Float lithium?

1

Hi community

I have install the batrium in a boat all equipment is victron and connected with cerbo via can
Everything runs fine but whatever i do i cant float at 3.350v or lower the voltage and power the demands from there
I’ve searched everywhere read also another post here but nobody seems have done that
It is strange because i was expecting that bms to be very smart :thinking:

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2

You may find your answer here.

https://community.victronenergy.com/questions/28493/force-a-quattro-into-float.html

3

Thank you but this is not what i want
Since the batrium is can connected i would expect the batteries to go to a lower voltage and stay there
My inverter/charger is doing that but i want the bms to take care of it
The thing is that i cant find the correct settings to do it since they dont have them

4

The Batrium BMS will not issue a command to change to a float voltage setpoint to the Victron system. And the Victron system will maintain charge voltage at the BMS setpoint value indefinitely. Unfortunately this is the current state and there is no configuration setting that will change that behavior. In my opinion this is a shortcoming of the Victron equipment, not a Batrium issue. The BMS is a protection system and not a charging system.

I have a Batrium BMS connected to a Victron Cerbo running an off-grid system. From my personal experience I can provide the options available to you, as I have used all of these myself.

Option 1: Wait for Batrium or Victron to add the feature someday.

Option 2: Set your BMS charge setpoint to your desired float voltage, then forego the absorption charge mode. Your batteries will still charge to full, but it will take longer to get the last several percent of charge. Also, lower your cell balancing setpoint to match the lower charge setpoint.

Option 3: Install Victron’s Venus OS Large onto the Cerbo, then use Node Red scripting to change to float voltage. In this configuration you’ll have several options available, depending how you set up your script such as:

  • C-rate termination: switch to float when the charge rate falls to a specific current while at the absorption setpoint.

  • Time termination: switch to float when the pack voltage is at the absorption setpoint for a specific period of time.

  • BMS termination: switch to float when the BMS signals full (all cells balancing).

If you’re looking for an easy to implement approach, from my personal experience Option 2 (lower setpoint) works very well when the primary charge source is solar. The lower available solar power near the end of the day matches the lower charge current accepted by the pack. But if you have some technical ability, Option 3 (Node Red) offers the ability to control the system exactly to your requirements.

I’m willing to provide a drop-in script for any of the listed profiles, all you’d need to do is install Node Red and there are many tutorials available online which show how to do it.

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