Mazda CX-30 2020 Owner's Manual page 552

If Trouble Arises
Battery Runs Out
Route the jumper leads away from parts that will be moving:
Connecting a jumper lead near or to moving parts (cooling fans, belts) is dangerous.
The lead could get caught when the engine starts and cause serious injury.
CAUTION
Use only a 12 V booster system. You can damage a 12 V starter, ignition system, and
other electrical parts beyond repair with a 24 V power supply (two 12 V batteries in
series or a 24 V motor generator set).
NOTE
Do not use vehicles with M Hybrid as a booster vehicle.
1. Move the booster vehicle so that its battery is as close as possible to your
vehicle's battery.
2. Make sure that the power such as for the headlights and air conditioner is turned
off.
3. Remove the battery cover.
4. Turn off the booster vehicle's engine and connect the jumper leads in the
following order.
Make sure that the jumper leads are securely connected so that they do not
disconnect due to engine vibrations.
1st lead
Positive (+) terminal on the discharged battery
Positive (+) terminal on booster vehicle's battery
2nd lead
Negative (-) terminal on booster vehicle's battery
7-40