alternator testing

[Kyle]

driving home in the dark last night with just the normal lights, no fogs or anything that didnt come standard on the truck my voltmeter was reading like 12-13 volts and at some points even less like the alternator wasnt charging the battery correctly. but the alternator is only 6 months old.... i tried checkin the alternator output with the truck on and all the lights on by testing the pole to a ground with a voltmeter and it didnt seem to register anything but i touched it to the battery ground and i got just over 12, but did i do that wrong? was that just the battery's current?

is it possibly that ive fried it prematurely because i do draw alot of power sometimes with all my extra offroad lighting(but i dont ever really run them that often)?

[Disturban]

Just take a volt meter and connect it to + and - on the battery, when the alternator kicks on you should have 14.3 volts, if you are down in the 12 to 13 volt range then chances are you are going to need a new one.

Autozone can also test them for free while it is in your car, their little machine will put a load on the electrical system forcing the alt to kick on and then tell you if it is good or bad.

[Kyle]

i started it up this mornin and it was puttin out a lil more off the bat than it did last night by the dash guage. i checked the battery before it was on and it was at about 12.4~.5 and when i started it up it was around ~14 but when i put it under full load it was like 13.... and when i shut it off after a couple mins of run time i touched the alternator and it was already hot while all the other pulleys werent

i guess ill be stoppin by autozone on my way into work then.... at least its keeping a charge in the battery...

[Jjay78]

hopefully ya still got a warrenty on it man, might try stepping up to the next output level

[Kyle]

hopefully ya still got a warrenty on it man, might try stepping up to the next output level

no it didnt come with a warranty....

got it tested and it was runnin better than the night before charging wise. it WAS putting out lower voltage from a regular one but still putting out enough to keep the battery charged. its like on the verge of being no good

this is what i was thinking about upgrading to: http://www.summitracing.com/parts/PWM-47861/

[J.C.]

i know on older cars you can unhook the pos cable when its runnin and if it stays runnin it works. if it dies its bad. not sure about doin it with newer vehicles with computers...

[Disturban]

I got a Duralast Gold alternator at Autozone for the wifes truck about 3yrs ago and have had zero problems with it...nice thing is they come with a life time warranty so if we ever do have a problem with it we get a new one for free, something you might want to look into?

[Kyle]

I got a Duralast Gold alternator at Autozone for the wifes truck about 3yrs ago and have had zero problems with it...nice thing is they come with a life time warranty so if we ever do have a problem with it we get a new one for free, something you might want to look into?

yea i had thought about it.... but i do have ALOT of electronics drawing juice in my truck and its only gonna get more and worse so i figured i might as well just up to more amps

[rangerwheelinmike]

i know on older cars you can unhook the pos cable when its runnin and if it stays runnin it works. if it dies its bad. not sure about doin it with newer vehicles with computers...

try that that works with tbi if its good it will run motor if not it will die

[Kyle]

i know on older cars you can unhook the pos cable when its runnin and if it stays runnin it works. if it dies its bad. not sure about doin it with newer vehicles with computers...

try that that works with tbi if its good it will run motor if not it will die

well i know it wont die cuz the alternator is puttin out just enough to keep the battery charged somehow. and its been fluctuating for how many volts it puts out each time i run the truck.... its like it has a mind of its own!!

[Disturban]

i know on older cars you can unhook the pos cable when its runnin and if it stays runnin it works. if it dies its bad. not sure about doin it with newer vehicles with computers...

try that that works with tbi if its good it will run motor if not it will die

well i know it wont die cuz the alternator is puttin out just enough to keep the battery charged somehow. and its been fluctuating for how many volts it puts out each time i run the truck.... its like it has a mind of its own!!

That is because the voltage regulator is going bad in it.

[Kyle]

i dropped a brand new powermaster 140 amp alternator in today. did great for a while but then it started losing volts again. its still keeping everything charged but shouldnt my voltmeter always be at 14 anyways? could i be lookin at the alernator not be grounded well enough? or the alt to battery cable getting old and not being able to handle the extra draw properly?

[Disturban]

i dropped a brand new powermaster 140 amp alternator in today. did great for a while but then it started losing volts again. its still keeping everything charged but shouldnt my voltmeter always be at 14 anyways? could i be lookin at the alernator not be grounded well enough? or the alt to battery cable getting old and not being able to handle the extra draw properly?

You will only see 14.4 volts when the alternator is on...it is a good idea though to clean all your contacts and replace any damaged or old wires, clean your grounds real good!

[old school truck dude]

With all the extra electricals, you should probably hook up some really fat ground straps from frame to body to motor to battery, use an extra one for the bed to frame,  and also replace your main hot wire off the back of the alternator with a big fatty, and also run another big fatty directly from the battery to the alternator. Use good quality CRIMP connectors. NEVER use solder terminals, if they get hot the wire can slip out and short, causin a roarin fire and mega damage. Electric can do some strange stuff when it encounters resistance in its constant search for a ground. The factory wires and ground straps are not all that great to begin with, and when you add the extras its too much.  For ground straps, I recommend battery cables with a good copper lug on each end, take a punch and put a good ding in it so it wont slip out if it gets hot. For main hot wire direct from the alt to the battery Id use 6-8 guage copper

[Kyle]

With all the extra electricals, you should probably hook up some really fat ground straps from frame to body to motor to battery, use an extra one for the bed to frame,  and also replace your main hot wire off the back of the alternator with a big fatty, and also run another big fatty directly from the battery to the alternator. Use good quality CRIMP connectors. NEVER use solder terminals, if they get hot the wire can slip out and short, causin a roarin fire and mega damage. Electric can do some strange stuff when it encounters resistance in its constant search for a ground. The factory wires and ground straps are not all that great to begin with, and when you add the extras its too much.  For ground straps, I recommend battery cables with a good copper lug on each end, take a punch and put a good ding in it so it wont slip out if it gets hot. For main hot wire direct from the alt to the battery Id use 6-8 guage copper

thats where i was thinkin biout goin next. grounding the alternator with a seperate wire along with it grounded by its bracketry. wire from alt to battery. then motor to frame. all bein done with 2 guage

[old school truck dude]

Yup, that and the fat wire direct off the alt to batt is gonna help alot