Currently the best deal on these that I know of is here: https://www.aliexpress.com/item/New-6-String-2-7V-100F-500F-100F-120F-220F-360F-400F-500F-Super-Capacitor-Balancing/32818573262.html?
These are the boards I am using to balance the super capacitors in my SOLN1-2000 type projects. These boards have the positive and negative separated one to each side of the board. You can also add more solder for less resistance.
Works great with these capacitors: http://www.mouser.com/Search/ProductDetail.aspx?R=XV3560-2R7407-Rvirtualkey50450000virtualkey504-XV3560-2R7407-R
- Max voltage 6 caps 2.7V each in series: 16V
- Max charging current: (check capacitor specs)
- Max discharging current: (check capacitor specs)
- Equalizing current: ≤1A
- DC resistance: ≤8mΩ
- Red balancing LED light
- Size: 240 x 40mm