Canon Legria mini X Instruction Manual page 282

Do's and Don'ts
Built-in Rechargeable Lithium Battery
The camcorder has a built-in rechargeable lithium battery to
keep the date/time and other settings. The built-in lithium battery
is recharged while you use the camcorder; however, it will dis-
charge completely if you do not use the camcorder for about
3 months.
To recharge the built-in lithium battery: Connect the compact
power adapter to the camcorder and leave it connected with the
camcorder off. The built-in lithium battery will be fully charged
after about 24 hours.
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