Amazon.com: Replacement Battery compatible with Braun Oral-b Triumph Professional Care Toothbrush, 42 mm L X 17 mm D : Health & Household
Amazon.com: FITHOOD Replacement Battery for Oral-B 3738 Triumph 9000 Professional Care 8000 Professional Care 8300 Professional Care 8500 Professional Care 9500 Triumph 4000 : Health & Household
Braun Oral-B Triumph 9900 Repair - iFixit
Braun Oral-B Professional Care 9900 Triumph Ni-MH battery Replacement - iFixit Repair Guide