LifePo4 Voltage at .5C - .6C Discharge
Our two GC2's (with 100% charge) drop below 12v while under a 100a - 125a load. When they reach 50% (at 100a - 125a), voltage drops into the low 11's while under-load. What kind of under-load volt...
Forum Discussion
Itenerant1, how did the sequence work when you had your BMS shut-down when one of your cells "went rogue"? In particular, how did you get your Magnum to light up so you could use its charger with the House batts shut down?
EDIT, read this again and not sure it applies. Might be he only lost his BMS but still had 12v "unprotected" until he got that fixed. Was "dead in the water" too for a time there? so might apply?.
My question is about the inverter/charger needing to have 12v before you can use the charger at all with a low voltage BMS shut-down.
-RE: Lithium Battery Question by Itinerant1 :
"I don't know how the dropin batteries work as far as disconnecting that's why I asked. On my system there are 2 solenoids, an over voltage disconnect and under voltage disconnect which will stop the charging or discharging but keep the batteries powered.
For instance at the tail end of last year I had a sense board go out on one of my strings which shut the entire system down (dead in the water)
one of the safety features of my system is it has to see all 20 cells or it will shut down protecting the batteries. I had to do a 5 minute rewire to bypass the selenoids but doing this I was using my batteries without any protection at all.
After 3.5 years and felt fairly confident that if I lowered my charging to 13.9v and kept 13.6 float I should be ok. I got busy doing other things for 3 months and by the time a got new sense boards installed and rewired the solenoids back for protection I set the generator like usual to charge at 100a and set absorb voltage to 14.2v. During the absorb I had 1 cell that would go to 3.8v (the balancer wasn't able to burn off enough) which would disconnect charging but still kept the batteries powered (it would do this with solar also). I had to lower my charging to 14.0v absorb which was keeping that one cell from hitting 3.8v and letting the balancers start doing their thing of charging the other cells and catch up. It took about 2 weeks of doing this in steps of 14.0v, 14.1v, 14.2v after all the cell got within 40mv of each other like they always have been I lowered it back to 14.1v and all is good. I should also note it took that long for the SOC capacity to reset itself because it could never get the voltage per cell high enough for a reset."
EDIT, read this again and not sure it applies. Might be he only lost his BMS but still had 12v "unprotected" until he got that fixed. Was "dead in the water" too for a time there? so might apply?.
My question is about the inverter/charger needing to have 12v before you can use the charger at all with a low voltage BMS shut-down.
-RE: Lithium Battery Question by Itinerant1 :
"I don't know how the dropin batteries work as far as disconnecting that's why I asked. On my system there are 2 solenoids, an over voltage disconnect and under voltage disconnect which will stop the charging or discharging but keep the batteries powered.
For instance at the tail end of last year I had a sense board go out on one of my strings which shut the entire system down (dead in the water)
one of the safety features of my system is it has to see all 20 cells or it will shut down protecting the batteries. I had to do a 5 minute rewire to bypass the selenoids but doing this I was using my batteries without any protection at all.
After 3.5 years and felt fairly confident that if I lowered my charging to 13.9v and kept 13.6 float I should be ok. I got busy doing other things for 3 months and by the time a got new sense boards installed and rewired the solenoids back for protection I set the generator like usual to charge at 100a and set absorb voltage to 14.2v. During the absorb I had 1 cell that would go to 3.8v (the balancer wasn't able to burn off enough) which would disconnect charging but still kept the batteries powered (it would do this with solar also). I had to lower my charging to 14.0v absorb which was keeping that one cell from hitting 3.8v and letting the balancers start doing their thing of charging the other cells and catch up. It took about 2 weeks of doing this in steps of 14.0v, 14.1v, 14.2v after all the cell got within 40mv of each other like they always have been I lowered it back to 14.1v and all is good. I should also note it took that long for the SOC capacity to reset itself because it could never get the voltage per cell high enough for a reset."
