Well the flat of the battery is the negative side.
see the signs on the ends. "-" means negative and "+" means positive.
If you have a post battery(the cable attaches from the top) the positive post is larger than the negative.
I assume you're asking how can you tell which is positive and which is negative? The red cable is positive in the black cable is negative. But if they are not color-coded the positive battery post is slightly larger than the negative battery post. If you try to connect the negative cable to the positive post it would be a tight fit and if you connect the positive cable to the negative post it would be loose.
positive to positive
Positive to positive, negative to negative if you are asking about installing one battery in a vehicle.
negative to positive,electrons to protons
What happens when you inadvertently crossed the positive battery terminal from a negative to a positive and a positive to a negative.?Read more: What_happens_when_you_inadvertanly_crossed_the_positive_battery_terminal_from_a_negative_to_a_positive_and_a_positive_to_a_negative.
It is almost always imprinted on the battery next to the posts. If not the positive + post is slightly larger than the negative - post.
Connect a battery charger to battery positive to positive negative to negative
The positive end of a battery goes to the positive end of the terminal. In retro spec, the negative end of a battery goes to the negative end of the terminal.
The positive battery cable will be going from the positive terminal of the battery over to the starter solenoid. The negative battery cable goes from the negative battery post to either a bolt on the generator upper bracket or the side of the engine block. Typically, the positive cable is red, and the negative is black, but people do all sorts of odd things to their cars, like have the wrong colored battery cables, so, go by how they are routed, not by what they look like.
red is positive on a negative ground system
There are 2 battery terminals. A positive or hot and a negative or ground. The positive is slightly larger than the negative.