They are essentially the same battery in a different form factor. Other than the physical architecture, there's no reason why you shouldn't be able to use TB50 chargers to charge TB55 batteries. As long as the battery physically fits in the case, it should work. As an example, I use my M600 battery charger to charge my Inspire 1 batteries.
Since you have not included any photos or data that is the best answer I can give.
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