Method and apparatus for connecting a plurality of battery cells in series or parallel

1. A battery pack comprising:

a housing;

a first set of plurality of battery cells connected in series and positioned in the housing;

a second set of plurality of battery cells connected in series and positioned in the housing;

a first analog front end connected to the first set of plurality of battery cells and configured to individually monitor each cell of the first set of plurality of battery cells;

a second analog front end connected to the second set of plurality of battery cells and configured to individually monitor each cell of the second set of plurality of battery cells;

an electronic processor connected to the first analog front end and the second analog front end;

series connection contacts configured to connect the first set of battery cells and the second set of battery cells in series when closed; and

parallel connection contacts configured to connect the first set of battery cells and the second set of battery cells in parallel when closed,

wherein one of the series connection contacts and the parallel connection contacts are closed when directly engaged by one or more conductive blades of an external electronic device,

wherein the other of the series connection contacts and the parallel connection contacts are opened when directly engaged by one or more insulating ribs of the external electronic device.

2. The battery pack of claim 1 , wherein the first analog front end is configured to individually monitor the voltage of the first set of a plurality of battery cells.

3. The battery pack of claim 2 , wherein the processor is configured to

receive a plurality of voltage values for the first set of a plurality of battery cells from the first analog front end, and

passively balance the first set of a plurality of battery cells based on the plurality of the voltage values.

4. The battery pack of claim 1 , wherein the second analog front end is configured to individually monitor voltage of the second set of a plurality of battery cells.

5. The battery pack of claim 4 , wherein the processor is configured to

receive a plurality of voltage values for the second set of a plurality of battery cells from the second analog front end, and

passively balance the second set of battery cells based on the plurality of the voltage values.

6. The battery pack of claim 1 , wherein the series connection contacts are configured to receive a conductive blade contact of a first power tool to engage the series connection contacts, and the parallel connection contacts are configured to receive an insulating rib of the first power tool to disengage the parallel connection contacts.

7. The battery pack of claim 6 , wherein the first power tool operates at a first voltage level, and wherein the set of parallel connection contacts are configured to be in the normally closed state when connected to a second power tool operating at a second voltage level, the second voltage level being lower than the first voltage level.

8. A method for monitoring a battery pack comprising:

connecting a first set of plurality of battery cells in series;

connecting a second set of plurality of battery cells in series;

individually monitoring, using a first analog front end, each cell of the first set of plurality of battery cells;

individually monitoring, using a second analog front end, each cell of the second set of plurality of battery cells;

synchronizing, using an electronic processor, monitoring by the first analog front end and the second analog front end;

disengaging, with an insulating rib of a power tool, parallel connection contacts operable to connect the first set of plurality of battery cells and the second set of plurality of battery cells in parallel, the power tool being external to the battery pack; and

engaging, with conducting blades of the power tool, series connection contacts to connect the first set of plurality of battery cells and the second set of plurality of battery cells in series.

9. The method of claim 8 , wherein individually monitoring each cell of the first set of plurality of battery cells further comprises individually monitoring voltage of each cell of the first set of plurality of battery cells.

10. The method of claim 9 , further comprising:

receiving, at the electronic processor, a plurality of voltage values for the first set of the plurality of battery cells from the first analog front end, and

passively balancing, using the electronic processor, the first set of the plurality of battery cells based on the plurality of the voltage values.

11. The method of claim 8 , wherein individually monitoring each cell of the second set of plurality of battery cells further comprises individually monitoring voltage of each cell of the second set of plurality of battery cells.

12. The method of claim 11 , further comprising:

receiving, at the electronic processor, a plurality of voltage values for the second set of the plurality of battery cells from the second analog front end, and

passively balancing, using the electronic processor, the second set of the plurality of battery cells based on the plurality of the voltage values.

13. The method of claim 8 , wherein disengaging the parallel connection contacts occurs before engaging the series connection contacts.

14. The method of claim 8 , further comprising:

disengaging the series connection contacts; and

engaging the parallel connection contacts.

15. The method of claim 14 , wherein disengaging the series connection contacts occurs before engaging the parallel connection contacts.

16. The method of claim 8 , wherein disengaging includes disengaging normally closed parallel connection contacts and wherein engaging includes engaging normally open series connection contacts.