dogfud
Doing the Needful
Sorry if this is a noob question, but I'm trying to understand if this is typical BMS behavior or not. When charging a 4S 48V bank of Amperetime 200AH batteries, if I remove the charge current suddenly there is a major voltage sag that lasts about 1.75 seconds and causes my inverter to fault. It seems like the BMSs take a while to switch from charging back to forward current ..
Here's a picture of the drop measured at the battery when I disconnect my bench supply (120VDC/3A) from the PV input on the MPPT charger (Victron 150/70). Voltage drops from around 54V to under 10V then recovers after 1700mS or so. Inverter load on the DC side is maybe 1A, and the batteries are connected to the bus with 1/0, and 4AWG to the inverter, so it really seems like a BMS thing...
And here's what it looks like when I just flip the breaker disconnecting the MPPT charger from the bus bar, again DC load is maybe 1A from the inverter. The inverter (Victron Phoenix 48/1200) faults and shuts down of course.
Maybe its no big deal since PV panels don't just cut out abruptly in the wild, but I just wasn't expecting the BMS to react so sluggishly like that?
Any thoughts appreciated, thanks.
Here's a picture of the drop measured at the battery when I disconnect my bench supply (120VDC/3A) from the PV input on the MPPT charger (Victron 150/70). Voltage drops from around 54V to under 10V then recovers after 1700mS or so. Inverter load on the DC side is maybe 1A, and the batteries are connected to the bus with 1/0, and 4AWG to the inverter, so it really seems like a BMS thing...
And here's what it looks like when I just flip the breaker disconnecting the MPPT charger from the bus bar, again DC load is maybe 1A from the inverter. The inverter (Victron Phoenix 48/1200) faults and shuts down of course.
Maybe its no big deal since PV panels don't just cut out abruptly in the wild, but I just wasn't expecting the BMS to react so sluggishly like that?
Any thoughts appreciated, thanks.