I have a Vruzend kit that I got to check them out. The V1 kit uses the stainless steel connector as the leaf spring to apply compression onto the cell tip, and also the conductor, so....this kit is for low current, 2A at most and 1A continuous per cell. These are new-in-box, but technically they are "used".
After experiments, I have 146 unused caps left, enough to build a pack out of 73 cells. If you are using the common recycled laptop cells, the low current of those cells and these connectors is a fair match. Such a pack is not likely to work for an ebike, as the low powered kits still require 20A minimum, and for a common 5P, that would be 4A from each cell. So...what would they be good for?
I going to suggest a 12V powerbank using 4S. Our common 18650 cells don't work well for 12V because 3S would mean the cells are overcharged if you use the 12V utility socket from a car (13.8V alternator). So 3S would be dangerous. 4S would mean that you are giving up half the Amp-hours the cells could be charged to. With a 3.0V LVC and a 4.2V max charge, the 13.8V alternator in a car would charge a 4S pack to 3.4V.
What good is that? If you have a 12V adapter for charging your laptop, they can take-in up to 15V as a safety margin to handle voltage spikes from high-performance alternators, and 4 X 3.7V = 14.8V__That's not great, but...at least you'd get more Ah from the pack, and the cells would still not be in any danger of overcharging.
The second option I find interesting for a low-amp pack is a 7S / 24V system. This is one area where 18650 cells are actually very good for it. 3.0V LVC for 7S is 21.0V, and fully charged to 4.2V per cell is 29.4V
21V - 29V is perfect for existing 24V inverters, DC/DC converters, and solar panels. You will get the full range of Amp-hours from your cells. If you don't have any other Vruzend caps to add to this, 73 cells will make a 7S / 10P pack, with three caps left over. If using used 2200-mAh laptop cells, such a pack would be a hair over 20-Ah @ 24V
https://endless-sphere.com/forums/viewt ... 4#p1276959
Regardless, I don't need them anymore, and I only need the buyer to pay shipping. This includes the nut-driver (its an odd size, 5.5mm) and the cap nuts, plus the bus bars.