Small electrical meltdown

[diesel_lv]

Finally finished wiring the 3rd set of electric fans in '67 Coronet. My electric setup is, serpentine pulley w '95 Durango 140 amp alternator. 4 ga wire to starter relay, factory positive cable from relay to battery. Started and everything worked great, let it run for about 15 minutes to make sure fans kicked on at appropriate temp. And when a/c switched on. All good. Came back an hour later to go get some dinner. Start car and turn on a/c and headlights. Notice voltage at idle is very low, 12 volts. Normally w the previous 2 fan setups it would still idle at 14+ volts. Rev engine a little and volts come up. Then I notice voltage dropping down to 11.8 and I immediately turn around and pull back in garage n shut off car. Come out this morning and see wire at alternator had melted through a little. Wires at starter relay all melted. Is this an issue w the relay not designed for this type of amperage draw? I've got electric in-tank fuel pump, fuel injection, 2 e-fans drawing 35 amps each on startup and 22-25 constant, a/c. The fans are wired w 10ga positive n negative w 70amp relays and 40 amp circuit breakers. Fuel pump wired the same. All direct to battery. Am I missing something? Should I wire alternator directly to battery then from battery to relay?

Thanks in advance.

 

[72sunroof]

Finally finished wiring the 3rd set of electric fans in '67 Coronet. My electric setup is, serpentine pulley w '95 Durango 140 amp alternator. 4 ga wire to starter relay, factory positive cable from relay to battery. Started and everything worked great, let it run for about 15 minutes to make sure fans kicked on at appropriate temp. And when a/c switched on. All good. Came back an hour later to go get some dinner. Start car and turn on a/c and headlights. Notice voltage at idle is very low, 12 volts. Normally w the previous 2 fan setups it would still idle at 14+ volts. Rev engine a little and volts come up. Then I notice voltage dropping down to 11.8 and I immediately turn around and pull back in garage n shut off car. Come out this morning and see wire at alternator had melted through a little. Wires at starter relay all melted. Is this an issue w the relay not designed for this type of amperage draw? I've got electric in-tank fuel pump, fuel injection, 2 e-fans drawing 35 amps each on startup and 22-25 constant, a/c. The fans are wired w 10ga positive n negative w 70amp relays and 40 amp circuit breakers. Fuel pump wired the same. All direct to battery. Am I missing something? Should I wire alternator directly to battery then from battery to relay?

Thanks in advance.

You definitely have way to much amperage, is there a valid reason why you need a 3rd fan. 2 smalls or one big should be enough, honestly if it is running that hot you have other issues.
Try going led on the headlights you lose a bunch of draw from that.

As far as your wire melting your wire, it is too small for the draw. Here is a calculator you need 2 or 1 gauge for that level of draw.
https://www.wirebarn.com/Wire-Calculator-_ep_41.html

 

[diesel_lv]

You definitely have way to much amperage, is there a valid reason why you need a 3rd fan. 2 smalls or one big should be enough, honestly if it is running that hot you have other issues.
Try going led on the headlights you lose a bunch of draw from that.

As far as your wire melting your wire, it is too small for the draw. Here is a calculator you need 2 or 1 gauge for that level of draw.
https://www.wirebarn.com/Wire-Calculator-_ep_41.html

Sorry for the misunderstanding, I didn't mean 3 fans, I meant 3rd set. I went through 2 other dual set ups that didn't work. This set pulls much more amps and more cfm and seemed to work. I thought 4ga would be good for the constant load, up to 75amp constant on 4ga, but once I tear apart the harness to assess actual damage, will be going to 2ga. My idea is to run straight from alternator to battery, then run from battery to starter relay. I have a voltage gauge instead of amp meter and did the Mad electronics wiring upgrade. This way any heavy draw is directly from the battery and not passing "through" other items.

 

[diesel_lv]

Well, removed wire from alternator to starter relay. Ran 2 ga wire from alternator straight to battery, 3.5'. Cut out melted wires at bulkhead, 3 wires, and 3 wires at relay. All connected up w freshly charged battery. Start and voltage jumps up to 15.4 then slowly drops to 14.4. Turn on a/c and fans come on. Turn off a/c and fans off until engine gets to preset 190° then fans on. Turn off, then restart, all good. Go for test drive n all good. Stop for gas, go to start and cranks but FI handheld goes blank and won't start. That usually means low voltage. Wait about 10 minutes and it barely starts. Drive home but now voltage only 13.2. Checked all wires, none loose, none melted or hot. So now I'm wondering if it's voltage regulator which is preset at 14.3 or alternator.