Is Charging A Car Battery Dangerous. Why Is It Dangerous to Have a Corroded Battery. Charging it in your closed trunk is a little riskier but i still do it.

There is a write-up at the Battery University Website which talks about it. Why Is It Dangerous to Have a Corroded Battery. Automotive engineers design car systems to ensure that the battery remains charged throughout extensive use.
Set your battery charger based on your needs.
How long it will take for your car to charge the battery depends a lot on the car engine and the size of the car battery. This could result in a dangerous failure condition but more importantly under certain conditions explosive gases might be released from your battery while it is charging. The two primary risks are from hydrogen gas formed when the battery is being charged and the sulfuric acid in the battery fluid. However many workers may not see it that way since it is such a common activity in many workplaces.

