Remove the 2 screws to open the cover on the battery box. Lift off the cover and take a picture or make a drawing of how the wires are connected. Remove your old batteries from the case. Place the two new batteries in the box the same way. (maybe use some foam or tape to prevent rattling).
The long wire harness goes on first. Just plug the black wire into one black connector and the red into the red terminal on the other battery.
Make sure you are plugging it into the battery terminals in the side opposite from the main wires coming out of the casing, best to place the battery casing as shown in the picture with the wires coming out on the right to avoid confusion.
Using the included bolt, attach the short red wire with the round connector to the red wire with the round connector coming out of the battery pack.
Plug in the existing short wire with the temperature sensor into the red charging plug. (Its a good idea to tape this to the top of the battery, you can use it without as well if yours is broken or if you have lost it)
Repeat the same with the black round connector going to the blue wire in the case.
The cover for the main battery case needs to be notched on the bottom to allow the long harness to come out.
A knife, file or pliers can be used for this. I recomend putting some weather stripping foam on top of the batteries and wiring to avoid rattling sound.
Plug the shorter harness into the rear battery.
We recommend a sturdy rack like the original eBike rack or one of our Multi racks and a soft trunk bag to place the battery on the back of the bike.
Feed the long harness through the main battery compartment on the bike out the back accessory storage door and insert the battery. Bring it up to the rear battery and plug it together, matching red to red and black to black.
Remember that your bike will not run or charge if the two packs are not plugged together. You can charge them on or off the bike, as long as they are connected to each other.
Charge your batteries over night and take it for a spin.