This is a DeWalt DC9280 28V. pack.

It contains eight, 2.3Ah A123 cells.

DeWalt also sells a 36V. pack (DC9360) that contains 10 of the same cells.

A “Security Bit” is needed to remove the screws in the top cover of the pack. 

I purchased the set shown above at a local Harbor Freight store.

Once the screws are removed, carefully remove the yellow cover.

Use great care in clipping wires so as to not create ANY shorts, as spectacular  fireworks are possible.

The eight cells are interconnected with spot-welded bands.

On the end opposite this view, one band can be cut, thus creating two, four-cell packs.

The cut can be seen between the middle two cells on the bottom of this picture. The two packs are then ready to add balancing and output leads.

Shake the cells out of the case - they are a close fit - and remove and discard the black end plates.

I choose to “fold” the pairs of cells as shown, as that configuration better suits the space available in my RC model planes.

This configuration is not unhandy for my QRP radio purposes, so I make all my packs the same and use them interchangeably.

I put a balsa spacer in the fold between the cells to prevent shorts and to make it easier to solder the  battery pigtail (balancing leads) onto the interconnecting bands.

Here one of my four-cell A123 packs is connected to my FMA Direct Cellpro 4s balancing charger. The 4s charger requires a 13.8V. dc supply.

Battery Pigtail leads (for balancing connections) are also available from FMA Direct.

More Uses for A123 Batteries