I’m using a 3 x 15kVA Quattro system with Smart LFP battery bank with the Victron Smart BMS. The system is powered by a generator which is steered bij de generator start/stop functionality of the Cerbo based on SOC. I cycle the batteries between 30%-90%. The consumption is quite high and I do as much as 3 cycles a day.
Therefore it is important that I balance the batteries at regular rate. However, I’m surprised there is no functionality within the generator start/stop menu to accomplish this. There is the Periodic Run which allows you to run the generator until battery is 100%, but that doesn’t mean the batteries are balanced? I would need 2 hours in absorbtion. I didn’t test the Periodic Run thoroughly, does it stop at the moment the SOC becomes 100% or it keeps running for a while?
Having a hybrid system with Lithium batteries cycling on a diesel seems a major application to me. Such automatic balancing functionality seems a prerequisite for this application.
The main issue here is that diesel generators don’t like to rum on a very low load, less than 25% load leads to problems. So, here it’s best practice to cycle the batteries between ~20% soc and 80% soc, with limited balancing. Full charge balancing only then needs to be carried out periodically.
If you are running 3 cycles a day, this probably violates any warranty - this is usually limited to one cycle per day. Consider a much larger battery bank. Alternatively, if the system has no PV input, then restrict the battery use, and run directly on generator, this is more efficient.
I understand the problem of charging below 25% and this will happen if there is no consumption besides the balancing. But there is consumption and it is easy to program the balancing on a moment there is a guaranteed consumption > 25%. You suggest to do the pediodical balancing manually? Even if you do only 1 cycle a day it is desirable to initiate the balancing automatically even if you limit the number of full charge balancing.
This setup is temporary, the average number of cycles/day during the lifespan of the setup is below 1 cycle/day. It is still worthile to run the generator at 80% load instead of 25% I think because I don’t expect the cycle life of the batteries will limit the lifetime of the installation.