Voltage question...

[ILikeMy240sx]

My car is a 96 240sx with about 80k miles...

Recently my voltmeter(autogauge) shows a low voltage than it's supposed to. When I start the car it's a bit over 14 but after driving around for a bit it gets low to around 13~13.5... sometimes it fluctuates a little in that range.

When i turn off the engine and put the key in "On" position the voltage drops to around 12v.. which used to be around 13 when the engine was off...

What could be wrong with my electrical system?

[PMan_S13]

a battery running out of juice comes to mind...

[ILikeMy240sx]

changed the battery about less than a year ago... maybe needs charging?

[s13sr20chris]

voltage with engine running is all about the alternator. cold motor=high idle and alt charging good. warm motor=lower idle and alt charging not quite as well. that is typical on older alternators.

[ILikeMy240sx]

hmmm Now I think about it, when I am on the highway at 3500rpm or so the voltage seems fine... But when Im driving in downtown or something like that it's usually low...

Does this mean I have to change the alternator?

[p00t]

as long as the cars running fine and starts fine then all is well. Your alt is obviously older and weaker but its still doing its job.

with the engine off the battery should be 12-12.3v or so.

with the car running the alt should be producing 13+ volts.

Its good that your keeping your car in close check! Once your alt output is below 13v and your car just isnt charging the battery well anymore youll know what the problem is.

[ILikeMy240sx]

Thank you for all your replies. They are very helpful.

The car is running fine and starts fine... The FSM said that the alt shold be productin 14.1~14.6 V so.. I was a bit worried but I guess the car's runing fine it's just an old alternator i guess...

Will it eventually reach that point where the alternator won't charge the battery anymore? Maybe this is the beginning step...

Oh BTW, what will hapen when the alternator is not charging the battery anymore?

[p00t]

Thank you for all your replies. They are very helpful.

The car is running fine and starts fine... The FSM said that the alt shold be productin 14.1~14.6 V so.. I was a bit worried but I guess the car's runing fine it's just an old alternator i guess...

Will it eventually reach that point where the alternator won't charge the battery anymore? Maybe this is the beginning step...

Oh BTW, what will hapen when the alternator is not charging the battery anymore?

it could be the beginning step... but dont waste money on parts untill they are actually going t cause a problem. Alternators are so random its rediculous.

when it doesnt charge the battery anymore? hmmm silly question... what happens to people with dead/weak batteries?

[ILikeMy240sx]

ha