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Alternator question.

centermass556centermass556 Posts: 3,618 Senior Member
in Clubhouse #1
So the explore died today. The battery is not charging. To determine whether it's the battery or the alternator, I should be able to jump up the explorer and then remove the battery cable. If the explorer remains running that it is the battery, If the explorer quits running it is the alternator. Is this a correct assessment?
"To have really lived, you must have almost died. To those who have fought for it, freedom has a flavor the protected will never know."
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Replies

  • BufordBuford Posts: 6,724 Senior Member
    #2
    That's dangerous territory doing that. Can you borrow a volt meter?
    Just look at the flowers Lizzie, just look at the flowers.
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  • VarmintmistVarmintmist Posts: 8,305 Senior Member
    #3
    If you charge the batt and it keeps running and starting but and isnt charging it is the alternator. If the battery will not charge it is the battery.

    Yes if you pull the positive the car should keep running. Not unsafe at all as long as you use a little common sense.

    edit, might want to have a non shade tree mechanic that has worked on cars with computers chime in though, it used to work
    It's boring, and your lack of creativity knows no bounds.
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  • BufordBuford Posts: 6,724 Senior Member
    #4
    Electronics aren't forgiving and expensive.
    Just look at the flowers Lizzie, just look at the flowers.
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  • wddodgewddodge Posts: 1,150 Senior Member
    #5
    centermass556 wrote: »
    So the explore died today. The battery is not charging. To determine whether it's the battery or the alternator, I should be able to jump up the explorer and then remove the battery cable. If the explorer remains running that it is the battery, If the explorer quits running it is the alternator. Is this a correct assessment?

    This worked on pre-electronic controlled vehicles but not anymore. Unhooking the battery while running could cost you $$$$$ in failed electronic control modules.

    You really need a scanner or at least a voltmeter to check the alternator output to see if its the alternator, the powertrain control module that controls the voltage output of the alternator or the battery. It's by far easier to have the local parts store to put a load test on the battery to check it than to get into the charging controls.

    Denny
    Participating in a gun buy back program because you think that criminals have too many guns is like having yourself castrated because you think your neighbors have too many kids.... Clint Eastwood
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  • jbp-ohiojbp-ohio Posts: 10,943 Senior Member
    #6
    Go to Advance Auto, Autozone, O'Reillys, etc..... They will test it for free
    "The democracy will cease to exist when you take away from those who are willing to work and give to those who would not." Thomas Jefferson
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  • centermass556centermass556 Posts: 3,618 Senior Member
    #7
    Yeah I know I can get it tested. But the thing is sitting in Lowe's parking lot on Muldoon. I was hoping I could just take a best guess pull the alternator or the battery come back replace it and drive home
    "To have really lived, you must have almost died. To those who have fought for it, freedom has a flavor the protected will never know."
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  • Fat BillyFat Billy Posts: 1,813 Senior Member
    #8
    Get it started and if the battery is charging at 14.2 volts the alternator is good. This will require a volt meter to check. The alternator needs electricity to make electricity. If you jump it off and it's dies when the cables are disconnected but it makes voltage when they are connected the battery is kaput. Old red neck trick is to open the battery caps and put 1/2 an aspirin in each cell and revive a bad battery. The aspirin helps remove the oxide off the plates. If cells are dry fill them before the aspirin. Get it running and go to a parts store, most will check it for free. :up: Later,
    Fat Billy

    Recoil is how you know primer ignition is complete.
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  • BufordBuford Posts: 6,724 Senior Member
    #9
    centermass556 wrote: »
    Yeah I know I can get it tested. But the thing is sitting in Lowe's parking lot on Muldoon. I was hoping I could just take a best guess pull the alternator or the battery come back replace it and drive home

    How old is the battery? If it's over 5 years old just buy a new one install it and it will get you to where you need to go.
    Just look at the flowers Lizzie, just look at the flowers.
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  • TeachTeach Posts: 18,428 Senior Member
    #10
    I've seen voltage spike to over 100 VDC on an oscilloscope when a battery cable is removed. The battery is the "shock absorber" in the electrical system, and when it's not there even for an instant, things go crazy. If you insist on the shade tree check, a $75.00 alternator swap could turn into hundreds of dollars' worth of expensive fried electronics. Computers don't like voltage spikes! Get a $5.00 digital voltmeter at Radio Shack or Auto Zone and check the battery terminal voltage with the engine running. It should be 13 volts or more from a good alternator.
    Jerry
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  • Big ChiefBig Chief Posts: 32,995 Senior Member
    #11
    centermass556 wrote: »
    Yeah I know I can get it tested. But the thing is sitting in Lowe's parking lot on Muldoon. I was hoping I could just take a best guess pull the alternator or the battery come back replace it and drive home

    Get it started/towed and get them both tested. Your car Ins or cell phone/credit card probably has a towing service connected with it.

    You may only need one or maybe both depending on your battery. I got stranded in my old 2000 Saturn southwest of Atlanta just as I got off I-75 because of of an accident. I was in a small town and the battery light came on then it shook and died and I was also in a Lowes parking lot!

    Turned out the battery was going (4+ years old) and the alternator was bad. So I had them both replaced. Cost me out the butt, but I was on my way to Huntsville in a few hours. Some kinda USA Battery Shop did it for me, but considering hotel/cats in pet taxis in the car/guns in truck....it was a all things considered bargain for me to be on my merry way. They stayed open late to get me going that night too. :up::up:

    The Redstone Auto Craft Shop would go anywhere no matter how far to pick up a vehicle for soldiers/retirees for a small fee. Maybe your post will do the same and will help you????
    It's only true if it's on this forum where opinions are facts and facts are opinions
    Words of wisdom from Big Chief: Flush twice, it's a long way to the Mess Hall
    I'd rather have my sister work in a whorehouse than own another Taurus!
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  • centermass556centermass556 Posts: 3,618 Senior Member
    #12
    So, yup the Explorer died on the way to meet the wife for lunch. A kind lady towed me with her truck out of the road and into the Lowes Parking Lot. I could've had it towed, or even called someone at the office to come with their truck to come tow me to the Hobby Shop. But, I was pretty sure I could identify the issue with some shade tree troubleshooting (thanks for that tip Teach, I never knew that much voltage was generated). So, I took the best guess off of what I saw from the Explorer and pulled the alternator (I love older trucks! very easy to do with some tools). I had my wife drive me and the alternator up to Autozone. They tested it. Failed all three categories on the tester. Came back, installed it, jumped the truck, and boom it started right up. I let It run for about 30 minutes with a good amount of RPMs. Nothing, nada, nil on the battery. Wouldn't take a change at all. But, the truck would run. SO, looks like I need to go get a new battery also. It wouldn't hurt to also get a new belt. I noticed the belt was starting to split when I put the new alternator in.

    Sometimes it sucks when you guys are right...:cone head: Bu, I do thank y'all for the quick responses...
    "To have really lived, you must have almost died. To those who have fought for it, freedom has a flavor the protected will never know."
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  • bisleybisley Posts: 10,815 Senior Member
    #13
    Buford wrote: »
    How old is the battery? If it's over 5 years old just buy a new one install it and it will get you to where you need to go.

    That's my reasoning, as well. It's an easy fix if it works, and if it doesn't, you would be buying a new battery soon, anyway. Changing the alternator is not a big deal, but if you live in Alaska, it probably sucks enough that I wouldn't want to do it in Lowe's parking lot on Halloween night.
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  • CHIRO1989CHIRO1989 Posts: 14,857 Senior Member
    #14
    centermass556 wrote: »
    So, yup the Explorer died on the way to meet the wife for lunch. A kind lady towed me with her truck out of the road and into the Lowes Parking Lot. I could've had it towed, or even called someone at the office to come with their truck to come tow me to the Hobby Shop. But, I was pretty sure I could identify the issue with some shade tree troubleshooting (thanks for that tip Teach, I never knew that much voltage was generated). So, I took the best guess off of what I saw from the Explorer and pulled the alternator (I love older trucks! very easy to do with some tools). I had my wife drive me and the alternator up to Autozone. They tested it. Failed all three categories on the tester. Came back, installed it, jumped the truck, and boom it started right up. I let It run for about 30 minutes with a good amount of RPMs. Nothing, nada, nil on the battery. Wouldn't take a change at all. But, the truck would run. SO, looks like I need to go get a new battery also. It wouldn't hurt to also get a new belt. I noticed the belt was starting to split when I put the new alternator in.

    Sometimes it sucks when you guys are right...:cone head: Bu, I do thank y'all for the quick responses...

    No rule that says two things can't be going wrong at the same time, easy fix it sounds like though:up:
    I take no pleasure in the death of the wicked, but rather that they turn away from their ways and live. Eze 33:11
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  • TeachTeach Posts: 18,428 Senior Member
    #15
    A failing alternator will put extra strain on a battery, which can cause it to fail prematurely. Starting batteries are designed to cycle in the upper 25% of their capacity, while a "deep cycle" battery such as one for a trolling motor, power wheelchair, etc. can be discharged/recharged to 75% of its capacity without damage. Deep cycle batteries don't have the heavy current capability to run high-load devices like starters, however.
    Jerry
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