title_body: How to charge LiPo batteries in series? Is there any way to use my main charger, which can charge 2-6s batteries, to safely charge multiple 1s batteries in series? (assuming all of the batteries are the same capacity)
  
  How would I go about doing this?
upvoted_answer: Huh. I never thought about this before, but charging identical LiPo batteries in series with one another seems logical enough. In fact, here's an article which discusses how to do it, which I'll summarize here.
  
  Prerequisite requirements:
  
  
  The charger must support the series battery (e.g. for 2x 4s batteries, the charger must work with at least 8s)
  You must create a balance lead adapter (and separate main discharge lead adapter) that combines the leads from the batteries into one. The highest voltage cell on one battery will have the same balance connector pin as the ground wire in the next battery's balance lead. (graphic below shows this in more detail)
  All batteries MUST be the same capacity, but not necessarily the same cell count. (e.g. not 1s 1000 mAh and 1s 1500 mAh, but 1s 1000 mAh and 4s 1000 mAh is fine)
  All batteries MUST have per-cell voltages that are close to one another. A difference of 0.05 V is usually okay.
  
  
  
  
  
  
  Advantages
  
  
  Time savings from charging all at once and hooking up batteries fewer times
  Can allow for faster batch charging than parallel charging if the charger's power limit is less of a bottleneck than the current limit
  Unlike parallel charging, each individual cell is monitored and balanced separately by the charger
  
  
  Disadvantages/Risks
  
  
  If something were to go wrong during the charge cycle it would effect multiple packs. (e.g. an internal cell short in one pack could light all packs on fire)
  All batteries MUST be properly connected to both the main discharge lead adapter and balance connector adapter, (and connected in the right order) or funky stuff like short circuits and fires could happen!
  Can be a slower batch charging method than parallel charging if the charger's power limit is more of a bottleneck than the current limit