TomTom ONE - Traffic Information; RDS-TMC Traffic Service; Using Traffic Information

Chapter 18
Battery notes
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Battery notes
We recommend that you fully charge your TomTom ONE the first time that you
connect it to your computer. It takes about 2 hours to charge the battery
completely.
Note: Your TomTom ONE uses a small amount of battery power to maintain
its state when you switch it off. If you do not charge it for a prolonged period
of time then you will lose this state and your TomTom ONE will re-start. Your
settings will however, be maintained.