Alternator issues?

[OOge]

A week ago, my '00 venture wouldn't start. I just drove to the store (1mile) and the car was dead when I tried to start it. Boosted the battery, drove home, tried to start and dead again. So replaced my battery. Today same thing. Drove a mile, came home and dead again. No power, no lights. After a while I'll get a bit of power back but not enough to start.

I have noticed that sometimes the control center light turns very bright. It only happens for a second. Headlights also dim a bit, running idle or when opening the windows.

Could it be an alternator issue.

[LMP]

Obviously, the battery is taking all the load.
Yes...alternator is first suspect...connect a voltmeter to the alternator (heavy gauge wire at the back) , run the engine...should read around 14.5 volt.....then test at battery (engine still running) ...should read the same. (or the other way around) . THere is a fusible link between the alternator and battery. Failure of this link will not charge the battery even if the alternator tries.
IF the battery stays at 12V (engine still running and alternator showing 14.5 v) , the fusible link between alternator and battery link is shot.

OF course, if the running alternator stays at 12V (which is battery voltage carried to the alternator) , the alternator is shot....in most cases, the built in voltage regulator ($20-$30) is the culprit and it can be replaced if you or a friend can use a soldering gun. I did it twice...( .I also changed the built in diode bridge once: one failed diode (one of six) reduces charging power...but not entirely).


Testing for the fusible link can be done like this also: Test the heavy gauge wire at the back of the alternator with engine not running and everything off. A voltage test is a first step...as reading zero at the alternator would indicate link failure, period.......but even if it shows the 12V battery voltage....it can be misleading as a failed fusible could carry enough of that tiny current (from the battery) that is sufficient for the voltmeter to show a voltage....so use something like connecting a headlight bulb to this wire on one side, and ground on the other ...if the light stays dead, the link is shot.

Sorry you change the battery..unless it was already 5-6 year old (normal lifespan) which would then be considered "preventive maintenance".. Batteries are often the victim, not the cause, of other failures...

...reading back your post, it seems however that some charging occurs when engine runs at higher speed...as you say "lights dim when engine idles"..... are you sure nothing is draining the battery while car is stopped ?

[OOge]

Originally Posted by LMP

Obviously, the battery is taking all the load.
Yes...alternator is first suspect...connect a voltmeter to the alternator (heavy gauge wire at the back) , run the engine...should read around 14.5 volt.....then test at battery (engine still running) ...should read the same. (or the other way around) . THere is a fusible link between the alternator and battery. Failure of this link will not charge the battery even if the alternator tries.
IF the battery stays at 12V (engine still running and alternator showing 14.5 v) , the fusible link between alternator and battery link is shot.

OF course, if the running alternator stays at 12V (which is battery voltage carried to the alternator) , the alternator is shot....in most cases, the built in voltage regulator ($20-$30) is the culprit and it can be replaced if you or a friend can use a soldering gun. I did it twice...( .I also changed the built in diode bridge once: one failed diode (one of six) reduces charging power...but not entirely).


Testing for the fusible link can be done like this also: Test the heavy gauge wire at the back of the alternator with engine not running and everything off. A voltage test is a first step...as reading zero at the alternator would indicate link failure, period.......but even if it shows the 12V battery voltage....it can be misleading as a failed fusible could carry enough of that tiny current (from the battery) that is sufficient for the voltmeter to show a voltage....so use something like connecting a headlight bulb to this wire on one side, and ground on the other ...if the light stays dead, the link is shot.

Sorry you change the battery..unless it was already 5-6 year old (normal lifespan) which would then be considered "preventive maintenance".. Batteries are often the victim, not the cause, of other failures...

...reading back your post, it seems however that some charging occurs when engine runs at higher speed...as you say "lights dim when engine idles"..... are you sure nothing is draining the battery while car is stopped ?

I'm positive nothing is draining the battery. The delco battery I had was 3 years old. So I replaced the battery with a new one last week. After driving for a week, same thing. no power. Just like the other battery. So either the car can drive a week on one battery charge, or it charges just a bit, but not enough for small distances. It drove my kids to school this morning, about a mile...no problems at all. But when I wanted to pick them up, nothing.

[OOge]

BTW, where is the fusible link located...

[LMP]

It is part of a wire going from the alternator to a binding post ....probably the starter (that is the case with my '93, probably same sith yours) . Here is how it shows on mine as Fusible Link H
www.avigex.ca/xport/fusiblelinkh.jpg
www.avigex.ca/xport/chargingstarting.jpg

It is known as Fusible link A on later models...but still connected in same way...the wire is heavy gauge AWG10 red or rust
www.avigex.ca/xport/starting19958.pdf

Several with link prolem have routed a new #10 wire from alternator direct to battery post without bothering with existing wire/fusible

[OOge]

I will check the link also. Still think it is a strange thing that it works for a week with a new battery. Maybe it doesn't charge enough on a smaller trip like a mile. And charges enough on a 20mile trip. Can't believe it is the battery, as it is just a week old. Of course you never know, but chances are low.
If the fusible link is bad, it wouldn't charge at all I guess.

[LMP]

Do not loose time and money with the battery..it is not the culprit. YOu cannot guess out what it is just by trial and errorL : you have to use a voltmeter (multimeters arre available at less than 20$) and, first of all, verify voltage at battery with engine running. YOu should measure near to 14.5 volts (meaning link is OK) ...then , always with engine running, run heater blower, rear defroster...battery voltage might lower a bit but come back near 14 volts if engine is run at higher speed. If you have voltage with no load, and voltage lowers significantly with added load, then the alternator does not deliver enough current to supply loads and charge battery at same time.

[OOge]

When I put my multimeter on the battery I see (when engine idle) that is goes from 14.3-14.55 (when tunring everything on it went up to 14.95 and went back down). Is it normal that the voltage swings a lot. It is not steady at 14.55.
When I test another car it is steady at 14.75

[rkvons]

You could try starting your vehicle and then, while it is running, disconnect the battery and see if it stays running. Also, while battery is disconnected and engine is running, measure the voltage at the battery terminals. Then put a load on the battery terminals and see if it can handle it. Like a headlight.

[LMP]

Originally Posted by OOge

...Is it normal that the voltage swings a lot....

Somewhat unexpected....but these voltages prove the alternator is charging. About disconnecting the battery while running....although I did this at times, mmm..ancient times.... I would not risk the alternator developping a voltage spike when battery load is removed as this has been seen to fry the computer or other electronic items. Yes, can be done, but at a risk.

...I've had problems with corrosion developping on battery connectors/cables, even at the starter tie point (and reported by others on this forum) ..I would not miss the opportunity to ensure they are all totally free of oxydation...freak voltage variations can be linked to such cause as well as the problems you describe. Simple facts like this must be checked out at least.....

[Tech II]

I agree, don't disconnect/reconnect a battery while car is running, due to spikes.....

Check voltage when the alternator is hot.....load the the system...turn on lights, wipers, blower on high, and rear defogger....voltage will probably drop to 12 volts, but if you rev engine to 1500 rpms, voltage should increase to at least 13.0 volts......if ok, then I would be looking for a draw....I assume the cables were clean and free of corrosion when you replaced battery?

One more thing...you check/test an alternator with a fully charged battery, not one that is low on charge....alternators are not made to charge low batteries(that's why you get those stickers on new alternators).....alternators are just there to recharge the voltage lost from cranking the vehicle, and then they basically run the electrical in the car when it's running.....when it doesn't do this, then it runs on the battery and discharges it....

[aleekat]

Originally Posted by Tech II

I agree, don't disconnect/reconnect a battery while car is running, due to spike..

Ah, the days of generators.

[j cAT]

Originally Posted by aleekat

Ah, the days of generators.

the reason is because the voltage surges will damage the electrical system /computer.

In the pre 1975 era you had not much anything close to a computer.

the more expensive today a vehicle is with more electronic controls on just about every thing this could cause a huge amount to repair.

[j cAT]

Originally Posted by OOge

When I put my multimeter on the battery I see (when engine idle) that is goes from 14.3-14.55 (when tunring everything on it went up to 14.95 and went back down). Is it normal that the voltage swings a lot. It is not steady at 14.55.
When I test another car it is steady at 14.75

with the engine at normal operating temp [running for about a half hour], the voltage at the battery teminals engine idling should be 13.75-14.25volts . the alternator should be quite warm . with the cold engine you would get the 14.75 volts.

what can be going on is the alternator has a bad diode that drains the battery on engine shut down. make sure those cables cpnnectors to the new battery are cleaned.

the new battery should be load tested after you charge it with a battery charger to determine if you got a new defective battery.

the store you purchased the battery will have this tester which will suck about 500amps out of it with a scale to determine its health.