2 Victron EV Chargers goes below SOC till black out

Q&A and troubleshooting EVCS
,
1

I am experiencing an issue with an installation and hope someone can help me. Here is the situation:
ESS with 3x 5kVA MultiPlus-II and 28kWh of Pylontech batteries. Grid is 3x25A, Netherlands.
2x Victron EV Chargers (NS) connected to the AC-out1 of the MultiPlus-II.
Minimum SOC in VRM is set to 15%.

The problem
As long as only one EV charger is used, everything works fine. However, as soon as both chargers operate simultaneously, problems arise:

  1. The system pulls 25A from the grid and the rest from the batteries, causing the batteries to drain rapidly to the minimum SOC of 15%.
  2. While charging, the system continues past the minimum 15% SOC, dropping from 15% to as low as 4%. At this point, the batteries shut down. Then, both chargers suddenly start charging at maximum capacity, which causes the power demand to exceed 35A+. This trips the main fuse, leaving the customer without power in the house.
  3. The result is a complete power outage in the house.

Once the minimum SOC is reached, I want the EV chargers to draw power only from the grid and not from the batteries. The SOC limit is there for a reason. This means that both chargers must share the available 3x25A grid connection capacity. Dynamic Power Sharing or Load Balancing should solve this issue. According to the manual, this should work.

Does anybody have any suggetion?

SOC #1
SOC #1643×1387 79.5 KB

SOC #2
SOC #2953×721 52.7 KB

SOC #3
SOC #3957×710 50.6 KB

2

Hi,
Anybody from the Victron EVCS or @Lpopescu have an answer? Because of the problem our clients with more as one Victron NS charger are not able to charge there cars safely, because the mainfuse will blow. How can I solve this problem? Thanks

3

Hi, I think there are some misunderstandings:

  • that SOC to stop charging is for off grid mode
  • EVCS in a Victron system will behave like any other consumer, consume from battery as long as it is changed, then from the grid.
  • each EVCS will try to consume less than the maximum available current, but if there is more than one, probably also combined with other house consumers, it is possible to have overloads. Remember that the EVCS must “see” the overload and then it will react. It can’t predict the consumption and react before. And depending on how fast the fuse is, it can trip faster or slower.
    We are working on a centralized system to control multiple charging stations, but it will take a while. Until then, I would advise the customer to limit the EVCS power to the minimum, to avoid situations like this. Or maybe and automated node-red flow, to limit the EVCS to a low current when the battery is lower than a certain level?!? That might solve this issue.
    But again, the rest of the house is consuming as well, so if you limit both chargers to 6A, x2, there are still only 13A left for the rest of the house. So the fuse can still blow.
    I’m just sharing some thoughts here.