What year is it? I know in my 96 civic. When i first got it the fuse that makes the speedo work, and turns the alt. on to charge the car was blown. Caused my speedo to randomly jump. Replaced the fuse, never had a problem with it after that. While it was blown..the car would still run, but barely charge the battery enough that it would keep running. After i replaced 3 batteries, all the power/ground wires to bigger wire, and an altenator, i found out it was a fuse...300 bucks later.