Low battery condition, now BP error

The system ran fine but now we are getting a BP error. It was running on battery at night and around 5:00am, the whole system cut off. Now the voltage on the batteries when testing with a multimeter is around 3V. We then proceeded to hook up the generator to the inverters but it's not recharging the batteries and the inverters will not power on and provide AC output power. I'm considering buying a 48v charger and plugging it into the generator to charge the batteries. Any advice would be amazing.

Pandemoniumppk said:

The system ran fine but now we are getting a BP error. It was running on battery at night and around 5:00am, the whole system cut off. Now the voltage on the batteries when testing with a multimeter is around 3V. We then proceeded to hook up the generator to the inverters but it's not recharging the batteries and the inverters will not power on and provide AC output power. I'm considering buying a 48v charger and plugging it into the generator to charge the batteries. Any advice would be amazing.

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Batteries got emptied and they're in protection mode. 3V is too low to count as a battery, so it's giving you an error.

Yes. Get a 48V charger AS LONG AS the charger can charge a 0V battery. Some chargers refuse to charge if the voltage is too low. 3V may register as open circuit to the charger, and it may refuse to charge.

IMHO, any 60V/5A supply of your liking. You know it will absolutely, positively output a voltage regardless of what the battery voltage is. 5A isn't much, but it will get it back into the operating range where you can charge via PV and/or AC input.

Make sure you adjust your cut-off voltage so that the inverter shuts off BEFORE the BMS engages in protection. 48V doesn't leave more than 5-10% on the table. Avoiding BMS protection will allow the inverter to start charging in the morning from PV or anytime from generator (provided it's reliable - some units need inverter-generator power and can't tolerate the dirtier power from standard generators).

Thank you! That is very solid advice and I appreciate it. You are right that the bms was in LVD mode and we put 4 12v batteries in series to get 48v and "jump started" the battery bank, then turned on the inverters successfully, and when the charge light came on, we removed the connection to the temporary batteries.

Pandemoniumppk said:

Thank you! That is very solid advice and I appreciate it. You are right that the bms was in LVD mode and we put 4 12v batteries in series to get 48v and "jump started" the battery bank, then turned on the inverters successfully, and when the charge light came on, we removed the connection to the temporary batteries.

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Glad you had the option.

Now that you're back online, make sure you set your cutoff voltage high enough the BMS does not force protection. You likely need to leave about 5-10% in the battery to ensure it can power the inverter until you have a charge opportunity. 48V is a good starting point.