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HybridZ

Alternator overcharging!!


softopz

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Hey guys basically the subjects explains whats happening, however before this happened I upgraded to the zx internally regulated. The car is a 240z With l28et I followed the write up but it didnt go well. I removed the external regulator and spliced the white black with black white wire with a diode so it doesnt feedback and leave the car on. I believe thats the L terminal which is the Base of "T" shape connector. On my alternator its not labelled L I have F and N anywho it should be still the same cause the alternator is from a zx and starts with l60.... moving on . The S terminal which is the top of the T connector is suppose to be spliced yellow to white wire (which is a 12 v always on) this is the problem here that wire got really hot I turned it off. I re read the article for the swap thats suppose to go straight to the batterey to provide feedbakc to alternator. With that wire un plugged I can hear the alternator whine and charge except its like overcharging Iam getting like 13-16 v at idle and if I rev it up it even goes to 17 18 !!! my battery is going to explode cause I hear squeeling it out acide :S AND if I leave that wire in it gets warm reaaaal fast and burn I tried another another wire that goes straight to batterey and same thing happens. Iam really stumped at this point. Any advice guys?

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You may want to get an independent confirmation that the alternator is overcharging. Places like Autozone and Pep Boys provide free bench-testing for components like alternators, starters, etc.

 

Next, you mentioned that you removed the external regulator.....but are you sure that your new alternator is internally-regulated, and if so, is it working correctly? The bench-testing I mentioned above will include testing the regulator.

 

Finally, are your yellow and white wires large enough to carry high amps? (I think 12-gauge is the norm for the charging wire leaving the alternator.) Also, are all the connections clean and corrosion free? Finally, are you sure that there are no shorts in the system? If you answered no to any of the above, that may be the root cause of your problem.

 

Hope this helps. Be sure to post your results and let us know how it goes. Good luck and happy motoring.

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My advice is to put it back how it was unless you had a problem with the stock charging system. I did the GM 100 amp internally regulated alternator swap on my 77 Z and had a massive failure. It was not the alternator or MY re-wiring, it was a failure with the stock wiring. When you upgrade the charging system in an old car without upgrading the wiring the extra amperage will find the weak links in the system. I have not read the write up, but I would check the wiring diagram and make sure the wires make sense. Don't "assume" that the wiring is correct, especially when it comes to your charging system. It took me a week of tearing into wiring to figure out that Datsun's version of a splice is to wrap one wire around a bare spot in another wire, cover it with black tape and then stuff it in a harness. After 20 years the wires corrode and you don't have good continuity. Luckily the charging systems aren't complicated...look at your diagram, if you can't read it leave it alone.

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