Alternator excite wire

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Vodka0tter

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I installed an analog gauge cluster, removing the OEM cluster. Naturally my alternator did not charge as it did not receive a signal from the dash bulb (excite wire). I am considering just putting a resistor inline as opposed to re-connecting to a warning bulb (still kinda on the fence) but am not sure what ohm/watt I should select. Need some advice from those smart electrical boys please.
 

TheAutumnWind

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I installed an analog gauge cluster, removing the OEM cluster. Naturally my alternator did not charge as it did not receive a signal from the dash bulb (excite wire). I am considering just putting a resistor inline as opposed to re-connecting to a warning bulb (still kinda on the fence) but am not sure what ohm/watt I should select. Need some advice from those smart electrical boys please.
What is your alternator setup?

Need more info on your truck.

Ad244s require 5v iirc?
 

DallasTahoe

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What is your alternator setup?

Need more info on your truck.

Ad244s require 5v iirc?

I’ve got an ad244 and it’s acting dumb, used to charge at about 13.9 now it stays below 13.3 if there’s very little draw, once my fans kick in it drops to about 12.4-12.6


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Dubs

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I just hooked the excite wire to a key on hot wire. Works great. 14.4v no issues. Been like that for about 8mo.
 

someotherguy

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I’ve got an ad244 and it’s acting dumb, used to charge at about 13.9 now it stays below 13.3 if there’s very little draw, once my fans kick in it drops to about 12.4-12.6


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Only 13.9? Should be right at 14.1 when operating properly.

Anyway I've never done it, but sources around the web seem to indicate 270ohm-330ohm resistor will do the trick. Wattage requirement is pretty low, like .5w or so. I'd pay close attention to whether or not your setup is working correctly before buttoning everything up as you don't want a hot resistor buried in your dash in the event it's not behaving as expected. In other words, your charge lamp would normally only come on just during bulb check (key on/engine off) then extinguish after the alternator starts charging. BUT, if the alternator fails, in your new situation you wouldn't have the lamp glowing but the resistor getting hot next to whatever it's touching...(if my brain is working correctly after a 14+ hr shift, that is.)

Lots of discussion on this subject in various places but most vehicle charging systems (even bikes) operate pretty much the same way, though a lot of the posts are people subbing an LED for the original incandescent bulb, instead of omitting the light entirely. That brings a tiny bit more complexity as a separate resistor is needed to drop voltage to the LED to prevent burning it out.

Richard
 

Vodka0tter

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Only 13.9? Should be right at 14.1 when operating properly.

Anyway I've never done it, but sources around the web seem to indicate 270ohm-330ohm resistor will do the trick. Wattage requirement is pretty low, like .5w or so. I'd pay close attention to whether or not your setup is working correctly before buttoning everything up as you don't want a hot resistor buried in your dash in the event it's not behaving as expected. In other words, your charge lamp would normally only come on just during bulb check (key on/engine off) then extinguish after the alternator starts charging. BUT, if the alternator fails, in your new situation you wouldn't have the lamp glowing but the resistor getting hot next to whatever it's touching...(if my brain is working correctly after a 14+ hr shift, that is.)

Lots of discussion on this subject in various places but most vehicle charging systems (even bikes) operate pretty much the same way, though a lot of the posts are people subbing an LED for the original incandescent bulb, instead of omitting the light entirely. That brings a tiny bit more complexity as a separate resistor is needed to drop voltage to the LED to prevent burning it out.

Richard


humm.. you make a good point about super heating the resistor when the Alt fails. Had not thought of that.

I think I'll just wire an idiot light to the new cluster and call it good.

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Frank Compagnon

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I had to install a new alternator on my 88 GMC , and install a single wire one, didnt do anything with the other wires and it charges fine, just taped them up.
 

DallasTahoe

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Ok so I don’t know why I didn’t think of this before, check your alternator to battery cable. I just checked mine and this was the second time I’ve replaced it, it gets burned! Haven’t figured out how or why just yet but this is the second time I’ve replaced it. I’m only running a 145 amp alternator and 0/1 gauge cable with dual batteries here is what it looked like
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When checking voltage from the alternator to the mega fuse where it connects to the battery I was seeing about a half to 3/4 volt drop, way too much for a 16in length of cable.... just an fyi


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Kran

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Ok so I don’t know why I didn’t think of this before, check your alternator to battery cable. I just checked mine and this was the second time I’ve replaced it, it gets burned! Haven’t figured out how or why just yet but this is the second time I’ve replaced it. I’m only running a 145 amp alternator and 0/1 gauge cable with dual batteries here is what it looked like
When checking voltage from the alternator to the mega fuse where it connects to the battery I was seeing about a half to 3/4 volt drop, way too much for a 16in length of cable.... just an fyi


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your crimp is NOT good. thats why you've burned up 300 amp capable cable. you need at minimum a hammer crimper. better yet a hydraulic crimper, or fill the lug with solder and dunk the wire in and let the strands soak.
 
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