Using 21700 cells good for 70A a pop at 5000mAh this is quite a pack. To save weight I made a 20s5p pack, still good for 350A and 25Ah (almost 2kWh) and at half the weight of the previous motorcycle pack. To make sure not to get excess voltage sag in the pack I made the usual CU/NI sandwich with a 0.2mm cupper sheet and a 0.2mm nickel strip on top.

I replaced the tips on the spotwelder and man did that make a difference! Now all the welds are flawless and I’m confident this battery will deliver enough to keep us flying.

Since this pack is not going into any frame or box I made a 3D-printed box for it. I also added the connector to the box instead of having wires protruding. Looks great in comparison! To do the pre-charge of the controller I added an extension cord with a resistor built in. This way you can do the pre-charge, remove the resistor part and connect the battery pack directly to the controller. A lot neater and less wires to manage.

Right now the battery is charging for the first time. Quite nerve wrecking but it usually goes well. Next step is to mount the battery on the paramotor and do a full cycle test.. Full throttle for an entire battery.. If it survives that without limiting power due to heat – well, then we’re good to go. If it doesn’t I don’t quite know what to do, but we’ll figure it out..