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Topic
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Hi Everyone.
Sure hope somebody can help.
My Maxima se is over charging to the point of FRIED battery. I took the alternator off and had it checked and it checks ok. The old battery was fried and replaced with new one. Still the charging system will not open when charge is sufficient. I have checked the plugs at the battery and cannot see any problems. Looking at the schematic for this car’s charging system I cannot see anything that would make this happen. I have been trying to solve this problem for 2 weeks and still I am at a loss. It’s going to take someone smarter than I. ANY TAKER’S
Thanks 🙁
Mary
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Replies
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If the system is over charging.I would suspect the alternator.
The alternator has a built in regulator. see if this chart helps.Did you check the alternators voltage output? If not, you’ll need to in order to verify the overcharging issue. More info can be found here.
http://www.ericthecarguy.com/faq/solving-automotive-electrical-problems
How has this overcharging been determined? With a voltmeter? Was this checked at the back of the alternator or at the battery terminals?
A failed fusible link between the alternator and battery can cause an alternator to run amok but will not fry the battery.
These may help a bit.
It looks like the Alternator uses the S terminal as the regulator’s reference line. If there is a significant voltage drop prior to that terminal, the regulator will think the batteries voltage is low and overcharge it.
The only real way to test an alternator is to put an ammeter on the thick alternator to battery wire. In the old days you had to unhook this wire to insert an ammeter, but now there are clamp-on magnetic ammeters.
If the alternator and voltage regulator are working correctly, you should see like a 10 to 30 amp charging current right after starting the engine, dropping off to maybe 3 amps after a minute. And that current level should not change a bit as you rev the engine. If the current zooms up when you rev the engine, the voltage regulator is bad.
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