That depends on the type of TrueTrainer model:
Model 2022 (TrueTrainer Base, Shift en Max):
Yes, you can train without connecting the battery charger to your TrueTrainer, but we recommend to use the battery charger for every training. Depending on the type and intensity of your training, the TrueTrainer will use more or less power. You will get a warning when the battery is low, but if this occurs during a workout, you do not want to have to get off the bike and find the charger. To prevent having to interrupt your training, please connect the charger at all times.
Model 2023 (Truetrainer 4.2 en 6.2):
No, the newer models do no contain a battery. In order to use the trainer, please make sure the trainer is plugged in.