Tuesday, April 23, 2013

12V battery pack initial charging


Before buying the LiFePO4 cells for the 72V battery pack I wanted to make sure that the cells for the 12V battery pack were ok. Each of the cells were measured to have a voltage of exactly 3,30V after shipping which indicates that the cells would be in good condition. 

The cell balancing modules were connected parallel to each cell and a laboratory power supply was used to charge the battery pack. The cell balancing modules will be located in a separate enclosure and the connection to the cells is made by 1,5mm^2 wires. Each of the wires have a fuseholder that is located as close to the cell terminal as possible. The fuses will act in case a short circuit occurs and they are also helpful when connecting electronics to the balancing circuits and protection circuit module. The connections can be made safely first and after the connections are ready the fuses can then be placed in the fuse holders.

After two days of charging with a current of about 0,8A the battery pack was fully charged up to 14,4V and the balancing circuits seemed to work as expected. I will not make any deeper tests to the batteries at this point. They look to be in good shape and I am ready to order the cells for the 72V battery pack.

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