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Discharge voltage of LFP Smart 12.8 V 200 Ah batteries

Curious to find out what voltage users are getting from their 12.8 V 200 Ah Smart LFP batteries during a mild discharge (say less than 0.1 C). This is the latest generation, temporarily labelled -a, that is now the standard model.

I am monitoring a new installation via VRM (the lockdown in France doesn't give me access for now) and have consistently low voltages compared with the discharge curves published by Victron: the difference is in the order of 0.6 V. There is no satisfactory explanation to this so far. Any clue? What are you getting from your new LFP Smart 12.8/200?

Details about the observation

Voltage measurement has been checked by the installer on the batteries directly and is consistent with VRM data.

The Victron document I am referring to is the "Lithium Battery Manual", rev.00 dated 30/09/2020. The discharge chart appears on page 27. For example, at 10% DoD, cell voltage should be a little over 3.4 V, so an expected battery voltage greater than 13.6 V; I am getting 13.0 V.

To my knowledge, Victron didn't really state how they managed the size and weight loss with the new batteries; I am assuming that the above charts apply to the new batteries, but is this correct?

Cells are balanced. The whole installation is Victron, built around a MultiCompact Plus 12/2000/80 and managed by a VE.Bus BMS.

After fully charging the batteries (two in parallel), we read 3.40 V ±0.01 V per cell at rest, so 13.59 V per battery - well below the 14.2 to 14.4 V I would expect from the discharge chart.

Many thanks in advance for any help, guidance, advice...

Lithium Battery
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jl06 avatar image jl06 commented ·

Just noted that there is a more recent edition of the "Lithium Battery Smart Manual": Rev01 03/2021. This latest version has exactly the same discharge curves.

Also, I have received feedback from another user: they are also measuring much lower voltages than the curves in the manual show (13 to 13.1 V at SOC in the range 90 to 80%, vs. approximately 13.6 V in the manual).

Four batteries with the same measurements... looks like this could be related to the chemistry of the new batteries? Would anyone from Victron have the answer?


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