1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

Testing Alternator Question

Thread Tools
 
Search this Thread
 
Old 05-09-18, 10:31 AM
  #1  
Junior Member
Thread Starter
 
A12Spitfire's Avatar
 
Join Date: Dec 2015
Location: San Francisco
Posts: 41
Received 0 Likes on 0 Posts
Smile Testing Alternator Question

Hey guys,

Quick question, I have looked in the manual and did a couple of searches here on the forum and am not really finding what I am looking for. I believe my alternator is no longer working but before I go buy another one is there an easy way to test it? I have the volt/amp meter that I can use to test. I have an '85 12A.

Any advice would be greatly appreciated.

Thanks
Bill
Old 05-09-18, 02:13 PM
  #2  
Out In the Barn


iTrader: (9)
 
KansasCityREPU's Avatar
 
Join Date: Mar 2005
Location: KC
Posts: 6,050
Received 1,013 Likes on 799 Posts
Take the alt off and take it to the auto parts store. They will load test it.

or do this. It from Chris Fix.

http://ttps://www.youtube.com/watch?v=LGB6ZEjGm7Q
Old 05-09-18, 08:40 PM
  #3  
I have a rotary addiction

iTrader: (18)
 
NCross's Avatar
 
Join Date: Jun 2006
Location: Columbia, Tennessee
Posts: 4,815
Received 23 Likes on 22 Posts
Idle the car with all electrical accessories at full (bright lights on, blower on high, radio on, maybe even kick on the hazards for max electrical load. Stick a volt meter on the battery + and - and you should see a minimum of 13 volts for an old worn out alternator. Preferred is 13.5-14 volts.
Old 05-10-18, 02:04 AM
  #4  
84SE-EGI helpy-helperton

 
LongDuck's Avatar
 
Join Date: Oct 2002
Location: Phoenix, AZ
Posts: 3,312
Received 357 Likes on 248 Posts
One of the things about Alternators is DO NOT EVER SPIN IT when it's not hooked up to the car electrical system. The voltage diodes in the Regulator will be blown and that Alternator will be dead. Aside from that, the best test is to take it to any auto parts store for load testing. They'll be able to tell you exactly what the output amperage is at specified RPM, and that's everything you need to know if it's in good working order.
Old 05-10-18, 09:57 AM
  #5  
Junior Member
Thread Starter
 
A12Spitfire's Avatar
 
Join Date: Dec 2015
Location: San Francisco
Posts: 41
Received 0 Likes on 0 Posts
This is great info guys. Thank you. One last question:

How can I tell if my alternator needs an external regulator? I have had the car 2 years and it did not have one and I never had any issues. I believe the motor is from an '85 Rx7. Is there a way I can tell if I need an external regulator from look at the outside of the alternator?

Thanks again!
Bill
Old 05-10-18, 11:16 AM
  #6  
Out In the Barn


iTrader: (9)
 
KansasCityREPU's Avatar
 
Join Date: Mar 2005
Location: KC
Posts: 6,050
Received 1,013 Likes on 799 Posts
All RX-7's after 1980 have the regulator built into the alternator.
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
daem0n
3rd Generation Specific (1993-2002)
7
05-08-07 01:39 AM
evilfocus
2nd Generation Specific (1986-1992)
5
03-30-06 04:46 PM
1987RX7guy
2nd Generation Specific (1986-1992)
162
02-24-04 05:22 PM
Center of The Universe
2nd Generation Specific (1986-1992)
12
04-14-03 07:12 PM
JONSKI
General Rotary Tech Support
5
08-30-02 04:06 PM



Quick Reply: Testing Alternator Question



All times are GMT -5. The time now is 02:35 PM.