This tutorial shows you step by how to solder up the FlatRack in a 2S2P configuration. In case you haven't read the Q&A section on this, 2S2P means 2 cells in series and two in parallel. With the AAA Cells the first 2 in series will give you 3.7x2 = 7.4 volts and the second set in parallel does not affect voltage, but doubles your current allowing better performance and more run time.
Step 1
Accidents happen, so put your Safety Glasses on now.
Wow, that was close!
Step 2
Grab your SuperFlex 18 Wire and a tape measure and cut off three sections as shown to 1.75" each. You will need a red, and two blacks.
Step 3
Now cut off three sections as shown to 2.75" each. You will need a red, and two blacks.
Step 4
This is the wiring you will need.
Step 5
Strip the wires with, you guessed it, your handy Wire Strippers.
Step 6
Grab your Helping Hands and tin the wires.
Step 7
Tin the Micro Plugs as well.
Step 8
Solder the black wire onto the side with the protruding pin.
Step 9
Slide the heat shrink on.
Step 10
Heat it with your lighter, be careful not to apply too much heat, you can burn the shrink if you do.
Step 11
Tin the terminals on the FlatRack AAA Battery Tray
Step 12
Solder the short red and black wires on the outside as shown.
Step 13
Bend them over like so.
Step 14
Solder the harness you made earlier.
Step 15
Install the short jumper on the other end.
Step 16
Install the long jumper as shown.
Step 17
This is what your wiring should look like when completed.
Isn't she sexy?
Step 18
Since we have 2 cells in series and 2 in parallel, we will check each set independently to confirm everything is cool. First we test the inside set and all is well.
Step 19
Next we test the outside set, and everything is good here as well.
Step 20
New we test them all together and get the same voltage since the 2 sets are in parallel. If all 4 cells were in series we would have gotten double the voltage here.
Step 21
This orientation is simple, just look at the left hand side and put the positive ends towards the red jumper and the negative towards the black jumper
Warning! If you have a brain fart and get it wrong, you can fry batteries, chargers and garages, so pay attention!
Step 22
This is what makes this such a nice solution, most battery holders will not make contact with the flat top cells that are used on the Lithium batteries.
Step 23
To charge the cells with our Lithium 7.4V, 500 mAh Charger you just plug it in.
Step 24
A final tip, to remove the cells use a screwdriver as the holder holds them very tightly. You may even want to bend the tabs out a bit so they don't grip so tightly.
Try not to damage the shrink and don't use cells without shrink as they will short against each other.
Note
That's about all there is to this one, its a very simple and easy way to charge the cells in a 2S2P which allows you to use our Lithium 7.4V, 500 mAh Charger or any 7.4 volt Lithium charger.