Alternator problems?

[Grumpy Old Man]

Keep it simple ,You have a 5 year old battery clean the terminals and take it to most any auto parts store they do free load checks . maybe it's just time for a new one !

 

[schmism]

just replaced the alternator in my E350 van. It was showing a half a battery light on the dash... started to come on every now and then, and over a period of 4 days got progessivly worse. (stayed on more of the time)

I watched the voltage through my scangaugeII. when the light wasnt on 14v... when it was on, 12-10 volts. I looked a local one but the parts places wanted the same price for a rebuilt china one as a i could get a rebuilt bocshe online. so i went that way. bosche one at the local parts places were 2x-3x as much as online.

 

[Soundguy]

What year vehicle? Reason I ask is they started monitoring load on the electrical system, if there is no load then they turn the duty cycle of the alternator way down to conserve fuel. It may just be something you noticed. We dont test alternators with a DVOM, you need to load it to get a real test.

an alternator with a regulator is already doing this.

when current demand is high, the alt vreg changes charge rate to keep system voltage in range.

this is NOTHING new...

 

[puckgrinder85]

Jeff Dunham - Peanut - "NYEWM" - YouTube



New(er) cars and some models are regulated externally by the PCM, which is why i asked for a model/ year as there are tons of them out there. The PCM monitors the loads and keeps fuel consumption and emissions in check, big brother doesnt want anymore power out of that engine that needs to be drawn.

 

[puckgrinder85]

My truck is a 2007 Tundra with 119k.

Original battery? Thats getting over the hill for a battery. Most last 5-7 years.

Really need to load test both to get an idea. Problems with charging generally dont jump out with a voltmeter unless its pretty obvious.

 

[Soundguy]

Original battery? Thats getting over the hill for a battery. Most last 5-7 years.

Really need to load test both to get an idea. Problems with charging generally dont jump out with a voltmeter unless its pretty obvious.

agreed.

I like to look at an ammeter as well. could be cells going bad making higher draw.. etc..

 

[murphy1244]

if this is on a generator based system, i'd say it could be worn brushes, weak springs or tall mica.. or a real cruddy vreg field circuit, perhaps with an open bias resistor.

need to know the application before going further with that thought.

MF 135 Altenator. 1967

 

[Soundguy]

external vreg?

 

[murphy1244]

external vreg?

Yes it is

 

[Soundguy]

i'd check that out.. make sure it has a good ground ref.. pry the can off and look at the contacts..