LiFePO4 what should be the setting on my charge controller/inverter for LBCO?

round4

Schneideer/xantrex has a default setting of 48 volts for the LBCO. Will discharging to this voltage level hurt my LiFe PO4 Fortress battery, or reduce the life cycles? Fortress recommends 50.5 volts, but that is not an option on my equipment.

mcgivor

Welcome to the forum.

And welcome to the club, the LBCO is an issue I'm sure will be addressed sooner or later by Schneider as they are working in conjunction with other battery manufacturers which require a higher value. Perhaps there will be a firmware update in the near future to address this, but for now it appears 48V is the maximum. The value is still safe, what voltage dose the BMS cut off discharge? Actually I'm in the same boat but never get so low to be of concern.......yet.

mvas

Please, post a URL to the datasheet of the exact model battery.

50.5 volts / 16 cells = 3.1 volts per cell = shallower but more cycles,
48.0 volts / 16 cells = 3.0 volts per cell = deeper but fewer cycles

Total Energy = sum of all ( kWhrs per cycle x number of cycles )

What is the net difference in total ( sum of all ) kWhrs generated between the two depths of discharge?
Contact Fortress and ask them exactly how this deeper discharge will affect the number of cycles and net kWhrs generated.

dehv

Not sure about your LiFePo4 cells, but my old a123 cells can be safely discharged down to something in the neighborhood of 2v without damage (according to mfg.) when the current drops off essentially - something around 95percent discharge.

ElectricLove

With all LFP cells 3.0V per cell isn't really a damaging low-point, unless fortress isn't using LFP chemistry or they are being extremely particular so they can make some warranty commitments.  LFP cells are spec'd with 2.80V or 2.85V as their "0% SOC" point, reality is they still have a little juice left at that point all the way down to 2.5V, some manufacturers even throw 2.0V on a graph (A123) but if you really discharge to 2.0V per cell often it will lead to some long-term damage of the cell.  Manufacturers are all making the same batteries with very little differences between cells but each company decides how they want to manage the customer expectations and features/benefits and warranty/lifespan issues so you get a lot of variation...

You should not worry at all that your LBCO is 48.0V, your system will hardly ever see it (unless you didn't spec it properly) and when it does it will result in approximately zero damage to the battery cells.  The BMS in your Fortress battery most likely has 2.5VPC as its low-voltage cut-off (40.0V) so at 3.0VPC (48.0V) LBCO you won't even come close to that number.

I have toured many Lithium battery factories and have many years of experience in this field working with LFP technology.