Electrical question....HELP
Thread Starter
Pro
Joined: Mar 2000
Posts: 675
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From: San Jose CA
Electrical question....HELP
My alternator evidently went dead, and for the last couple of weeks, my Sears DIEHARD finally died HARD!:cry
I replaced the alternator and the battery won't hold a charge, so I have to get that replaced.
My question is...if the car is started and running (with the new alternator), and I put a current clamp on the +battery, and I turn on the lights. The ammeter shoots up to about 13 amps, OK,...but then if I leave the lights on, the current slowly decreases and keeps decreasing, I turned it off before it got to far down.
My main question is, shouldn't the alternator be able to support the entire car's power requirements? The battery will be changed at lunchtime today, and I will see if I have the same problem. But any ideas as to the alternator current decreasing? :confused: :confused:
[Modified by Laserjohn, 8:09 AM 3/18/2004]
I replaced the alternator and the battery won't hold a charge, so I have to get that replaced.
My question is...if the car is started and running (with the new alternator), and I put a current clamp on the +battery, and I turn on the lights. The ammeter shoots up to about 13 amps, OK,...but then if I leave the lights on, the current slowly decreases and keeps decreasing, I turned it off before it got to far down.
My main question is, shouldn't the alternator be able to support the entire car's power requirements? The battery will be changed at lunchtime today, and I will see if I have the same problem. But any ideas as to the alternator current decreasing? :confused: :confused:
[Modified by Laserjohn, 8:09 AM 3/18/2004]
Racer
Joined: Jan 2004
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From: 20,000 leagues under the sea
Re: Electrical question....HELP (Laserjohn)
First, I am no expert but I think this is correct. The ammeter is showing the direction of current flow, not battery voltage. When you turn on the headlights etc. the draw on the battery increases, which means the output must increase (thats the 13 amp increase), at a higher rate than the draw. As the battery regains its capacity the ammeter will show a gradually decrease in current flow, back to near normal reading. :cheers:
Thread Starter
Pro
Joined: Mar 2000
Posts: 675
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From: San Jose CA
Re: Electrical question....HELP (68raggtop)
As the battery regains its capacity the ammeter will show a gradually decrease in current flow, back to near normal reading. :cheers:
Melting Slicks
Joined: Oct 2002
Posts: 2,865
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From: I may be getting old but I refuse to grow up
Re: Electrical question....HELP (BigBadOrange)
Get the alternator checked. Sometimes putting a new alternator on a dying or dead battery will fry it.
Steve :steering:
[Modified by stpman, 12:20 PM 3/18/2004]
Le Mans Master
Joined: Oct 2002
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From: Las Vegas - Just stop perpetuating myths please.
Re: Electrical question....HELP (Laserjohn)
My alternator evidently went dead, and for the last couple of weeks, my Sears DIEHARD finally died HARD!:cry
I replaced the alternator and the battery won't hold a charge, so I have to get that replaced.
My question is...if the car is started and running (with the new alternator), and I put a current clamp on the +battery, and I turn on the lights. The ammeter shoots up to about 13 amps, OK,...but then if I leave the lights on, the current slowly decreases and keeps decreasing, I turned it off before it got to far down.
My main question is, shouldn't the alternator be able to support the entire car's power requirements? The battery will be changed at lunchtime today, and I will see if I have the same problem. But any ideas as to the alternator current decreasing? :confused: :confused:
[Modified by Laserjohn, 8:09 AM 3/18/2004]
I replaced the alternator and the battery won't hold a charge, so I have to get that replaced.
My question is...if the car is started and running (with the new alternator), and I put a current clamp on the +battery, and I turn on the lights. The ammeter shoots up to about 13 amps, OK,...but then if I leave the lights on, the current slowly decreases and keeps decreasing, I turned it off before it got to far down.
My main question is, shouldn't the alternator be able to support the entire car's power requirements? The battery will be changed at lunchtime today, and I will see if I have the same problem. But any ideas as to the alternator current decreasing? :confused: :confused:
[Modified by Laserjohn, 8:09 AM 3/18/2004]
So I guess what I advise is have them both tested. Use a battery tester (load cell) to test battery and not just a voltmeter. Also a alternator needs to but out over 13.6 volts to charge a lead acid battery and needs to run higher rpm than at idle. What this means is that at idle you are usually measuring just batterry voltage and when you rev it up (over 1,500 rpm) you can measure alternator output. :yesnod:
Good luck :seeya
