question

Melih Manisalıgil avatar image
Melih Manisalıgil asked

Lithium Battery Unexpected Voltage Drops

WhatsApp Image 2023-09-27 at 08.12.04 (1).jpegI've got this 12V / 330 Ah Lithium battery setup powering three DC 12V Dometic fridges. They each draw about 6 Amps on average. We've got a Phoenix IP43 12/50 charger and a SmartSolar 100/30 MPPT controller, all managed by the VE.Bus BMS V1. Plus, we're keeping an eye on things with a BMV-702, which shows around 100A of current in and out daily.

When the battery is all charged up, we're mostly running our loads from the charger and MPPT outputs to be efficient. But here's the issue: every 2 or 3 days of use, the battery voltage drops below 11.2V out of the blue.

We've gone through the whole system with a fine-tooth comb, but we're stumped. I'm just wondering if there's something we might have missed. Any help or suggestions would be awesome!

Lithium Batterysmart lithium
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2 Answers
klim8skeptic avatar image
klim8skeptic answered ·

@Melih Manisalıgil Given that the smartsolar is showing that the battery has not been fully charged I would suggest that you are running your battery flat.

Post some screenshots from the batteries showing their status.

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Melih Manisalıgil avatar image
Melih Manisalıgil answered ·

Hello again. @klim8skeptic I am providing the historical datas from charger and mppt. Also battery cells are balanced no problem at all. I think the small DC loads causing unexpected drops.

Attached: PSC cycle #4 and #9; MPPT cycle 13 dats ago is droped voltage values. Battery Status.jpeg


MPPT 5.jpegPSC 6.jpegPSC 4.jpeg


mppt-5.jpeg (73.6 KiB)
psc-6.jpeg (76.9 KiB)
psc-4.jpeg (73.8 KiB)
battery-status.jpeg (65.1 KiB)
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