how do I know which one is positive (no plus sign on battery)?

if a round post terminal battery-then positive is the largest of the two terminal posts.

k
August 2009

easy to check ..all you need is a multi meter a digital on set to dc volts and it should read 12 to 13 volts. if you reverse polarity the leads on the meter red to black for example it will say 13v and a minus symbol will appear if its correct no symbol means red is on the correct post , if its Not a digital meter! the needle will go backwards ;)

Boaby
August 2009