Wildernessbob
New Member
Hey everyone,
ok, i think i know how a BMS is supposed to work, but maybe not. i have a brand new Litime 12v 200AH battery, setup the litime battery monitor, and have it connected to an Aims inverter charger. i fully charged the battery, fully discharged the battery until the BMS shut down, and programmed the monitor. this is a backup system for my well sanitizer, so it's not a heavy load and i've only used it once since it was installed at the end of the winter season when we have our power outages. and because of that, i turned off the battery charger on the inverter so the battery could rest at 80% until next season. unfortunately the inverter requires 12v input in order to work even in bypass mode, which i didn't know. so there was a constant 8W draw and i "forgot" to turn the charger back on. so the battery drained down completely, and this is where i get confused, to 8.82v before the inverter stopped functioning and i lost power to my system. so, the question is, should the BMS have not shut down the battery @ 10v? because now i can't charge the battery with the inverter because it needs >10v to operate, and my smart battery charger will not recognize the battery. that's problem #1. ok, i need a 0v charger, fine. problem #2, surely i can't be expected to have to monitor the battery every time the system is used and disconnect it when it gets down to 10V. what if it's the middle of the night? go up to the shop in my jammies to disconnect the battery, in the dark!
i won't even know when it gets to that DOD because i can't monitor it from my house. am i missing something or did the BMS not function correctly? the whole system has all sorts of parameters and safeguards doesn't it? the charger has settings to monitor the charge to prevent over charging, as does the BMS, and it has settings to shut down at specific DOD as does the BMS. i would have thought that it's pretty much turn it on and walk away, more or less. normal mains power supply, the inverter/ charger bypasses power to my well system, monitors the battery SOC and keeps the battery safely at 100%, while BMS is also monitoring the charge and battery to make sure it's within parameters and not overcharged, too hot etc. then when the mains power is interrupted, the inverter switches to inverter mode draining power form the battery to keep the well system running. when mains power is restored the charger checks the battery SOC and begins charging again. now, i would have thought that should the mains power remain off long enough that the battery SOC drops to the set point in the inverter/ charger, it's supposed to turn off, and if that fails, and the inverter remains on, the BMS will continue monitoring the battery and when it detects the battery voltage to be below the industry standard set point of 10v for LiFePo that it would then turn off the battery. when mains power is restored all should go back to normal, right? am i. missing something?
ok, i think i know how a BMS is supposed to work, but maybe not. i have a brand new Litime 12v 200AH battery, setup the litime battery monitor, and have it connected to an Aims inverter charger. i fully charged the battery, fully discharged the battery until the BMS shut down, and programmed the monitor. this is a backup system for my well sanitizer, so it's not a heavy load and i've only used it once since it was installed at the end of the winter season when we have our power outages. and because of that, i turned off the battery charger on the inverter so the battery could rest at 80% until next season. unfortunately the inverter requires 12v input in order to work even in bypass mode, which i didn't know. so there was a constant 8W draw and i "forgot" to turn the charger back on. so the battery drained down completely, and this is where i get confused, to 8.82v before the inverter stopped functioning and i lost power to my system. so, the question is, should the BMS have not shut down the battery @ 10v? because now i can't charge the battery with the inverter because it needs >10v to operate, and my smart battery charger will not recognize the battery. that's problem #1. ok, i need a 0v charger, fine. problem #2, surely i can't be expected to have to monitor the battery every time the system is used and disconnect it when it gets down to 10V. what if it's the middle of the night? go up to the shop in my jammies to disconnect the battery, in the dark!
i won't even know when it gets to that DOD because i can't monitor it from my house. am i missing something or did the BMS not function correctly? the whole system has all sorts of parameters and safeguards doesn't it? the charger has settings to monitor the charge to prevent over charging, as does the BMS, and it has settings to shut down at specific DOD as does the BMS. i would have thought that it's pretty much turn it on and walk away, more or less. normal mains power supply, the inverter/ charger bypasses power to my well system, monitors the battery SOC and keeps the battery safely at 100%, while BMS is also monitoring the charge and battery to make sure it's within parameters and not overcharged, too hot etc. then when the mains power is interrupted, the inverter switches to inverter mode draining power form the battery to keep the well system running. when mains power is restored the charger checks the battery SOC and begins charging again. now, i would have thought that should the mains power remain off long enough that the battery SOC drops to the set point in the inverter/ charger, it's supposed to turn off, and if that fails, and the inverter remains on, the BMS will continue monitoring the battery and when it detects the battery voltage to be below the industry standard set point of 10v for LiFePo that it would then turn off the battery. when mains power is restored all should go back to normal, right? am i. missing something?
