It is important to us that you have maximum flight time. To achieve this, we must look at the elements necessary to send power to your aircraft. One criteria often overlooked is how power is transported from cell to cell. It is industry standard to interconnect battery cells with weld tabs. This is generally done using a 7mm wide, .2mm or so nickel plated strip. While generally effective for low current batteries, this is unacceptable for high current applications as the material has too much resistance between cells. Early on, we realized nickel wouldn't work for our high power batteries and looked to utilizing more conductive materials. Copper is 4x as conductive than nickel is, but there is a real complexity to welding it. Generally speaking, most welding is done using a capacitive discharge welder. These exist in many forms often found online. This practice relies on the resistance between the nickel weld tab and the cold rolled steel battery cell to generate enough heat to create a weld when the effective capacitor creates a short circuit between two probes on the weld area.
There are techniques to try to use copper, nickel plated sandwiching, doubling up on nickel. We have tried all of these and we've found that nickel plated sandwiching results in weak welding, and doubling up on nickel will never yield the results of copper, it's not possible to weld .2mm x 4 layers of nickel on a battery. Thus we had to invest in the proper equipment to weld copper, this being either a laser welder or an ultrasonic welder. Looking at the options, we found that a galvometric fiber laser would do the best job with our welding application. Thus, since January of 2023 we have utilized all copper welding using our galvometric laser, creating strong, highly conductive welds of up to .5mm of copper plate. You can see in the photo above a photo of the fiber laser creating welds for a Molicel P42A pack.