electrical/ignition problem

[Necroblade78]

Hello all. Sadly, my first topic post on here is going to be geared toward finding a solution to my car's problem.
I purchased this 2003 Focus (2.0 SPI) used this past spring and it had 73k miles on it. It now has almost 90k. About a month or so after I purchased it, I started noticing that the gauges (all 3; speedo, fuel and temp) would peg back and forth and after a few mins they would settle down and function properly. I also would notice that the battery light would come on intermittently and headlights have been dimmer than normal but would brighten up periodically while driving..especially when accelerating. This has been an ongoing issue up until today. I was on the highway doing 70mph and the gauges suddenly dropped and was a good 5 mins before they sprang back to life. About 10 mins later, the car seemed felt like it had abrubtly downshifted to a lower gear and the gauges again dropped dead and came back on several minutes after. The rest of the trip (6 more miles) was fine. After spending an hour or so at the mall I started to return home. I made it a good 20 miles with no issues until disaster struck. I pulled up behind a line of cars at a red light and after sitting idle for several seconds, my car sputtered and died...it has not started since. When I tired to start it, the starter would make a repeated clicking noise and all the inidicator lights on flash rapidly. Someone was nice enough to stop and offer me a jump...but this was a no go. After waiting about 30 mins with the jumper cables on and the other vehicle revving to try to juice up my battery, it still did the same thing. We even tried removing both leads from the posts and I scraped the outer edges of the battery posts as well as the insides of the terminals to help make a clean connection. This did not help either.
Now, before I spend a huge amount of money on needless repairs and possibly a garage visit. is there anyone out there that can possibly pinpoint what is wrong here? I have pretty much boiled it down to a battery that will no longer hold a charge, possibly a dead alternator and possibly bad/corroded battery cables. I know i can afford to replace all of those items but is there anything else I should check? Thanks in advance!

*edit* forgot to mention, the battery, cables and alternator are all original parts.

[locdowg7]

Do you have a voltage meter? If you do check the running voltage should be high 13 to mid 14s on DC voltage. Also check AC voltage should be real low less then a half of a volt. If AC is to high or DC is not in spec then you need a new alternator. It sounds to me like your ac voltage is way to high playing havoc on the rest of you car.

[Necroblade78]

That's just it...I can't get it started now. Tried jumping it and the relays still just click.

[locdowg7]

Without a volt meter its all just speculation. Theres all sorts of things that coulda happened. Lets start with battery voltage with ignition on and when your trying to crank.

[Necroblade78]

Ok, thanks for the replies. I put a brand new battery in the car and it started up stronger than it ever has since I bought it. I took it to autozone and they hooked up an alternator tester. After starting it was at 12v and after 10-20 secs it went to 14v then the tester showed 30a. The employee stated that the amperage should be around 85a. Is he correct?

[locdowg7]

Yes it should be at 85a if there is a full load on the system but I doubt he put a full load on it. Do yourself a favor and go buy a digital volt meter and LMK what those 2 volt readings are.

[Zoomer69]

The symptoms you described are precisely what happens when the car doesn't have a sufficiently charged battery. If the old battery was original, it was due for a replacement anyway.

It wouldn't hurt to have it checked at another place to confirm the alternator is also faulty. The alternator is old enough that it's likely due for a replacement too.