I was following the recent YouTube video to setup the Dynanic Voltages (I have a victron system). I have upgraded my software to 2.17.55 with the applicable firmware. All good so far.
For reference, I have a 21P Nissan Leaf powerwall - 48v and a WM5. I have set the LION Long Life Defaults.
I followed the video up until the point where I was changing my REMOTE CHARGE TARGETS to DYNAMIC VOLT TARGETS.
When I select this and hit the Edit and then DEFAULTS button, I can see the offset goto 0.3 and the MIN voltage goto 47.6, however when I hit SAVE these values change! The offset goes from 0.3 to 0 and the min voltage goes from 47.6 → 47.0
After doing this, my powerwall wont charge as the remote target voltage goes to 53.2v - which is my actual current pack voltage. The offset needs to be set - But I cant set it!?
I have recorded a video to demonstrate this behavior… Dropbox
I have the same issue, that I am not able to enter 0.3V and 0.1V into the Dynamic Volt Offset fields. I is always displayed as 0V. Maybe internally correct values are stored but this was too risky for me.
I think a workaround is described in this wiki, see section “How to do”, step 2: Press Default first, then Save, then change your values. Worked for me.
I tried the workaround and it did not work for me. I configured Dynamic Volt Min to 54.0V and 53.1V are reported to my Victron system. This is too low to maintain full battery until the sun goes down. My battery was discharged down to 92% although enough solar power was available. Unfortunately, I go back to Ramped Targets.
Ive submitted a bug report to Batrium via their support address - The fields only accept integers… I can set the offset to 1 or 2 but not 0.x or 1.x.
Not sure why some have issues saving with the decimal places and others are not from their upgraded systems. For those who do have a issue, watch the following video to be able to assign the typically 0.3V to 0.1V values.
Below are links which would be beneficial to look at to get a better understanding of how to run the BMS. You should be able to find all the answers to your questions there.
After these new hints, configuration is possible for me. The charge cycle worked perfectly to reach 100%. Charging up to 99% was a bit painful for the cells. The first cell already reached bypass voltage at 96% SoC. At this SoC the balancing of this cell makes totally no sense. A little bit later Batrium reduced CVL a bit and the cell voltages recovered. It took about 47mins top-balancing was done, SoC went to 100% and CVL was reduced smoothly to 54V.
This whole mechanism works pretty good. The only exception is, that Batrium should reduce CVL when cells reach bypass voltage and SoC is not yet 99%.
@kleini this sounds like the configuration might not be setup properly as the system does exactly what you describe. Maybe revisit your setup to when the cells reach CV14 parameter the BMS will switch to Limited mode, this then lowers the charging remote targets to adopt the limited values (i.e default offset 0.1V) and also lower the current when set, both configurable.
Above is an extract from the wiki with the trigger points, alternatively if you want us to look at your setup and share how the system is performing over time with our charting, best to send a support email and we can revisit.
You might also find that this session might be the first time in a long time for the system to achieve a fully charged event (all cells), which accrues over time. You will find that future events (we target for once a day) will be much quickly as the system does not need to rebalance as much different between the cells, 7 days difference with a small discharging cell is going to take 7 times longer. Daily we have worked out works well for PV ESS systems.
For others wondering we have been working in BMI on some great charting insights that we are working on the finishing touches, this will be rolled out soon (well before end of 2025).
Before the BMI charting becomes public we will reach out in a separate email to offer those interested a invite to a preview group (using the latest software/firmware release). We are not ready for people to ask to join yet. PLEASE dont ask, when we are ready we will make a separate post here in the community and socials.
Based on our observations, after people reach out for support once they have joined BMI, we find their systems are not working as expected! Only to investigate to find that their systems have been adjusted to a point where rules have overlapping limits preventing the expected behaviour, especially for those with LFP chemistry.
Thanks for your answer, Jaron.
Limiting the charge current is not possible in my system. I feed in to the grid from DC solar chargers. To make them provide full power, the current limits are not applied in my Victron system. So only the voltage limit applies. And even that does not help once the battery voltage and the voltage target are both at the dynamic voltage maximum.
In the battery current graph, you can see, that current drops to about 0A at about 11:37. When the current drops to zero, we can assume, the cells are fully charged. I reduced the bypass threshold 3.45V to reduce overcharging stress for the cells. Other voltages are reduced accordingly. First cell reaches bypass voltage already at 11:10. Batrium goes into Limited mode to recover, and it seems to help. But from 11:16 on, at least one cell remains in bypass voltage, although cells are not yet fully charged.
To sum it up, it already works very well to get cells fully charged. Today, I will reduce dynamic voltage maximum to 55.5V, which is your default for 3.45V bypass voltage. I had to increase by 0.1V due to one CellMate measuring lower voltages in one pack for every cell and all cells do not reach 50mAh bypass session. Let’s see how it behaves today.
Thank you very much for improving Batrium at all and especially in this case. You’re on your way to become the best BMS!
I also have to make the offset parameters to 0.7 and 0.5 because the batrium shunt measure a lower voltage than the sunny island (difference ~0.4volt).
