Hey everyone, I'm reaching out for help with my solar battery system. My capacity test yielded just 28 hours, which is way below what I expected. Here's what I've got: I measured the energy consumption of my appliances using a Kill A Watt, which showed they use about 3.18kWh over a 24-hour period. To power my appliances for 48 hours, I need around 6.36kWh. I've connected three 24v 100ah LiFePo4 batteries in parallel. Even with an efficiency of only 80%, I should theoretically have about 6.14kWh available. But managing only 28 hours feels ridiculous! I suspect there might be an issue with my inverter. I'm planning to disconnect all batteries and test each one separately to rule them out. Any insights on what I might be missing?
3 Answers
Have you got a shunt in place to measure energy drawn from the batteries? That could really help you figure out if the issue is with your batteries or the inverter. I had a Growatt inverter once that wasted quite a bit of power because of its high idle consumption.
First thing to do is monitor the actual discharge of your batteries. It sounds like you might be pulling more energy than your estimates. If your BMS shuts down the batteries before reaching full discharge, you can’t assume your rated capacity is accurate.
I get that, but even with those adjustments, 28 hours feels really off. I might have a deeper issue to address.
How do I set up monitoring for battery discharge?
Your inverter likely has some inherent losses; it’s usually around 10% but can be worse with lower-quality models. Also, make sure you check the individual capacities of your batteries. If one of them is bad, it can throw everything off.
Yeah, all batteries were balanced and fully charged before the test.
I checked, and it's not a battery issue. They were all charged and balanced, plus I'm using a Victron shunt.