A while back, Joshua Bardwell came to us with a need for an improved parallel board that allowed him to charge more batteries than he was currently able to. However, as with the majority of most multirotor and drone pilots, he only needed 4S capability. A few drawings were sketched up to make the most of the available space, samples were made, testing ensued, and what we have today is the STRIX 4S Parallel Charging board that allows for up to 10 4s packs to be charged at once!
This board's main power lead comes equipped with an XT60 connector, which is handy for chargers like ISDT. It also comes with an adapter to go from XT60 back to traditional 4mm banana style. The included balance lead is 5 pin XH style and one tab may need to be trimmed to fit properly into the balance socket depending on your charger's needs.
Safety is a major concern for any form of parallel charging. Checking each cell of every single battery before connecting them together is extremely important! If you see a cell's voltage that is not like the rest, do not charge it with the others in parallel! To help with this, we have added a cell checker at the top of the board. You need to check them one at a time before plugging them all into the board, however. We have also provided replaceable fuses between the main power leads to aid in preventing surges from one pack to another. We suggest only parallel charging packs that are within roughly 0.1 volts per cell, or 0.4 volts for a 4S pack. So a pack that is at 15.0 volts total would be safe to charge with another pack that was 15.4 volts or 14.6 volts.
Do your batteries have short balance leads? Try these 4s balance tap extensions!
Please watch these videos from Joshua for proper parallel charging techniques: