The white stuff on your battery terminals is usually caused by a battery not being charged enough or not getting enough charge.
The white stuff especially if it's powdery is a result of sulfation.
It could be that your cars battery is not getting enough charge through the alternator or your battery is going bad.
Also to get a good charge in your battery you need good clean battery terminal connections so make sure to clean those battery terminals off and make sure the battery cable connections are tight as well.
You can use baking soda and warm water mixed together to clean the white stuff off your battery terminals and you can also clean all types of battery terminal corrosion off batteries using baking soda and water.
To clean off blue battery corrosion mix some baking soda with some warm water.
Then stir the baking soda and water together to mix it up.
Next pour the baking soda and warm water solution onto the battery terminals and allow the baking soda and water mixture to sit for around 5 to 10 minutes.
Then use a wire brush to brush off the corrosion and use a water hose to wash the baking soda and blue corrosion away.
Then pull the battery terminals off and clean them with a battery terminal brush and dip them in baking soda and water too.
Corroded batteries are not dangerous but you should still avoid touching the battery corrosion with your bare hands.
If you need to clean battery corrosion you should wear gloves and use some baking soda and warm water to clean the battery corrosion off.
When your cars battery has corrosion you can mix some baking soda and warm water together and then pour the baking soda and water mixture onto the corrosion on the car battery.
Allow it to work for around 5 to 10 minutes.
Then use a wire brush to help brush off the battery corrosion and then use a hose to wash the corrosion away.
Battery corrosion can make a battery seem like it's dead because it can prevent charging of the battery through the alternator and also make a bad contact where the starter may or may not engage.