I’m asking myself, whether and how the BatteryLife Setting in ESS and the Setting Battery Balancing in DESS makes sense for a Lithium battery like my PylonTech US5000? Especially combined with a dynamic energy contract.
In times with much PV power, the battery would anyway reach a state close to 100%, enough for the PylonTech BMS to balance cells if necessary. In times with little or no PV, but high variations of prices per kWh on provider side (in my case Tibber), it happens, that DESS buys from grit to bridge a day with high prices like today, see screenshot. That also leads to 100% SOC, again enough for the BMS to balance cells.
So, does the BatteryLife option in ESS make sense in such a scenario with Lithium BMS batteries?
My conclusion so far: Either PV or pro-active grit to battery will lead to charge levels of close to 100% from time to time anyway. Just as last fallback, I enabled Battery Balancing in DESS every 60 days. But I switched off BatteryLife in ESS.
Does that make sense?
How often does a modern Li BMS battery need balancing?
Batterylife is really more for Northern hemisphere regions where seasonally, you aren’t guaranteed to fully charge regularly, so the system auto adjusts minima to keep batteries in the balancing zone more regularly.
Some battery manufacturers also want it enabled so batteries fully charge.
DESS and ESS with batterylife have rather conflicting objectives. With DESS it has other priorities, being fully charged is not one of them, so the balancing is a failsafe.
DESS will never start to balance if the battery has been able to naturally get to 100% within the time period you set, and stayed there for time you want it balance for.
Typically you either run as a DESS or as a native ESS because they have different objectives.
So I have neither activated battery life nor battery charging in the DESS with LEP cells. Victron itself states in its description that battery life is mainly intended for lead batteries. Since my system regularly reaches 100% soc anyway and I regularly observe how the cells are balanced, I see no reason for this. What I do do manually when I have particularly cheap purchased electricity is increase the Min Soc, which leads to a higher charge. On the following days, when the purchasing prices are not quite so cheap, I gradually reduce the Min Soc to 15%.
This is an incomplete, or rather, a dated statement.
From the docs:
This feature has several advantages:
• Operating around a low state of charge shortens the life of lead/acid batteries.
• Certain lithium batteries also need to be fully charged regularly in order to balance their cells. This includes the Victron 12.8V lithium batteries, for which it is mandatory to enable BatteryLife.
• In case of mains failure - having no spare energy available from the batteries to power the loads defeats the whole purpose of having a battery back-up.
