Alternator Upgrade Due To Electric Fan

Over about 20 mph your fan can't draw air faster then its being pushed through the air stream by your forward movement. I put an electric fan on the wifes 67 Mustang 200L6 and it almost never came on unless the car was sitting still. Had the temp adjusted to come on a 190 degrees with a 180 degree thermostat.

 

Here is the setup I like.

 

That 15 ohm resistance can be replaced by a diode, which is what I do. Wire size very important! Solder in diode with cathode facing alternator. Then use a piece of shrink to cover.

 

Why would you not want a charge light?

 

I already have a Voltmeter in dash to see what I got, so a bulb would be over kill.

Is the diode really needed if you have #1connected to ACC on your starter switch? For the sensing or #2 post, shouldn't you run that someplace other than the hot lead on the alternator? If you are getting a load on the other side of the battery, isn't that what you want the alternator to produce electricity for?

Thank you for posting the diagram and pics, it really shows just what to do and how to do it. Thanks!

 

From what I remember about a charge light when I worked on cars for a living 30 years ago. Most vehicles had AMP guage, so it could be difficult for the average person to tell what was happening with needle pointing up. I think the Volt meter is way better if you know where it should be indicating. Not that there aren't good opinions on both sides.

From what I understand it is nessisary to use either the 15 ohm resistor or the diode. The silicon diode provides the resistance and also blocks reverse current. You can get them at radio shack cheap. If they don't have the exact number listed, any larger rectifier diode will work. The cathode end is the band and blocks current flow from alternator to the switched source(key switch). And allows only current flow from switched source (key switch) towards alternator, which energizes it. That's my two cents. Let me know if you have any questions.

Cole

 

use an light and hang it where you cant see it 194 bulbs and sockets are plentiful.

 

Been a little late on this post, but i burn up a 10si and 12si in 3 years. Finaly end up using a cs144, way better amp at idle, been running it for a year without any issus. Almost the same dimension as the 12si and you can buy an adapter for wiring it with only two wire, dont need to mess with diode or anything.

 

Finally am home long enough to put a digital voltmeter from POS terminal to ground with fan on and lights on this morning. Its bad. At idle it isn't charging at all, well maybe a little bit. As I watch the meter, the battery is discharging... Give it throttle to over 1K and its right up there, charging at 14.5, below 1k and its not even remotely adequate above ignition requirements.

This is a reman alternator and a new solid state regulator. One of the 2 or both are bad. I will not replace them with the same stuff, but will go to a 94 amp 12 SI alternator when I get a chance. Its fine for daylight driving, but I will eventually get stranded at night and or ruin my battery before then.

 

Just bought this
More Information for REMY 202661

 

Was there any detail available on that 94 Amp as far as Amps at various RPM's?

 

No. That may be an issue, but Patrick says his is no problem. Its 67 bucks with a 20 dollar core. Not a lot of money to see if I can remedy the problem.

 

Has i said, 10si and 12si don't have suffisant output power.

Here picture of rpm/amp for the 10si,12si and cs144.

At 2000 rpm on the alternator here the spec
10si: 30 amp
12si :50 amp
cs144: 100 amp

if you have place for a 12si you have place for a cs144 and they are almost the same price.

 

I went to a local place that built an alternator to your specifications, $1 per amp. The budget was a little tight at the time but I was able to get 120. I also run dual batteries.

 

Thank you for the nice graphs.
I am not looking for peak output, but output at idle. As your graph shows, the output near idle for the CS144 VS the 12SI rated at 94 amps, shows the 12 SI at a bit better output at lower shaft RPM for the alternator.

I am also not convinced that the 10DN alternator is really a 63 amp unit or that the regulator is working as it should.

 

Dont forget that idle rpm of engine is not the idle rpm for alternator. The pulley rpm of the alternator is 3-4 time faster than engine rpm, that's why i was refering to 2000 rpm. I realy suggest going with the cs144, did the 12si as i said and problem come back fast, i was having a 12.5v at idle with only fan on, when you put headlight, heater you kill the alternator. With my cs144 with everything on, still have a strong 14v,

 

Thank you for your suggestion. If this 12SI doesnt work out, I will go to the CS144. I have already ordered the 12 SI.

 

I hope so. I am going to get my battery load tested here in a hot second. Its less than 12 volts on start up now and takes a good couple of seconds above 1200RPM to bring it up to charge. Either the alternator is taking a dump, I have a voltage leak, unlikely, or the battery is done. Its over 80 today..