For me my mind will drift off and I won't be able to stay focussed on completing repetitive tasks.
As a result thoughts of failure, stress, frustration, distraction etc will kick in and I will actively start avoiding it and sabotaging completing it until the last minute.
It only makes sense for me to try and avoid that scenario so I would say yes I have a fear of repetitive boring work/tasks but I don't think its a phobia in the strict sense.
Or you could just use all of the space for a sodium battery and fully charge it as it won't need long term storage in that state.