Well if the battery worked OK on another engine with a similar load, then it's probably OK. Is the 3500 kV (jet) motor a similar size (in watts or Amps) to the 1400 kV airplane motor? The kV of a motor does not really tell as much as the amps or watts used by the motor/prop combination.

If there are no obvious breaks in your solder job, then I would not redo it.