A bad ground wire can drain your battery indirectly through creating a parasitic drain.
A parasitic drain means that even when your car is off, a small amount of current can still flow through the cables due to a bad connection.
This can lead to a slow discharge of the battery over time.
The bad ground can contribute to other electronics also drawing more power than it needs due to a poor grounding connection.
A bad ground wire can also sometimes reduce the charging of the battery from the alternator or make it hard to start the car.
Other symptoms of a bad ground on your battery or car are intermittent electrical issues, flickering lights, difficulty in starting the vehicle or unusual electrical noises.
A bad ground wire or corroded or loose ground wire also creates higher resistance which can damage electronics, your ignition control module etc.
The black wire on a car battery is the ground also known as the negative with the --- Symbol.
The red wire on the battery is the positive wire which has the + symbol.
The red wire for a car or truck or automotive battery goes to the positive side of the battery which is + and the back wire always goes to the negative side of the battery which is the ---- symbol.
If you connect the battery cables wrong the battery will spark and can catch fire and it can ruin your electronics in your car.
Also make sure that the battery cables are tightened down enough to make contact and prevent starting problems and charging problems.
And make sure the battery cable ends and battery terminals are also clean and free of corrosion.
You can clean battery terminals of the corrosion by mixing some baking soda with some water and then poor it on the battery cables and allow it to sit for awhile.
Then brush the battery terminals until clean.
You can also dip the battery cables ends into some baking soda and water and allow it to sit and then brush off the battery cable ends and rinse with a bit of water.
When your battery cable ends and battery terminals are corroded it can prevent the current from flowing through the battery cables and prevent the battery from charging properly are cause a clicking sound when you try to start the engine.
If loose enough the engine may not want to start at all.