My vette wouldnt start the other day since there was no battery power at all. I had to use the jump n carry to get her running. At that point when she was running I noticed the alternator was hot and the voltage was reading 13.2- 13.6 which is low to me. This is the third time I had to replace my alternator as well as the battery. What gives ? I got both new and installed and the alternator is still hot and the voltage now reads 13.8 - 13.9. It normally reads 14 - 14.1. Do I have another problem I should be aware of ?

 

I can give you my opinion of your problem. You either have a bad battery or you have an electrical short that is draining your battery. The newer cars were not designed for the alternator to recharge the battery from a point of being dead. Instead the alternator is used to replenish the charge due to starting and running the operating electrical system. You will continue to burn altenators until you fix the "real" problem of battery drain/bad battery. My $.02 for what its worth. Hope this is helpful.

 

Dead batteries draw a lot of current at the beginning of recharging. Your alternator has slightly low output voltage and is hot because it is delivering all the current the voltage regulator will allow. Normally the voltage regulator attempts to maintain 14.7 volts out, but if the current drawn is at the maximum rating, the voltage regulator limits the current output by reducing the output voltage. This is what is happening to your alternator. NEVER use your alternator to charge up a dead battery!!! it will shorten the life of your alternator. Charge up your battery for at least 24 hours with a battery charger, it is easier on both your battery and your alternator. After charging up your battery you should see the normal 14+ volts across the battery with the engine running.

 

Try to charge the battery on a battery charger and not by using the alternator. This will wear out an alternator quick.

 

So are you saying that it is normal for the alternator to be hot ? even if both battery and alternator is new ?

 

I tried charging my battery but it wouldnt do so I brought both the alternator and battery in to the store for an exchange with warranty.

 

Where can I find this electrical short ?

 

You had a discharged battery and if you understood my first reply, you would know that your alternator is supplying high current to charge up a discharged battery. The current is at the rating of the alternator and this makes the alternator run hot and this is normal. DO NOT USE YOUR ALTERNATOR TO CHARGE UP A DEAD BATTERY!!!!!!!!!!!!!!!!!
Hot alternators don't last very long. Charge your dead battery back up with a battery charger that plugs into a wall outlet and requires 24 hours to do so.
If you do not drive your car often, you will continue to replace batteries and alternators because car batteries self discharge 1% each day even disconnected. When lead acid batteries discharge, lead sulphate collects on the plates and lead sulphate is a good insulator. A sulphated battery is a door stop and will not draw current from a battery charger. Buy an interval timer (turns your lights on when you aren't home) and have it charge your battery each day for its minimum interval (usually 15 mins). This will keep your battery charged and you will experience normal battery life. Each time you totally discharge your battery and charge it back up, you reduce its amp hour capacity, so keeping it charged is a much better way to treat your battery!!!!

 

Well like I said before I have a new battery in the car with a new alternator right now that I picked up last night. The alternator is hot with a brand new battery in it. Why would it be hot with a new battery is my question. Thanks for the responses.

 

Due to the age of your car I would check alternator output at the alternator compared to what it's showing at the battery. There shouldn't be much difference, if there is you have a voltage drop situation due to old wiring or cables. Check critical grounds. Also is your belt good, not glazed, etc.? Is your tensioner in good shape? A belt can slip slightly without your knowing it when it's under load. This will heat up the pulley, the shaft and eventually overheat the bearings in the alternator causing premature failure. Heat is an alternator's worst enemy. They do run pretty hot these days but don't need to run any hotter!

 

You have a new battery that is discharged! You can tell the state of charge of any car battery by measuring the battery terminal voltage with no load on the battery and the engine off. 12.0 volts and below, discharged. 12.9 volts and above, fully charged. 12.5 volts would be at 50% of its amphour capacity.

 

The vette is a bitch that likes to be driven...

If you let her sit for too long, too often... she dries up because she's always drawing a little current.

The C4's need to be run often to have a reliable battery/alternator because the design is to replace startup power loss and minimal constant drain (some fellas run 140 amp units for example because of other mods).

My daily driver doesn't have the problem because the battery doesn't drain too low to put an unreasonable load through the system (to recharge the draining battery).

I say take her for a ride more often and you'll have fewer problems. Electrically that is, bearings and brakes are another story though...

my2cw

 

The alternator always runs hot. The question is how hot is bad? If the hot engine is idling the air being discharged by the alt fan is hot. Check out a few friends cars and compair this "hot". A bad alternator will sometimes discharge air that is blistering hot! It feels like you can light a match with the heat.

I'd suggest that you look at the volt gauge and use this an idicator of proper operation. Also check and clean the cable ends and the cable condition. If the cable has any signs of corrosion near the ends, replace it.
-JRC-

 

Well I checked my voltage as I was driving to work and now the battery voltage reads 13.5. But when stopping at a light it drops all the way down to 12 sometimes. I do know one of the terminals has some corrosion on the end cable that hooks to the " + " and the outter rubber is stripped in some ways. I did shop around at some auto parts store to find a replacement cable but they had none that looked like mine did. Where can I find the proper cable? and how much should I expect to pay ? Thanks.

 

You might want to check all cable connections including the engine grounding strap.

 

CHeck with your local NAPA store. My buddy just ordered a set made by Belkin for the Corvette. They had to order 'em. Can't say for how much..... -JRC-

 

make sure your interior lights go off after a bit when the vehicle is parked. If you manually turn them on, they will stay on until the battery is drained. Check for any other sticky switches , brake light, anything that will draw amps when parked. I had a electric antenna that would not stop turning once... As for the heat of the alternator, I have a lifetime alternator. If it goes out, i just trade it in. These alternators are 100 plus amp outputs.

 

"I do know one of the terminals has some corrosion on the end cable that hooks to the " + " and the outter rubber is stripped in some ways. "

If there is "some corrosion" that you can see, the inside of the connector is probably gone. I would replace both positive and negative cables.

 

Thanks.. I will check out the NAPA store int he area. I hope this cures the problem somewhat.

 

87vette, I don't want this to sound like a flame, but have you read any of the posts about engine compartment fires? The problems your having can be real fire starters if your not careful. You really need to invest some time and go through the engine compartment with a fine tooth comb. Replace ALL the cables that look even suspicous. Inspect ALL the relays and the attaching connectors for bare wires. A common connector that "usually" is found with bare wires is between the wiper motor and LH valve cover, on the firewall. Its a real bugger to get to yet will fry an engine compartment if the wires touch. Your going to be in there yankin and tuggin on cables that could very well cause for other problems to surface such as this. Do a SEARCH for "bare wires" and you'll find a lot of information.

I now carry a fire extinguisher, battery cable wrench and a cable cutter as a backup for electrical fires. Paranoid? Nope! Just don't wanna see all my hard work go up in flames as some other CF'ers have posted in the past.

Gonna be gone this weekend, IM or email me and I'll be glad to help as best I can. Steve -JRC-