I have a split bus system for a 12 volt, 400 Ah LiFePO4 house bank on my sailboat. The bank comprises 16 105 Ah EVE cells, 4P4S (4S4P? ... I can never remember ... anyway its 4 cells in paralell then those joined in series).
I charge to 3.6 volts and then hold there until current drops to 20 Amps (0.05C).
Using the REC BMS I have the CHG relay set up to disconnect the bank from the charge buss if any cell reaches 3.7 volts (14.8 for pack). There is a 6 second delay and I have other means to shut off the field current to the alternator during that delay if ever the REC opens the CHG relay.
I have the REC DCH relay set up to disconnect the pack from the load buss if any cell falls to 2.9 volts (11.6 volts for pack).
All good. Here is my problem:
I want to use one of the octocouplers to trip a high voltage warning buzzer if any cell reaches 3.65 volts and use the other octocoupler to trip a low voltage warning buzzer if any cell falls to 3.15 volts (11.6 pack). Obviously I want to have some notice of impending disconnect.
REC advertising materials say these outputs are "user programmable". I am pretty inexperienced with this stuff and find the REC manual a bit confusing.
Questions:
1) Is there a way to program the two octocoupler outputs in this way?
2) Any comment about or disagreement with the voltage thresholds I am considering?
I charge to 3.6 volts and then hold there until current drops to 20 Amps (0.05C).
Using the REC BMS I have the CHG relay set up to disconnect the bank from the charge buss if any cell reaches 3.7 volts (14.8 for pack). There is a 6 second delay and I have other means to shut off the field current to the alternator during that delay if ever the REC opens the CHG relay.
I have the REC DCH relay set up to disconnect the pack from the load buss if any cell falls to 2.9 volts (11.6 volts for pack).
All good. Here is my problem:
I want to use one of the octocouplers to trip a high voltage warning buzzer if any cell reaches 3.65 volts and use the other octocoupler to trip a low voltage warning buzzer if any cell falls to 3.15 volts (11.6 pack). Obviously I want to have some notice of impending disconnect.
REC advertising materials say these outputs are "user programmable". I am pretty inexperienced with this stuff and find the REC manual a bit confusing.
Questions:
1) Is there a way to program the two octocoupler outputs in this way?
2) Any comment about or disagreement with the voltage thresholds I am considering?