Extermal Battery Pack.
Posted: Tue May 12, 2009 12:59 am
OK, tonight's project was to work out what makes the external battery pack tick.
So using brute force I opened up one of them up.
Once open I discovered that there are two screws hidden under the labels that would allow the pack to be opened without destroying it. Here is probably the place to mention that, lithium is toxic so take care not to damage any cells.
My pack comprised of 4 3.7V Panasonic Lithium Ion Prismatic Cells wired as follow:
-VE -VE +VE +VE
+-----+ +-----+ +-----+ +-----+
| | | | | | | |
| C1 | | C2 | | C3 | | C4 |
| | | | | | | |
+-----+ +-----+ +-----+ +-----+
+VE +VE -VE -VE
C1 and C2 -Ve terminals are wired together and connected to the -VE terminal on the controller board. C3 and C4 +VE terminals are wired together and connected to the +VE terminal of the controller board. Now all the bottom terminals are all wired together and wired to the UM connection.
This works as follows C1 and C2 are wired in parallel to make a single larger 3.7V Cell and C3 and C4 are wired to make a second large cell. Now the two 'larger' cells are wired in series to make a single 7.4V cell.
With this knowledge it should be possible to make your own replacement pack. It looks like the cells are Panasonic ones similar to these.
http://www.panasonic.com/industrial/bat ... 03450A.pdf and can be had for $13 each here:
http://www.sabahoceanic.com/epages/saba ... s/14058004
Dave.
So using brute force I opened up one of them up.
Once open I discovered that there are two screws hidden under the labels that would allow the pack to be opened without destroying it. Here is probably the place to mention that, lithium is toxic so take care not to damage any cells.
My pack comprised of 4 3.7V Panasonic Lithium Ion Prismatic Cells wired as follow:
-VE -VE +VE +VE
+-----+ +-----+ +-----+ +-----+
| | | | | | | |
| C1 | | C2 | | C3 | | C4 |
| | | | | | | |
+-----+ +-----+ +-----+ +-----+
+VE +VE -VE -VE
C1 and C2 -Ve terminals are wired together and connected to the -VE terminal on the controller board. C3 and C4 +VE terminals are wired together and connected to the +VE terminal of the controller board. Now all the bottom terminals are all wired together and wired to the UM connection.
This works as follows C1 and C2 are wired in parallel to make a single larger 3.7V Cell and C3 and C4 are wired to make a second large cell. Now the two 'larger' cells are wired in series to make a single 7.4V cell.
With this knowledge it should be possible to make your own replacement pack. It looks like the cells are Panasonic ones similar to these.
http://www.panasonic.com/industrial/bat ... 03450A.pdf and can be had for $13 each here:
http://www.sabahoceanic.com/epages/saba ... s/14058004
Dave.