SOC keeps clearing around 50%

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downbeathunter asked Aug 22, '22

SOC keeps clearing around 50%

Greetings.

New to all this, but trying to run a small load (dc fridge & lights) in little travel trailer.

280Ah LiFePo4 & BMV712. I have 2 Victron solar chargers, but they are currently disconnected while I figure this out. BMV is running most recent firmware (4.08)

Charging is fine (Aims 75amp). If I discharge quickly (200W/hr) everything seems normal, SOC decreases steadily until I stop it at around 10% SOC. However, if I let it run with a small load (just the fridge ~ 35Ah/Day) it runs for 3-4 days, gradually decreasing SOC & increasing "Ah used" and then these figures just clear themselves - no values shown.

Pics included;

home screen with voltage but no SOC/Ah Used
"trends" showing the last week with a quick discharge, recharge and then 3 days slow usage until it just ends
battery settings.

For what it's worth, BMS voltage matches the BMV's pretty consistently.

Any thoughts would be appreciated!

SOC

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Modifications Space

Node Red Space

Answer 1 · 2022-08-22T14:35:39Z

johanndo answered · Aug 22, 2022 at 02:35 PM

Your battery BMS likely freaks out because of deep discharge and disconnects the loads, killing all Victron sensors, so when power gets bac on they start over to synchronize.Seems either your battery capacity is wrong or you have imbalances, that cause disconnects / shutdown of your bmv/cerbo.

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downbeathunter commented · Aug 22, 2022 at 02:43 PM

Thanks for the thoughts, interesting angle, however the BMS is set for low voltage cutoff of 12v (or 3/cell) and shows no cutoffs in it's history. (JBD BMS)

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