I've got a solar setup with four 300W panels in series, paired with a 12.8V 200Ah LiFePO4 battery and a 2000W HzSolar MPPT hybrid inverter. My goal is to have everything powered by solar when it's available, with the battery kicking in otherwise. I want the AC to turn on when the battery drops to around 20% to help prolong its life. However, I keep running into an issue where my battery is draining down to about 7.5V, which causes the inverter to shut off. Once it's off, I can't charge the battery, so I have to temporarily jump it with my car battery just to get it back up to 10.5V. I've made some changes to my inverter settings to try and fix this, like adjusting the charging current and the solar prioritization. I'm wondering if my solution is sound or if there's a better way to prevent the battery from draining so low. Additionally, I'd like to know if there might be any underlying issues with my battery or inverter that could be causing this.
2 Answers
It sounds like your battery's BMS (Battery Management System) might be cutting off before the inverter shuts down, which is possibly why you're seeing that low voltage issue. Have you tried adjusting the inverter's low voltage disconnect? That could help keep things running longer before the battery hits critical levels. Also, do you have the option to connect communication cables between your inverter and battery? That might help with monitoring and adjustments!
Be cautious with your lithium battery! If it's getting dropped below 9V too often, it might become permanently damaged. That could be a big problem down the road. The good news is that it sounds like it's just the BMS disconnecting rather than a total failure.
Thanks for the heads up! I was worried it might be something bigger, but hopefully it's just the BMS cutting off as you said.
I actually adjusted the low voltage disconnect to 11.5V, up from the default of 10.5V. And for communication cables, I'm open to adding anything—what exactly do you recommend?