I have just reconditioned my AHGA55 alternator, during which I checked the stator and rotor for wear etc. Both are in good condition and within test parameters. Rectifier tested good with a reading of 323mv per diode set and a combined value of 741mv across B post and ground. with no flow the opposite way. However the regulator needed replacing which i have done. After rebuilding I checked the Diode value again between B post and outer case, now it reads 241mv. My understanding is that it should be between 500 and 800mv. I stripped it all down again, checking diode reading which was now 741mv. As I rebuilt the reading stayed the same until I released the regulator brushes. At which point the reading is again 241mv. As the regulator is new and should be ok, I am totally baffled and concerned that if I refit alternator in car it may do some further damage to the system. Can anyone tell me if the low reading is ok and if not why its low. Obviously I would like to get my car moving soon and buying a new alternator where i live is not an option unfortunately. The car is a Honda Stream which was rhd bought direct from Japan and converted to lefthand drive 7 years ago. The alternator is a mitsubishi model which is also fitted to the CR-V 2002. My engine is a K20A 2.0l 16vDOHC 5speed auto box. I ahve CR-V Workshop Manual which is the same as the Stream wiring etc.

 

I have not rebuilt an alternator before ,so I could not tell you what your bench readings are supposed to be, however I can tell you for a fact that once that thing is on the car it should not exceed 50mv continuously and no more than 150mv in-rush(load applied)

Anything more than 50mv continuous will cause major havoc/drivablity issues with the vehicle.....

 

Thanks for the reply,
I will have to look further into the data I have from other posts regarding rebuild and bench testing alternators. The DMM I have is just a cheap one and maybe I am misreading the reading. My basis of information is from a Honda Technician, the forward diode test between the B post and case on a new alternator gave a reading is 540 according to him plus he said the reading should not be more than 800. Not being 100% sure of how the reading was achieved or the units of reading I am assuming its mV as diode tests usual show as mV.
I was more concerned that the same test done prior to releasing the brushes was 741 and after it was 241 prior to fitting back into the car.
I was hoping that someone may be able to answer that question.
Unfortunately here rebuilding O/E alternators is our only choice as new ones are Chinese copies which invariably don't work on Hondas