Lithium polymer cells of high amperage [16aH] from Hobby King are more economical when purchased during one of their sales but those modules sizes when added may not get a max voltage just under the controllers limit by less than one cell. I have opened up these modules and regrouped the cells to get as close as possible to the controllers max voltage limit. Of course this severing action voids the warranty so make sure you choose a fully working module for such reassembly knowing full well the warning label reads,
Never disassemble or modify the battery in any way. The max voltage of the Cyclone 3000 OEM controller at nominal 72v is 84v as warrantied by Luna Cycles. To get the number of cells needed to reach this voltage we divide 84v / 4.2v = 20.00 cells. Hobby King sells the 16 Ah series in 6s and 4s strings when on sale for about $72.00. You get the best deal [watt hrs. /$] when buying the 6s 16aH modules for repacking. You will have 3 - 6s 16aH modules and 1- 2s 16aH modules for the 20 cell pack which hooked in series equals the desired 84 v.
These are some tools & materials that make the opening and repacking of the module safer:
The tools & materials:
1. Scissor with curved blades and blunt tips -- used for removing the existing heat shrink. Do not use an X-Acto Knife because the likely hood of puncturing the aluminum foil pouch is somewhat higher than when using the scissor.
2. High Wattage soldering iron. Here we see a Weller 250 watt. This big gun will heat up the 10 gauge silicone output wires very quickly and heat the pouches less than a 40 watt one would.
3. The hot glue gun with strong high-temp low moisture glue sticks is for standby in case you nick a hole in the aluminum pouch. If sealed immediately the pouch hole will let little or no moisture entry and the band aided pouch is likely still usable. Mark this cell and occasionally monitor with a heat temp gauge -- see item 4
4. The Fluke Temp Gauge is for measuring the pouch temps. All this solder gun heat work when done quickly will not make the pouch over 100 F near the cell terminal batt tab attachments when room temp is 72 F. With an unsealed pin hole the cell will gain mositure and oxygen and is likely to keep getting hotter. Dispose any cells that do not revert to room temp soon -- 20 min?. MONITOR such fixes.
5. The soldering paste/fux will make for better solder gun heat conduction and lessen oxidation at the solder/metal surface so you will get a quicker terminal wire attaching job. Do not use plumbers flux shown here for circuit board work as it can contaminate some board metals.
6. Some solder absorbing braided wire maybe useful as sometime the OEM output terminals have an abundance of solder.
7. Solder of say of 0.075" diameter rosin core lead free for terminal wire attachment.
8. Not shown 2" Scotch tape for binding the pouches before adding heat shrink.
9. Heat shrink wrap to fit over the pouches in 2 different wrapping axes and an adjustable temp heat gun.
10. Look Carefully -- Most of these tools are sitting on white sheet of 0.012" thick Nomex paper which is used both as the OEM insulation of the battery terminals and for some of the cushioning. Put some of this paper over the extra terminals the pouches now have.
After removing the OEM heat shrink and cushioning material a 6s 16aH module will look as if it has 12 cells but these pouches are folded and there is actually on 6 pouches.
During this repacking I wanted several 3s packs so the magic marker line down the middle is where the cellophane tape is cut to get that separation. You will have to heat the copper battery tabs with the soldering gun using flux at the connecting junction of the pouches under this center line to separate them.
Reattaching the 10 ga wires to the battery terminals is the hardest soldering job on repacking the pouches so leave the 2 terminal wires attached to the battery tabs and disconnect one of the wires from the XT-90 plug which on this end is an easy re soldier.
The newly sized pouch is now ready for cushioning material, Nomex and the heat shrink materials are added.
And last add the JST 2.5 XH 4-Pin Connector Plug with Wires to the BMS wires from the battery. These plugs can be found on eBay or Amazon. You have to get the BMS wires in the right order. When the plug's aligning ridges are up the negative terminal is on the right end and the voltage of the wires gets higher going from right to left.