16 cell 12v battery. What is the best configuration?

If pre-balancing is necessary, there are a couple common methods for pre-balancing cells:

Method 1: Charge all cells individually. Before assembling the cells into a pack, each individual cell may be charged independently by using a battery charger designed for a single lithium ion cell. It is essential that if this method is used, the charger MUST be configured so that it does not overcharge the cell. Never leave a cell charging without an automatic method for shutting of the charger.

Method 2: Put all cells in parallel and fully charge together. Before assembling the pack, cells can be connected in parallel and charged together. This method may not work with some types of cells or if the cells are significantly out of balance, as significant currents may flow from one cell to another. Current flow can be calculated by taking the difference in voltage from the lowest to highest cell and dividing by the internal resistance. If you are unsure if current will flow or if you are using a chemistry other than iron phosphate, use one of the other methods. The charger must be setup with a maximum voltage no higher than the maximum cell voltage specified by the cell manufacturer. In order for this method to work, cells must have a charge applied while in parallel (simply connecting in parallel will not allow enough current to flow to balance the pack.)

Method 3: Measure voltages of each cell and manually adjust using a charger or load. This is the most difficult method, but it may be significantly faster than the others if only a small number of cells are significantly out of balance while the rest of the pack is well balanced already. This is an especially useful technique after a cell in a pack has been replaced. Use an isolated load or isolated charger to manually adjust the state of charge of the particular cell requiring adjustment to bring it into balance with the rest of the pack. Careful attention must be given to ensure that a cell is not over charged or over-discharged with this method. This method can be used to balance a cell after it has been assembled into a series pack, but it is absolutely essential to ensure that the load or charger is isolated so that a short circuit is not created within the pack.

Method 4: Have the manufacturer “bin” the cells. While this is not usually an option for small scale systems, in production environments, cell manufacturers can “bin” the cells and match them based on current state of charge, internal resistance characteristics, and cell capacity. Building a pack using cells which are all approximately the same not only eliminates the need to pre-balance, but also keeps the pack in the best health long term since all cells are likely to age similarly.