Installing a 7th Cell on a 6-Cell Stick Pack
Battery cells - (2) 1.2 volt Sub-C cells. If youre currently using budget sport packs then buying inexpensive individual cells will work just fine. If you will be building multiple 7-cell packs from sport packs, you can disassemble one of the sport packs for the individual cells. If you are running high performance matched packs then try to find cells that are matched closely to the numbers that your current cells are capable of.
Tools needed - Needle nose pliers, wire cutters, small flat head screwdriver, wire stripper, hobby knife and a soldering iron 60 to 80 watts works best, (Hotter irons heat things up more quickly). This will allow the solder to join together faster keeping prolonged heat from damaging the cells.
Accessories needed: 60/40 solder, a small tube of soldering flux, 2-battery bars and adhesive such as Pro Bond, E6000, Zap or equivalent glue, and some rubber bands for holding the cells together after gluing them.
Step One - Cut off the heat shrink at the end of the battery (same end as the plug) along with the plastic end cap. This should expose the terminals of the end cells along with the wire joints.
Step Two - Disconnect the wires from the positive and the negative terminals of the cells with your soldering iron.
Step Three - Scuff the ends of the individual cells with a fine grade sandpaper.
Now, tin the terminals of the cell and the ends of the battery bar using your soldering iron, solder and flux.
Now were going to solder a battery bar to the inside cell of each pack. See figure B. These will be joined to the extra cell.
Note: The battery bar will need to be soldered at an angle of approx. 110 degrees to position the seventh cell out of the way of the battery hold down in the E-Maxx.
Tip: (To help get oriented with where the cells need to be placed. Lay both packs down flat on the table side by side, as if they were sitting in the E-Maxx with the exposed terminals pointing toward the rear of the truck. The seventh cells will need to be positioned on the top inside corner of the pack above the exposed cells.)
Once the battery bar is attached to the pack solder the individual cell onto the open end of the battery bar.
The battery trays in the chassis of the E-Maxx can be used along with the hold downs to make sure that the seventh cell is in the correct position. If the cell needs to be moved then detach and re-solder. Also make sure that the terminals that are being connected are of opposite polarity (negative to positive positive to negative) See figure B above. Now that the extra cell is attached to the battery bar it will be much easier to glue the cell to the pack.
Step Five - Apply a small amount of glue between the cell and the pack. Place a rubber band around the cell and pack to hold the cell down onto the pack. Now place the pack in the E-Maxx and secure the battery hold downs. This will keep the cell in the proper position while the glue cures.
Remember to only use a small amount of glue between the cells so that you dont end up gluing the cell to the battery hold down. Allow the glue to set-up overnight before handling the cells.
Step Six - Now its time to solder on the plug wires. The wires need to be positioned as shown in figure-C to clear the battery hold downs and the transmission cover. The positive and negative terminals on your packs may not be whats shown, but its OK as long as youve made all of your connections positive to negative.
Solder the black wire to the negative terminal and the red wire to the positive terminal of the assembled pack. Now your pack is complete and ready for action.
You have just now transformed your pre-assembled 6-cell pack into a high-voltage 7-cell pack (8.4 volts). Combining both of the 7-cell packs with the twin Twin Titan/EVX power system will take your E-Maxx to even higher levels of performance for power climbing, competitive racing and top speeds of over 30 mph.
? Warning -
take extra caution not to get the electronics onboard the truck wet. The extra voltage of the 14-cell power system combined with moisture can cause big problems, damaging not only the esc but also the batteries. Water and/or moisture damage is not covered under the ESC warranty