FRITZ!Fon C4 Service - Knowledge Base

FRITZ!Fon C4 Service
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Battery only holds a charge for up to one day (standby time)

When its battery is fully charged, FRITZ!Fon can only hold a charge for up to one day when it is not left in its charging cradle. After that, the telephone must be placed in the charging cradle again or it turns off.

Simply proceed as described below. After each measure, check whether the issue persists.

1 Installing the latest software for your telephone

2 Recharging the telephone battery

  • Fully charge the telephone battery. Leave the telephone in the charging cradle for at least 12 hours.

3 Activating the power saving mode for battery operation

  1. Press the "Menu" key on the telephone.
  2. Scroll to "Settings" and press "OK".
  3. "Display" > "Power save"
  4. Enable the option "for battery operation".

4 Replacing the rechargeable battery

If the issue persists despite trying all of the measures in this document, then the rechargeable battery is defective. Therefore, replace the battery:

Within the first 12 months after purchasing FRITZ!Fon, we will send you a replacement battery free of charge if you send us the defective battery along with a copy of your proof of purchase (with sufficient postage) to the following address:

Important:AVM will not be liable for any damages that arise during transport. Therefore, send the battery in a padded envelope, for example.

AVM Customer-Service
Alt-Moabit 95
10559 Berlin

After the first 12 months have elapsed, you can purchase a new rechargeable battery from specialized vendors or order one for 9.90 € plus postage from us; simply send an e-mail to or call us at +49 (0)30 39 00 44 15 (Mon - Fri 9:00-17:00).

Note:Batteries constitute expendable material, which is not covered by the warranty (see also the warranty conditions in your manual).