Im starting a new DPV battery replacement project. In fact Im building 5 packs including replacements for 400 ,550, and 650 Cudas.
A few years ago I built a 96 cell Li Ion pack for my Cuda 550 using Samsung 2600mah 18650 cells.
This time around I am using 84 Panasonic 3350mah 18650's.
This will give me 84 * 3.7 *3.350 = 1041wh of power.
The reason I went for 84 cells is based on the layout of the cells.
I am using the plastic 18650 spacers to build the holder that creates a tidy row and column layout as opposed to a hexagonal lay out that would allow a few more cells squeezed in. It allows for a much tidier and easier build.
Im still awaiting the cells but it looks like I can just still use the stock battery case lid and retaining system. The 400 will be only just high enough while the 550/650 packs leave quite a bit of height using the stock case parts that I can easily add more lead to the pack to make it weight the same as the stock pack.
The 400 pack is the same as the 550/650 except for the height and the way it is held in place.
With the 550/650 there is a radial support in the nose cone that the battery sits against. With the 400 there is a pin in the centre of the cone that supports the pack.
Plastic holders for 18650's. 42 cells per level.
Well, the cells finally arrived! All 420 of them!
Several hours of tab welding later I have 2 finished rows of cells.
I you are t building your own pack based on this build take careful note of the layout of the cells and of the routing of the nickle plate in the photo below.
Both upper and lower level are laid out the same. But the top and the bottom of each pack has the nickel plate welded in a different configuration as shown.
The bottom left is the bottom row of cells and the bottom right is the top row of cells.
This photo below shows the connection points for the BSM
0 is 0 volt or negative, From there the voltage rises by 3.7volt nominal.
6 is the half way point. Its not clearly shown but this tab is soldered to the bottom of cell 5.
1`2 is of course the positive of the pack and sits at 44.4 volt nominal (50.4 volt full charge).
EDIT: bottom right cell on top left pack is upside down.
And the assembled pack nearing completion.
This was only just high enough to hold the 2 rows of cells and still fit in a Cuda 400.Unfortunately for it to work the threaded rod had to protrude through the lid.
This will be sealed up on completion.
The pack weighs in at 1.5kgs less than the stock NiMh 400wh pack. So next job is to make up a weight for in front of the battery pack. While I would like to offset the weight to help with trim, Im not sure this will be possible. But it does give the option of mounting heavy gear on the scooter and removing internal ballast. Perhaps even mounting external ballast at the bast to help compensate for heavy camera gear?
I have managed a burn test and recharge. I had some issues with the watt meter so couldnt get a total watt Hour reading from it but I manage to calculate it out based on 15 minute volt and amp readings.
1007wh on first discharge and 1052wh on first full charge.
| Time | Volts | Amp | Amphour | Watt | Watt hour | |
| 0 | 49.4 | 8.35 | 412.49 | |||
| 15 | 47.6 | 8.06 | 2.015 | 383.656 | 95.914 | 95.914 |
| 30 | 46.3 | 7.8 | 1.95 | 361.14 | 90.285 | 186.199 |
| 45 | 46.5 | 7.8 | 1.95 | 362.7 | 90.675 | 276.874 |
| 60 | 45.3 | 7.7 | 1.925 | 348.81 | 87.2025 | 364.0765 |
| 75 | 44.4 | 7.6 | 1.9 | 337.44 | 84.36 | 448.4365 |
| 90 | 43.5 | 7.3 | 1.825 | 317.55 | 79.3875 | 527.824 |
| 105 | 42.8 | 7.2 | 1.8 | 308.16 | 77.04 | 604.864 |
| 120 | 42.2 | 7.2 | 1.8 | 303.84 | 75.96 | 680.824 |
| 135 | 41.6 | 7.2 | 1.8 | 299.52 | 74.88 | 755.704 |
| 150 | 40.9 | 7 | 1.75 | 286.3 | 71.575 | 827.279 |
| 180 | 40 | 6.7 | 1.675 | 268 | 67 | 894.279 |
| 195 | 38.2 | 6.6 | 1.65 | 252.12 | 63.03 | 957.309 |
| 210 | 34.3 | 5.8 | 1.45 | 198.94 | 49.735 | 1007.044 |
| 23.49 | 1007.044 | |||||
| Recharge | 23.7 | 1052 |
3000wh pack anyone? Should fit in a Cuda 850!
