alternator or battery?

Hi,

don't know much about cars, except that mine is not running properly.

I have a 98 ZX2...yesterday as I was driving my battery light was flashing. When I was stopped at light it would turn off, and the more i accelerated the more constant and bright it was. I went home and my grandfather and I popped open the hood and noticed corrosion at one of the terminals, so we cleaned it off, checked the connections, etc. My grandfather tested the battery and said it was "holding a charge"..he showed it to me and it read 13.9 or somewhere close to that i believe...he had me rev my engine and whatnot and then told me to leave it on and let the battery charge up fully. then the battery light turned off. so i thought it was fine...

this morning my car started up fine, started driving to work...and the light started flashing again. then i noticed my defroster had little power or heat to it. so i turned it off. a block away from work i was at a light, and my radio started turning on and off by itself (so i turned it off) all my lights dimmed considerabley, my airbag light was flickering as well as my battery light, my windshield wipers didn't want to go, and my speedometer was bouncing up and down...the light turned green and my car felt like it was stuggling. i made it to work tho!

my resources and knowledge are limited. people say it is either my battery or alternator. what do you think? should i just get a new one of each? my battery is at least 4 years old anyway. money is just so tight around the holidays and whatnot...

thanks in advance. any input is appreciated.

Any Local Auto Parts Store Will Check Alternator And/or Battery For Free If The Generater Or Alt Light Stays On Its The Alt If Not It May Be The Battery

Welcome to AF!!

If your battery is 4 years old replace it. If I were you I would change the belt on the engine as it sounds like it may be slipping. That is why the light goes out when you rev the engine. It is possible that the alternator is going bad but you can check it with a volt meter to see what kind of voltage you are getting when it is running. Also check the battery terminals for corrosion and make sure they are tight and that the main grounds are tight. The problems you experienced this morning are all related to low voltage and should go away once you get the other issue fixed.

Ditto on the slipping belt. A bad battery can put such a demand on the alternator that the belt will slip. The faster you go the more it slips which could account for the warning light becoming more frequent and brighter. I would get a new battery then address the problem about the warning light. Most batteries last about 3 1/2 years. I agree with GTP Dad. I can't say much more.