Balancing and Charging Targets | Victron Inverter

Hi Renzee,

many thanks for your answer. This sheds a much more detailed and different light on Batrium for LiFePo4.
Now given that balancing starts at 3.55V, how would you advise to configure the float state after finishing the balancing? Let’s assume every cell is now equal at 3.55V, every cell is full and there is still a lot of PV power coming in, which now needs to be feed in into the grid instead of feeding into the battery.
My current knowledge is to keep cells fully charged at 3.37V. If I configure this - float voltage for a 16s pack is then 53.92V - the voltage drop of PV chargers from 56.8V (16 * 3.55V) to 53.92V causes now the current to float from the battery through inverters into the grid instead of floating from the PV chargers due to higher voltage in the battery for some time. This discharges the battery pack a little bit but enough to make Batrium think, we need to fall back into charge cycle. Charge voltage is not reported again as 56.8V instead of keeping 53.92V until e.g. SoC drops below maybe 95%. This cycling now remains the whole day until there is not more PV power.
Is there a possibility to configure a higher hysteresis until Batrium falls back into charging? If cells are full, I would like to keep them at a lower voltage than the charge voltage (let’s call it a float voltage) until SoC drops below something beyond 90%. Is that possible somehow to configure?

Many thanks in advance!

Edit: Today was a good day to get batteries full again and then the following happens:


Please ignore my bypass voltage reduced to 3.40V and assume it is 3.55V. But then the different between charge voltage and float voltage would be even greater.

1 Like

@kleini we moved your question to a new topic as we believe this is different from the original topic where it was first posted.

Please see response below:

We’ve been in discussion with Victron with regards to the inverter CANbus profile to understand why when the BMS advises the inverter to stop charge by setting the charge current to 0A that this works for their equipment when configured as off grid yet ignores this request when grid connected.

They have proposed enhancement to their GX that could be completed on their equipment to handle this request to stop charge.

However, we are both exploring the option of further enhancing the BMS firmware to enable voltage charge threshold adjustments when wanting to change the charging operating logic, specifically including when to stop charge and optionally throttling down the charging rate via voltage targets.

Further to this balancing targets and charging targets should not be the same values and should be staged independently.

Many thanks for your answer.
In my eyes, charging and balancing works very fine utilizing ramped charge targets. Only when the voltage drops to float Batrium thinks too early, charging is necessary again and raises CVL and CCL again.
I want to implement a workaround on my side to avoid this cycling around full and need to charge again. I will utilize Node-RED and create two flows there:

  1. First flow will listen for 100% SoC in GX device. Once this is seen, I will limit charge voltage in DVCC to float voltage, which is the same I configure as voltage in the Limited ramped charge target.
  2. Second flow will list for 95% SoC in GX device and then remove the charge voltage limit in DVCC and the configured charge voltage in Batriums ramped charge targets is again the one to be used.

This should then provide a stable charge, full, discharge and charge again cycle between 95% and 100% SoC and once batteries are fully and PV power is still available it should remain at 99% SoC.

I hope, this sounds like a good idea.

If you’re in discussion with Victron, I would like to encourage to implement the reporting of charged and discharged amphours to the Victron GX device. Victron needs this information from the battery to calculate DC consumption. I installed a mix of Victron inverters and DC step down converter and would like to know in the Victron monitoring, how much is consumed by DC consumers in my installation. Thank you very much!

3 Likes

Hello Renzee,

may I kindly ask, how it is going with the Victron integration regarding the float voltage implementation?
Is there any progress you might want to tell us?

Cheers,
luphi

1 Like