Battery or maybe alternator problem? (1 Viewer)

[nyk438]

My 91' 80 keeps having to be jumped ever so often, more often then it should. Tonight the truck almost didn't start or it had a lot of trouble turning over like it was lacking power from the battery. When I'm driving the battery is charing, the needle is up on the monitor on the dash. And when the car is at idle it'll almost die on me after awhile. I'm guessing the battery isn't holding charge? Or could the alternator be not charing it enough? I thought it was that but then if the alternator wasn't working right or was out the lights would all show up on dheh.as


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[landtank]

I helped another member with voltage issues and it was the battery cables. When he turned on enough stuff everything would shut off for an instant and then be real dim. The ground cable is easily sourced through a local parts store but I would go factory for the positive one. You might start with the local ground cable to see if this helps before ordering the positive as it's costly.

Also, do yopu know how to check an alternator and how old is the battery?

 

[Kalawang]

Check the battery voltage with a multitester without starting the engine. If it is exactly 12 volts, your battery is o.k.. If it is less, as in 11.9 or even less, it's time to change the battery.


Kalawang

 

[brent]

Simple way to check if its your alt. it to start engine and remove pos. wire off battery.......if engine dies then it was running on battery and not alt.

 

[97 FZJ80]

Simple way to check if its your alt. it to start engine and remove pos. wire off battery.......if engine dies then it was running on battery and not alt.

I would not use this method to test the alternator on a modern vehicle with electronic controls. Removing the battery from the circuit can cause voltage spikes that can damage the ECU.

 

[Gold Finger]

Simple way to check if its your alt. it to start engine and remove pos. wire off battery.......if engine dies then it was running on battery and not alt.

Brent I think that may be the way to damage an altenator by disconecting the battery while the engine is running, some manufacturers advise against that.

 

[ranma21]

Or you can drop by Autozone, they can check it for you for free!! Good luck!!

 

[Tools R Us]

A fully charged battery will read 12.4+, a lower reading is undercharged or weak/junk battery. With the motor running the reading should be about 14 volts. The first thing to check is the battery terminal connections.

 

[brent]

97 FZJ80 & Gold Finger
You could very well be right, I have never had a problem doing this on my vehicles, probably have done it 3-4 times, if the ECU/alt. can't handle this though how does it handle a bad battery wire, bad connection, bad ground, etc. etc. I would agree the best way would be to go to Sears/AutoZone what have you and have them check it, esp. when you are looking at a couple hundred if you mess up the darn thing.......

 

[ryanjl]

Chances are, if you've been driving the vehicle for a while like this it's not going to be the alt. Battery juice will only get you so far.

I'd bet either a battery or a connection. AutoZone or someplace similar has my vote to see if it's the battery.

 

[Kalawang]

A fully charged battery will read 12.4+, a lower reading is undercharged or weak/junk battery. With the motor running the reading should be about 14 volts. The first thing to check is the battery terminal connections.

Tools,

Frankly, I've never tested my batteries when they were newly bought and under warranty. I normally begin looking at them more closely about 2 years after. My batteries last about 3 years, and readings have always been 12 and no higher. However, when my batteries fall to 11.9 or 11.8, they have a pretty good record of dying totally within 6 months so I try to put money aside for new batteries during those last months.

I'll try visiting the battery store one of these days to confirm if my advice was mistaken.


Kalawang

 

[nyk438]

Battery is about a year old. I'm going to pick up some battery cables this week and see if thats the problem.

 

[Arya Ebrahimi]

nyk, take the truck to autozone or whatever and have them test your batt and alt. It's free and will let you rule those out if they come up ok.

Ary

 

[ryanjl]

I've heard of defective batteries going south in less time...

Like Arya said, Auto Zone will check it out for free. You'd be a fool not to go the "free" route first.

 

[sixsracing]

Buy a battery hydrometer, they are about $1.99 at any automotive parts store. It works just like an anti-freeze hydrometer and has balls that float and give you a reading depending on how many are floating. If one or two cells are significantly lower than the others then the battery is junk.

If you have a multimeter with the vehicle off, check voltage at the back of the alternator (large positive post) to the battery ground post. Then check for voltage between the battery posts. There should be no difference to a slight (no more than .5 volt) difference. If there is more then either you have a ground issue or a cable issue. Ground the case of the alternator to the ground terminal of the battery with some jumper cables, if this diminishes the difference then you have a ground issue. Positive cable can be tested by measuring resistance in ohms, remove the connection at the alternator and at the battery (if you don't you could fry your multimeter) and test for resistance, you should get a .1 reading, if not, replace cable. Same test for ground cable, remove each end etc. Charging system test is to start vehicle and bring to operating temperature, check for voltage at battery with no accessories on, should be 13.5 to 14.5 (give or take) if this isn't the case test voltage at alternator and see if it's different, if it is then you have a cable/ground problem-see above. Test for voltage with vehicle running and all accessories on, voltage can drop to 12.4 to 14.5, if less then check for voltage at alt. All these tests are free and will positively diagnose the problem without replacing good parts.

Removing the positive cable from the battery while the vehicle is running is in no way recommended.

Load tests on batteries that are not properly charged will always result in battery testing bad. So if you go to Auto Zone and your charging system is weak, your going to buy a battery, regardless.

Do not jump your vehicles with late model GM's, some GM's charge at 18 volts on start up, ir your vehicle is connected by jumper cables and you turn the key then severe electrical damage will result. ($3,500.00 damage to an 87 Porsche 928 to be exact)

Hope this helps!

 

[sixsracing]

Beleive it or not, I forgot something. Draw.

To test for draw, remove negative terminal of battery, place test light between cable end and negative post of battery. You should have a very faint glow. If you have a light you can read by then you have a voltage draw. With the tester still connected, have somebody pull each fuse individually until the light goes out. Something on the circuit that fuse protects is drawing power when it shouldn't be.

This will give you the symptoms you are experiencing also.

 

[Tools R Us]

Tools,
Frankly, I've never tested my batteries when they were newly bought and under warranty. I normally begin looking at them more closely about 2 years after. My batteries last about 3 years, and readings have always been 12 and no higher. However, when my batteries fall to 11.9 or 11.8, they have a pretty good record of dying totally within 6 months so I try to put money aside for new batteries during those last months.

Kalawang

Lead acid battery technology maybe different where you are, but US spec batteries are considered full capacity charged at 12.7 V and discharged, having no usable capacity at about 11.7 V. The voltage test is only an indicator of charge and bad cells, should be used with load and hydrometer test results to determine battery condition. Car batterys have six 2.1V cells, so if one is bad the reading will be about 10.5 with a full charge.

A battery with a 12 V reading has about 25% of full charge capacity, if it wont recover to over 12.4 V after charging I would replace it for reliable operation.

 

[nyk438]

I'm going to drop by autozone and get them to check the battery and alt. This might be a stupid quesiton but can they check the alternator while it's in the car or would I have to remove it?

Thanks for all the advice.

-Nick

 

[Tools R Us]

Most use testers from Bear or Midtronics, both are capable of testing the battery, charging and starting systems in the truck.

 

[nyk438]

Most use testers from Bear or Midtronics, both are capable of testing the battery, charging and starting systems in the truck.

Can they test the alternator and does the alt need to be out of the truck?