Originally Posted by neweuser

Well, in your first post, I would do option one. And an 8xl will give you better run time on 4s than a 7xl. The 9xl would do fine, just gear it up. 9xl is better on 5s though for more speed. the 989 can do two packs at once in series. This would be your best route. More money yes, but your frustration would soon end in all. Plus you would still have your Ice if needed to charge individual packs. Also, I would say a 10K would take more than 1.5 hours! more like 1 / 45min to 2. Like CHC said, the charge will slow as you get closer to the max voltage. With a 10k, that would be a lot.
the Neu would do great, but you need a controller that can do the 4 pole. Although, not sure how it would do on 4s???