charging problem now

[BACKSLAP]

charging system problem

have 3 wire alternator. checked the diagram and wired it like this:

main wire - to battery of course

pigtail, twisted and soldered both wires together, put a 4.7ohm resistor in series (same as the cluster bulb needed to charge), then put it to accessory power.

i rebuilt my own alternator and tried 2 others, cannot charge at idle only if it races at least to 2000 rpm will it charge.

i have march perf serp. belt setup on there for electric water pump, pulley sizes all match correctly.

physically it seems like it is spinning too slowly but cant be cure, rpm is near 850 pretty much where i want it but no chargeing at idle or off idle until 2000 rpm is reached?

anyone??

 

[megaladon6]

if you rev it to 2000 then let it go back to idle, does it keep charging? or do you have to keep it over 2k?

 

[BACKSLAP]

DOESNT stay charging must keep it up there , kinda sucks
im trying to find a smaller pulley for this thing that looks good and is 6 groove, gotta match one up at the parts store im gonna try that first.

unless someone sees im doing something wrong

 

[megaladon6]

do you know the designation for the alternator or the original application?

 

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yes out of a 75 impala im told. this race car crap sucks.

 

[megaladon6]

i just did a quick search and what i'm finding matches what i was thinking, obviously the main line goes to the battery, then the larger of the 2 wires goes to the output terminal of the alternator, and the other wire goes through the resistor/light to accessory power.

 

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I HAVE IT wired exactly like that no voltage drops, etc.. i put on a smaller pulley from a late 80's fwd gm car, worked better, now at idle i am getting 12.8v, hardly even charging, then when i rev it or drive it now at least its going into the mid 13.5 volt range, better than before but still a problem, please at this point my headaches are bad man, any other similar problems out there?

thanks for the help so far.

 

[megaladon6]

pigtail, twisted and soldered both wires together, put a 4.7ohm resistor in series (same as the cluster bulb needed to charge), then put it to accessory power.

then the larger of the 2 wires goes to the output terminal of the alternator, and the other wire goes through the resistor/light to accessory power.

just double checking here, but did you change it from the first way?

 

[BACKSLAP]

ah ha yes, i wired it 2 different ways, tried both,

I GOT THE PROBLEM

this morning i checked the amperage of this circuit it was 78 amp alternator, dammit, the fans i used 1 from a 2001 chrysler 300m and 1 from a 2001 nissan maxima, fit perfect but combined draw a total of 92 amps, disconnected the fans and instantly charged perfect.

now i found a 120 amp alternator from a caddilac still 3 wire, had to just spin the housing, and now i need to find out which is the best most highest cfm fan i can get without passing a 40 amp draw.


mint, thanks everyone for trying to help and brainstorming, thanks alot very much!!!!

lesson learned, back to basics

btw, in the process found a blown fuse in my multimeter - lol

 

[megaladon6]

i forgot that you said, in the other post, that the fans ran all the time DOH!!!