Car battery/alternator question

[silverpig]

1991 Ford Tempo
New alternator installed ~3 yrs ago
New battery installed ~1 yr ago

I drove the car this morning and it ran fine. I had to drive it up a small mountain so it was working pretty hard. I parked it and turned it off. No lights were left on. I came back to it a few hours later and it was dead. Nothing electrical would work.

I figured it was just the battery as that's happened before, but nothing was left on so I don't know how exactly it happened. The only thing I can think of is that my radiator fluid was low so perhaps the car kept the fan on trying to cool the engine and that killed it. I'm not sure though.

So I got a friend to bring a portable jump starter over and the car started up fine. I drove it a short distance, filled up the radiator, turned it off, and tried to restart it. Nothing. I used the portable charger again and it started up no problem. I left it to idle for 10 minutes and came back to find it had stopped.

I used the portable starter again and it started up fine, then drove for about 15 minutes before the car died while idling at a light. It now sits at the side of the road somewhere.

Is it just the battery, or is the alternator messed up too? I can buy a new battery and install it tomorrow, but don't want to waste $70 if the alternator is the culprit and will just kill the new battery as well. I also don't want to pay for a tow and service if it is just the battery. I also don't want to buy a new battery if I can just recharge the old one.

What's the smart thing to do here?

 

[Pliablemoose]

AutoZone & have alternator tested...

Buy refurb or have yours rebuilt

 

[MDE]

AutoZone and have them test your battery. If it's not the battery, check the alternator and cables.

 

[Pacfanweb]

Sounds like your battery just took a dump. Get the alternator tested to be sure.

 

[silverpig]

I'll borrow a friends car tomorrow and jump mine. I'll drive it in to my mechanic friend and charge the battery. I won't ask him to test the alternator (unless it's a 10 second test), then go with what I learn. Hopefully it's just the battery.

I'd really like to know why it happened in the first place though.

 

[LTC8K6]

Died at the traffic light after 15 minutes of driving?

Shouldn't have quit if the alternator is working.

Sounds like a bad alternator. Sounds like the battery is getting a little bit of a charge from your jumps, and the charge lasts long enough to keep the ignition system and the computer powered up for a short while on the battery alone.

The fact that it runs for a little while after you charge the battery would indicate to me that the battery is accepting a charge.

If you fully charge the battery, or replace it, you will probably be able to drive quite a ways in the daytime, and you may think the problem is solved, but you've really just been running on the battery alone, and the car will suddenly quit.

 

[cardiac]

Do you have a voltage gauge in the dash or just an idiot light? If it is a gauge, it should show between 13-15 volts if the alternator is working. If it's the light, does the light come on? As LTC8K6 commented, it should run if the alternator is putting out the proper voltage.

Bob

 

[silverpig]

Yeah, that's what I thought. I'm going to try to charge it up as best I can using another car, then drive it into a shop.

Anyone got a ballpark on what an alternator + labour on a 91 tempo would be?

 

[exdeath]

Voltage won't tell you anything about a battery. You need to put a resistive load and check current. It can show 12+ volts just sitting in the car, but fall flat on its face like it's not even there when you load it.

Get the battery fully charged and load tested before spending any money. If the load test passes, then you can start looking at the charging system.

Most likely an internal short in the battery from vibration or factory defect, low fluid, or it's just worn and ready to retire, something like that.

If you need a battery I'd recommend the Optima red top's. They are pricey but will likely be the last battery you ever buy, they are awesome. The oldest one I have has given me 3 years of maintenance free service so far and it still starts up faster than any other battery I've ever had before. It's like you touch the key and fear that your starter is going to explode fast.

 

[Vetterin]

If you just bought your battery last year it should still be under warranty so just take it back and have them give you a new one. FWIW, Tempo's are noted for having their
ECM's go bad from heat soak so don't rule that out.

 

[Killrose]

Make sure they take a good look at your Battery ground and Positive cables too. I had a similar problem with a corroded ground cable which was masked at first by the fact that when you jump start a car you are usually attaching the grnd side to the engine. The frame grounding point happened to be pretty bad and the car would not start on its own even though the battery was perfectly fine.

 

[silverpig]

Well I just managed to get it home. I charged it off of another car for 10 minutes and drove it back here without any lights or the radio on. It died as it was being parallel parked outside my building (lights came on to assist the parking).

I bought a multimeter to test the electrical, but it didn't come with a battery lol.

I'm gonna charge the battery up on a trickle charger, then do some tests on the electrical. I'll also check the alternator belt to see if it's just not turning the alternator properly, then I'll look at getting a new alternator.

 

[boomerang]

In response to your Topic Summary;

POS Car