Mazda Mazda3 2019 Owner's Manual page 479

Location shown in the figure (do not connect to the negative (-) terminal of the
battery)
5. Start the booster vehicle's engine and rev the engine.
6. Start the engine of your vehicle. Run the engines for about 3 minutes to temporarily
charge the battery of your vehicle.
7. Disconnect the jumper leads in the reverse order of their connection.
8. Install the battery cover.
9. Have your vehicle inspected by an expert repairer, we recommend an Authorised Mazda
Repairer as soon as possible.
If Trouble Arises
Battery Runs Out
7-15