Battery only discharges to 32% - but why?

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shadowblues asked Feb 7, '23

Battery only discharges to 32% - but why?

Hi,

I have a Victron MP2 setup with attached DIY battery (16S, 280Ah). In the ESS assistant, I have set the low values to stop discharging to 46V when discharging slowly and to 45V when discharging above 0.1C. I have not set any value to 47V - at least not any I remember :-)

The BMS is configured to even lower numbers (44.5V).

However, the battery stops discharging in Mode 1 without battery life setting at 32%, 47V. I wonder why it does that and what I have to change to drain it to lower values.

Best regards,

Roger

Multiplus-II Lithium Battery discharge level

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Answer 1 · 2023-02-07T09:08:16Z

Meine_Energiewende answered · Feb 07, 2023 at 09:08 AM

That are very low values for a 16s pack. Are you sure, that the system will go that low ? The remaining energy of a lifepo4 cell under 3 volts is maybe 2-4 percent and not worth damaging the cell.

Jens

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shadowblues commented · Feb 07, 2023 at 09:34 AM

Hi Jens, thank you for pointing me on that. I took the usable range from other postings. I just looked up the charge / discharge curve and I think you are right. However, I would find it better if the system would obey to my demands :-) So I will assume that 47V is a hardcoded low value then? The odd thing is that the ranges suggested by the ESS wizard are below this value. I will try to change the settings in my BMS so that it reflects the actual values.

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