I love my PSII controller - only thing I’ve bought since starting all this rocketry stuff back up that’s been a better value was my Oddl Rockets Adeptor (it was only a couple bucks). Since I didn’t want to deal with LiPo batteries - I don’t do R/C aircraft or vehicles of any kind and have no interest in them - I went with straight replacement rechargeable NiMH C cell batteries from Amazon and a simple rack style charger from our local supplier of cheap tools from the exotic Far East, Harbor Freight. NiMH batteries, per the really involved article I found on a rather scholarly website about battery technology, like to be topped up after use so I don’t know how many total launches to failure you could get but I’ve never had the batteries die during a launch session. My success rate with Estes ignitors is well over 95% - I stopped tracking misfires after a few months of using my PSII controller with the NiMHs. I know a LiPo would produce more juice than what I’m using, the NiMHs are good enough so I don’t plan on swapping.