# Charging System 97 Altima



## sholex (Aug 25, 2007)

97 Altima getting/putting out only 12.2-12.6 volts at alternator I checked the 10A fuse next to the battery(ok). The plug to the altermator white wire has power, yellow/red has power when key is turned to on. I also checked all fuses inside. The battery light was on when the problem first happened, but now it want come on at all. I removed dash and checked the bulb still(the battery warning light does not come on anymore).
We replaced the alternator and fully charged the battery.
What tells the alternator to start charging?
Where does the alternator get the signal from to start charging?


Thanks


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## smj999smj (Jan 1, 2006)

Charging System Operation

When the ignition switch is in ON or START, current from the battery flows from the L terminal to the E terminal of the alternator, causing the CHARGE lamp to light up.

Then when the engine is started, the voltage output increases as the alternator rpm increases. When the voltage output becomes greater than the battery voltage, current for recharging flows from the B terminal. Simultaneously, voltage at the L terminal disappears, causing the CHARGE lamp to go out.

Note: It is possible for the alternator to charge, with the "L" circuit in operation by accelerating the engine so the RPM's are above 3,600. The current will raise high enough to complete the field current. The alternator will continue to charge until the engine is turned off. Alternator will not charge below 3,600 RPM because the field current has not been turned on by current induced by residual magnetism.
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So, to answer your question:
-the alternator begins charging when it's pulley is turned....so, anytime the engine is running, it should be charging, and the voltage output is controlled by the IC regulator inside the alternator.

First things to check:
Fuse #25 & #31 (both 10A) in the fuse panel and the 75A fusible link. Make sure the alternator is grounded. If that's all good and it's still not charging, e-mail me at [email protected] and I'll provide you with the charging system test procedure.


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