[neil4224]

Hey guys,

Been driving the truck for a wile and the volt meter has been low. I have done the amp meter bypass fully as is detailed on madelectrical's site.  Here is my problem,

Showing constant 10 volts, thought wiring at voltmeter was bad. Checked all that and voltage is constant at 10 direct from battery with truck running. Come to find out I keep blowing the 30amp fuse I installed from the alternator to the positive stud on the starter relay.  I have blown 5 or so 30 amp fuses.  Will hold 11.5 to 12 volts with a rev and pop, fuse blows.  Never goes above 12volts via the gauge.  Tonight i started tinkering cleaned up a couple things and tried to go direct to battery with same 30 amp fusable link from alternator. Pop fuse still blowed. 

So I got crazy, ran a jumper wire in the fusible link and I get a constant 11.5 volts via my in dash gauge even with all my accessories active, headlights, aux fan through relay, exhaust cutouts and turn signal. Slight drop when each turns on but goes right back to 11.5.  Turn signal makes gauge pull down then jumps right back up with each pulse.  Wire sure got hotter than hell, but no smoke after about 3 minutes.  I know I need all new wire if I go direct with no fusible link. 

So here is my questions:

1. Can I run direct to battery without fusible link?  IE run new 10 gauge wire from Alternator output to battery?

2. What size fuse should I be running in the fusible link from the alternator output? 30's sure aint cutting it. Do I need to go bigger?

3. Or do I have a larger problem, like alternator putting out too much? Or voltage regulator going out?

Pics are of my jumper wire connection that gave me the constant 11.5 volts. 


 

 

[modelcitizen]

How long have you been driving truck with voltmeter at 10 volts? Is the 30 amp fuse between the alternator and battery? What amp alternator do you have on truck? With the jumper wire in place where are you getting the 11.5 volts,at the battery?Do you have a multimeter?

 

[ToxicDoc]

Your alternator likely is rated for about 60-65 amps. It will blow a 30-amp fuse easily. If you bypassed the ammeter, you can go straight to the battery with a large wire. If you connections are secure, you don't need a fuse. I have straight 2/0 wire for my 200 amp alternator.

 

[dodge82273]

x 2 from alt large terminal ( +) to battery (+) with a battery cable size wire . be sure to keep it from ever chafing and shorting out . ( heater hose ?)

now the wire that "got hotter than hell "  where again does that run ? "hotter than hell" is NO GOOD ....Fire next .

 

[86w250]

If you are working on an 81 and up truck do you need to bypass the ammeter?  I thought it was shunted?

 

[neil4224]

Your alternator likely is rated for about 60-65 amps. It will blow a 30-amp fuse easily. If you bypassed the ammeter, you can go straight to the battery with a large wire. If you connections are secure, you don't need a fuse. I have straight 2/0 wire for my 200 amp alternator.

This makes total sense now in hindsight! This is the plan I come up with last night after talking it over with my old man. Sometimes it takes actually talking and typing it out to come to the conclusion "I am a complete dumb ***".

now the wire that "got hotter than hell " where again does that run ? "hotter than hell" is NO GOOD ....Fire next .

That was the jumper wire getting hotter than hell. Haha, I knew it would. Everything else was a good temperature. Heat definitely equals fire did that once or twice before on the first truck I built.

If you are working on an 81 and up truck do you need to bypass the ammeter? I thought it was shunted?

You are correct 81 and up trucks are shunted, I have a 78/79 wiring harness in the 86 truck body/chassis. Did dash swap from a 79 so interior is 79 wiring, while firewall out is 78 wiring. What I could find at the junk yard....

How long have you been driving truck with voltmeter at 10 volts? Is the 30 amp fuse between the alternator and battery? What amp alternator do you have on truck? With the jumper wire in place where are you getting the 11.5 volts,at the battery?Do you have a multimeter?

Well been driving for about a month, mainly short trips though. I think that has been my saving grace....and a brand new battery. I don't run the truck but maybe once every couple of weeks. One long trip and found out I wasn't charging real quick.

Correct 30 amp fuse was from alternator to positive stud on starter relay. Pics above show direct to battery when I was tinkering last night. 11.5 volts is at voltmeter on dash, didn't bust out the multimeter last night, but will today to check for consistent readings. When I did this all old wiring seemed to hold appropriate voltage when I checked for 12 volt power. But I know you will get drops from the firewall connectors, just a poor design. Hence why I did the ammeter bypass. Alternator is a 60 amp.

Thanks guys for all the help. I will update my status tonight and will make sure nothing is getting hot after going directly to the battery from the alternator.

Neil

 

[Reed]

I generally ignore Madelectrical.

https://www.allpar.com/history/mopar/electrical.html

https://www.allpar.com/fix/electrical/index.html

 

[neil4224]

Well she is fixed, eliminated the fusible link, ran alternator direct to battery.  No hot wires and everything stays right at 12 volts even with all the accessories running based on my in dash gauge.  Thanks for the help everyone!

Neil

 

[ToxicDoc]

Well she is fixed, eliminated the fusible link, ran alternator direct to battery. No hot wires and everything stays right at 12 volts even with all the accessories running based on my in dash gauge. Thanks for the help everyone!

Neil

Well it's partially fixed lol. Your voltage should not go below 13.2 when engine is running.

 

[neil4224]

Haha, yeah battery was nearly dead, just did short trips last night.  Jumped right to 14 volts this morning.  A little above idle, dropped to about 13.5 ish.

 

[ToxicDoc]

Haha, yeah battery was nearly dead, just did short trips last night. Jumped right to 14 volts this morning. A little above idle, dropped to about 13.5 ish.

ok that's good. Charging system works. Battery might have had some damage, depending on how low the voltage actually got. You might want to load test it before winter

 

[daryl78powerwagon]

Check this out. Really make sure you got all your connections all good and tight.

https://ramchargercentral.com/vehicle-help/alternator-upgrade-324306/100/

 

[KurtfromLaQuinta]

I generally ignore Madelectrical.

https://www.allpar.com/history/mopar/electrical.html

https://www.allpar.com/fix/electrical/index.html

Good ol' Richard Ehrenberg... he's the best!
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