Husqvarna Automower 420 Workshop Manual page 33

3. Disconnect the battery cable/cables from the main
circuit board.
4. Remove all cables from the battery/batteries cable
holders.
1191 - 001 -
5. Remove the 4 screws for the battery holder.
6. Remove the battery holder.
7. Remove the battery from the battery holder.
8. Install a new original Husqvarna battery/batteries in
the battery holder.
9. Install in opposite sequence.
6.19.2 To replace the charging plates
If the battery of the product does not recharge this may
be because of worn or damaged charging plates. Also
do a check of the contact plates on the charging station.
Repair instructions - 33