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brandon avatar image
brandon asked

Why is my Lithium battery Discharging and shutting off at night?

I am a full-time van lifer that has switched over to a victron lithium system,


See attached photo for current setup.


My issue: the battery is discharging at night and we are losing power. It happens almost nightly and it is the most frustrating thing. I'm seriously losing my mind. It's the middle of summer and losing fridge and fan power daily isn't fun.


We were very happy with our last setup of:

- 2 x 6v AGM dry cell deep cycle batteries (450ah)

- sterling battery 2 battery charger (from the alternator)

- Victron Smart Charger (solar w/ 300 watts)


This system was so basic and never gave us problems, but for weight reasons we wanted to switch over. It's been nothing but a headache and I'm not sure what to do. Any help is greatly appreciated.

Thank you.



BMV Battery MonitorLithium BatteryBMS
battery-schematic.jpg (325.4 KiB)
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Matthias Lange - DE avatar image Matthias Lange - DE ♦ commented ·

What battery do you have now?

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brandon avatar image brandon Matthias Lange - DE ♦ commented ·

victron 200ah lithium smarty battery

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brandon avatar image brandon Matthias Lange - DE ♦ commented ·

Sorry - and it's a 12v system.

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2 Answers
Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

1. The B1 at the shunt have to be after the BP-100, so the BMV also gets shut down if the BMS disconnects all loads.

2. You have a BMV so just take a look at the power draw/the calculated remaining time.

3. You have now less usable Ah than before.
old: 450Ah at 50% discharge -> 225Ah usable
new: 200Ah at 80% discharge ->160Ah usable
-> 29% less usable Ah than before.

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brandon avatar image brandon commented ·

Thank you, Mathias.


Yes, we went slightly smaller because we hardly discharged our last battery below 80%. At night, we are using about 15-30watts depending on if the fridge kicks on or not.

Also, you might need to talk in "Layman's Terms" as I am a pretty green to the victron setup (minus the solar charger we used before).


Thanks again.

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brandon avatar image
brandon answered ·

Thank you, Mathias.


Yes, we went slightly smaller because we hardly discharged our last battery below 80%. At night, we are using about 15-30watts depending on if the fridge kicks on or not.

Also, you might need to talk in "Layman's Terms" as I am a pretty green to the victron setup (minus the solar charger we used before).


Thanks again.

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