is if it is due to the maximum charge current the battery can handle? Do you perhaps have a workaround to this problem?

seb71 avatar image seb71 carel-landman ·

From your screenshot it seems that the 50A limit is set by the battery BMS.

I also think that is the case, so the only solution would be to add another battery?


seb71 avatar image seb71 carel-landman ·

On certain systems this desired result can be obtained by changing some settings (mainly by using DVCC). But I can't tell if it is possible for your system.


Edit

Maybe it works on your system

Read about DVCC here.

Victron battery compatibilty manual.

Victron Energy and BlueNova Energy LiFePO4 Batteries.

Thank you so much for your reply! I have tried playing around with the DVCC settings, and even disabling it completely, without any luck.


seb71 avatar image seb71 carel-landman ·

If this is to work, you want DVCC enabled, not disabled.

Read the links I gave you.

It is and was enabled, that is why I tried disabling it to see if it makes a difference.

seb71 avatar image seb71 carel-landman ·

You don't just enable DVCC. Read those links first.

I have read those, as we have several other BlueNova batteries installed. See the screenshot below for reference:

1614169654303.png

1614169654303.png (6.7 KiB)
marc-de-montreal avatar image
marc-de-montreal answered ·

in respect of your batteries charging limit capacity, the only way i figure is to have more batteries capacity for to have more power from your solar array.. your setting is good for your actual batteries bank.. the 50amp limit protect your batteries and during the cloudy days, you still have power by your oversized solar panels!!

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Thank you Marc, I also thought that the only workaround would be adding another battery. I was just hoping there would be another way!

Murray van Graan avatar image
Murray van Graan answered ·

Hi @Carel Landman. Even with DVCC enabled, the Pv should be able to supply the 50A to the battery, and whatever else it can give to the load and grid above that. One way to isolate this is to disconnect the CanBus comms between battery and GX device (provided you have programmed the recommended charge voltages in both the multi and MPPT), and see what happens. If the PV yield does increase after that, you’ve detected a bug...

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Thank you for this answer, Murray. I have solved the problem, I will post the answer in a separate comment below!