Bad Alternator?
10-02-2007, 10:26 PM
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Bad Alternator?
So as I was driving home today, my sub was fading in and out. It would kick in every now and then..... I thought it was a connection problem, but there isnt one.
....parked my truck outside, and went to move it about 2 hours later. When i started it, it BARELY started. I drove it for about 5 minutes, and stopped at the gas station. When I got back in to start it up, it acted as if the battery was dead. I got a jump, and then drove it back home..... turned off the truck, and tried starting it again, but it wouldnt turn over. Just "clicked" repeatedly......
Bad alternator? or bad battery?
Ive done a search, couldnt really find much that matched what I am dealing with (With the sub fading in and out)
....parked my truck outside, and went to move it about 2 hours later. When i started it, it BARELY started. I drove it for about 5 minutes, and stopped at the gas station. When I got back in to start it up, it acted as if the battery was dead. I got a jump, and then drove it back home..... turned off the truck, and tried starting it again, but it wouldnt turn over. Just "clicked" repeatedly......
Bad alternator? or bad battery?
Ive done a search, couldnt really find much that matched what I am dealing with (With the sub fading in and out)
10-02-2007, 11:42 PM
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a good way to test is start the truck and pull off the negitave terminal
if it dies instantly its the alt, if not its possibly the battery. or you could also take the alt out and take it to an autoparts store like shucks and they will test if for free
if it dies instantly its the alt, if not its possibly the battery. or you could also take the alt out and take it to an autoparts store like shucks and they will test if for free
10-03-2007, 10:09 AM
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Alternator Problems
Start the trk and ck your alt. output voltage , should be around
13.8-14.8 V , if you have an unusually high voltage when motor revved a little (above 16V) then your alt is over-charging (this would generally make your batt. boil over and hurt it badly if not quickly resolved) . If your idle voltage output of Alt. is around 14V then Alt should be Ok ( make sure to check Volts at around 2000 rpm for overcharge) , in this case battery may be bad or a very common problem is batt. terminals are dirty/corroded , or if you have installed new batt. cable ends then where the cables/wire connect to terminal ends could be dirty/corroded and or a dry/corroded Alternator Output connection with any or all of these causing reduced and or no charging voltage/current to reach the battery which would lead to eventual dis-charge of the battery completely .
If you idle the motor and check between the output of alternator and ground and the Volt. is less that 13V (generally 13.5-14.8) then I would venture to reliably say your alternator is a goner and also as pre-stated if voltage increases in the high 15's to over 16V then it is over charging (but again if that is the case you will normally see evidence of the battery boiling over at the fill caps) , Alt overcharge is typical of a shorted rectifier diode and will also lessen charge amperage leading not only to a dis-charged battery but a damaged battery from overcharging thus over-heating and boiling over .
Also as in prevoius post referencing the voltage at battery .......just remember if the alternator is bad or the connections bad then of course the battery will be discharged , so don't assume your battery is bad if voltage is low because of not getting charged , hate to see you buy a battery and then also a alternator when the new battery goes dead because of no charge reaching it !!!!
When doing this always check your connections first (then if voltage is back at battery terminals that was your problem), then determine if alternator is good (Ck output at alt. output post), if both of those are good then you can replace battery (if battery dies again after fixing any bad/corroded connections and has been re-charged) with some assurance that is the only problem
.
Hope this helps
13.8-14.8 V , if you have an unusually high voltage when motor revved a little (above 16V) then your alt is over-charging (this would generally make your batt. boil over and hurt it badly if not quickly resolved) . If your idle voltage output of Alt. is around 14V then Alt should be Ok ( make sure to check Volts at around 2000 rpm for overcharge) , in this case battery may be bad or a very common problem is batt. terminals are dirty/corroded , or if you have installed new batt. cable ends then where the cables/wire connect to terminal ends could be dirty/corroded and or a dry/corroded Alternator Output connection with any or all of these causing reduced and or no charging voltage/current to reach the battery which would lead to eventual dis-charge of the battery completely .
If you idle the motor and check between the output of alternator and ground and the Volt. is less that 13V (generally 13.5-14.8) then I would venture to reliably say your alternator is a goner and also as pre-stated if voltage increases in the high 15's to over 16V then it is over charging (but again if that is the case you will normally see evidence of the battery boiling over at the fill caps) , Alt overcharge is typical of a shorted rectifier diode and will also lessen charge amperage leading not only to a dis-charged battery but a damaged battery from overcharging thus over-heating and boiling over .
Also as in prevoius post referencing the voltage at battery .......just remember if the alternator is bad or the connections bad then of course the battery will be discharged , so don't assume your battery is bad if voltage is low because of not getting charged , hate to see you buy a battery and then also a alternator when the new battery goes dead because of no charge reaching it !!!!
When doing this always check your connections first (then if voltage is back at battery terminals that was your problem), then determine if alternator is good (Ck output at alt. output post), if both of those are good then you can replace battery (if battery dies again after fixing any bad/corroded connections and has been re-charged) with some assurance that is the only problem
.Hope this helps
Last edited by n4ynu1010; 10-04-2007 at 02:10 PM.
10-03-2007, 10:21 AM
#7
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[QUOTE=notanymore;50630360]a good way to test is start the truck and pull off the negitave terminal
This I agree is the best way to check..................If the rig stops, its the ALT. if not, have your battery checked out.
This I agree is the best way to check..................If the rig stops, its the ALT. if not, have your battery checked out.
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10-03-2007, 10:38 AM
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Alternator Problems
[quote=keithguts;50630613]I agree too as long as all the connections are good and all 12V accessories are off (ie. lights,heater fan etc.)
Last edited by n4ynu1010; 10-04-2007 at 02:10 PM.
10-03-2007, 11:48 AM
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Battery is good... took it down to the shop just to double check that its the alternator... and it is.
Thanks for the help guys.... just gotta install it tonight, should be easy tho
Thanks for the help guys.... just gotta install it tonight, should be easy tho
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