I have a Venom Stronghold charger I use when at the track (12V DC Input up to 25A Charge) and run off a 13.8V 20A Power supply. My 1/8 Pan Car runs a single 6s Lipo which uses an EC5 connector, after a crash taking my car out for the meet, I didn't want to leave my 6s packs fully charged so went to hook them up to discharge them down to storage levels. (These packs were not damaged as they were not in the car when I crashed)

On connecting to the charger (via a charge adapter board) I noticed a significant spark when plugging the pack in (although it was within the housing) which startled me a tad. Is this normal? I expect a spark when plugging into the ESC (charging the caps etc) but not when into the charger although I am not that experienced with 6s packs. Should I have turned the charger off first (Difference between 22.2v at the pack and 12v on the charger at the time?) or should I have plugged balanced leads in first?

I get a similar spark from time to time when plugging my 6s packs in. While it does startle a bit, I don't believe there's any cause for alarm... My packs have been doing it for a while w no problems.

No-Spark Hi Current Battery Arming Switch with Dean's Ultra Connectors- Safely Arm & Disarm your RC

I use this with my RC Aircraft with multi lipo's packs. Does its job of sparking connection of battery. Anything over 4's lipos you'll find sparking. That my experience with it.