1990 chrysler 5th avenue, wire leading from alternator to battery burned, voltage very high and kills battery. What's wrong????

Have you put a meter on the back of the alternator to see if it is putting out voltage but not making it to the battery ?

no it would be the internal regulater is bad ,replace it as/ap ,but just to be sure remove it and most parts stores will test it for free.

Regulator failure, the regulator keeps the voltage between a set of given limits when engine revs change turning the over voltage into heat, and is usually integrated with alternator and rectifier, it can on some models be removed from the back of the alternator or you can try an after market unit, and wire it in line from the alternator wire to the battery, mounting the heat sink on the chassis, otherwise your up for a new alternator.

The firewall is where it should be.

Could be a bad battery or a bad alternator, or both.

A bad battery can hinder the performance of an alternator and a faulty alternator can slowly kill a battery.

Check your battery fluid levels and acidity concentration. Do not replenish fluid level with plain tap water as it will finally spell doom on the battery.

If you can still drive the car, take it to your nearest auto parts dealer. They usually have basic maintenance checkups for free. One of them is testing the charging system and they will tell you right up if the problem lies in the battery or the charging system.

A bad battery is a blind alley. If it's bad then replace it.

If you still want to hack at it at home, and all is OK with the battery, there is an old way of telling whether the alternator is working properly. But it's kind of dangerous if you do it wrong.

With the engine running, place the flat part of a flat head screwdriver on the side of the alternator, opposite to the v-belt or serpentine pulley. I'm talking about the center of the back cover of the alternator. Make sure you do not touch any electrical connections with the screwdriver as you may cause a short-circuit and experience fireworks. The tip of the screwdriver should be safely away from any spinning pulleys and belts.

If you feel a magnetic 'pull' on the screwdriver from the alternator body at the center of the back cover, it is a good sign that it is actually doing its job, charging that is. But only that.

An alternator "alternates" between powering all things electrical in your car and charging the battery. There is a small, replaceable thing called a "voltage regulator" that when it goes bad, it kinda gives you battery problems. You can buy one and replace it yourself or you can have someone do the dirty stuff.

In any case, a good, professional, clean, and thorough checkup is always the best option.

Hope it helps.

Bad voltage regulator. Usually built-into alternator.
Start car and unplug battery, if it dies your alternator is dead. Get new alternator. If car keeps running, get a voltmeter and check voltage coming through - should be higher than 12v but less than 18v. Any other number means your voltage regulator is dead, cheaper to get a new alternator.

Well, the Chrysler Fifth Ave. cars from the mid 1980s were known for having alternators and particularly voltage regulators that don't work as well as newer cars. Had a similar charging system to the Mercury Grand Marquis. If you would run it with the lights on for any length of time, the battery will discharge and one may not be able to start the car again. If the high lights are used, it will discharge even faster. I had a rebuilt alternator put on my car but it didn't help matters. I think it is a matter of underpowering at the engineering level, and nobody has to date come up with a solution to make it charge as well as a more modern vehicle's charging system.

Sounds like the battery has lost charge. Charge it overnight at 2-4 amp rate. If it now starts ok, measure the battery voltage with the engine idling--it should read 13.5 to 14.5 volts. If it reads less than 12.6 volts, the alternator is not charging the battery. Take the car to an auto parts store and have them test the battery, alternator, and voltage regulator (usually for free). They will be happy to sell you any needed parts. Hope this helps!

if you have a multi meter,
check voltage at battery with car running,should be at least 13-14 volts,
now turn on fan motor to high,flashers on,radio on, and check voltage at battery,regulator should have adjusted voltage to handle the load,should still be 13-14 volts,
now turn all that stuff off,and turn on headlights and recheck battery voltage,if below 13-14 volts replace regulator,if voltage is spiking higher than 14volts replace regulator.you do not need other belts.

Alternator may have an internal short...remove it and have it tested. Also make sure to check the wire that smoked and any other fusible links to make sure they have not burned through and are no longer carrying voltage. Pay attention to wiring when putting it back together...any big sparks etc when re-attaching battery lead indicates you still have a short somewhere.