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FAQ: Handling a cell with a low voltage

Question: I have received the shipment of the batteries. Upon arrival I checked visually the batteries, they were OK. Few days later, BEFORE any use, I was ready to give them the first charge according to your instructions on the web site. I checked the batteries voltage using a digital multimeter and one of them (one cell) showed a low voltage of 1.28V.  What is wrong with this cell?

Answer: As explained in the support article, the cells are shipped partially charged. The usual voltage of the LFP cells is 3.2V.  In quite rare case the cell may get slowly self-discharged. The voltage may drop bellow 3.2V.

We suggest the following: connect the cells to a regulated voltage supply (typically a laboratory power supply). Increase the voltage slowly (with a low charge current) to see if the cell aborbs energy. If so, the voltage of the cell will slowly increase back to the regular voltage level. If the voltage restores back and stays in the regular voltage level, the  cell may be fully OK.  As the  next step make the full charge of the cell and see how it behaves. You may wish to perform one or two cycles with the cell to see the cell performance and perhaps to measure the capacity.

Note: In case the voltage of the cell does not increase, or increases slowly, or drops back again bellow the regular voltage level  (3.2V), the cell may have some internal defect. We suggest you do not charge this cell. Leave the cell without charging and contact us for the RMA process.