question about upgrading alt. wire

well ive gone and blown my third reman alternator on my 04 v6 explorer and i have got a high output on its way to me. it was recommended that i upgrade the charging wire but the alternator doesnt go straight to the battery. it connects to the fuse box and jumps out to the battery. can i just replace the alt wire going to the fuse box and leave the jumper to the battery? or do i have to now go from the alternator straight to the battery? any insight is greatly appreciated

Leave the factory wire in place and add an additional wire from the alternator straight to the battery

ok great thanks a lot

fuse protection

I don't know about your 2004 but on my 2000 the wire that goes from the alternator charge terminal is connected to the Mega Fuse.

Charge current passes thru the Mega Fuse to the battery positive terminal. One alternator failure mode is a shorted rectifier (diode). For that mode the Mega Fuse blows preventing the battery from being shorted to ground. My stock alternator was rated 130 amps but had a maximum output of 150 amps when load tested. The Mega Fuse was 175 amps. When I upgraded to a custom made 240 amp alternator I replaced the 175 amp Mega Fuse with a 250 amp slow blow since I could not find a 275 amp Mega Fuse.

I encourage you not to run an unfused wire from the alternator charge terminal directly to the battery. It's a fire hazard.

See Alternator upgrade - 4G, 3G large or small case?

ill take some pictures tomorrow but from what im gathering i dont have a mega fuse, there are i believe 2 fuses actually in the old wire from the alternator. my plan was to go from the new 220 amp alternator with 1/0 gauge either straight to the battery with an ANL fuse inline and then jump out to the fuse box OR go to the fuse box FIRST with the fused 1/0 gauge and then jump out to the battery with the existing wire. while on paper they both seem the same to me i might be looking at this completely wrong

safe configurations

Either of those configurations with an inline fuse will be safe. You should upgrade the battery negative terminal to ground cable. I suggest testing your new high output alternator on a tester that loads it. The "220 amp" alternator I purchased from Eagle Auto Electric for $170 only output a maximum of 160 amps - just 10 more than my stock 130 amp alternator. Many companies sell advertised "high output" alternators with only the stator coil upgraded. The rotor coil and voltage regulator must also be upgraded to provide reliable high current output. I returned mine to Eagle Auto Electric even though I had to pay shipping costs and got one custom made at a local alternator rebuild shop. The shop only could load my new alternator to 200 amps but the voltage output was still high indicating it had more capacity. The testers at discount auto stores only load the unit a small amount. Even many alternator rebuild shops don't have testers that load more than 100 amps. The shop that built my alternator rebuilds fire engine and ambulance alternators.

Mrooney322 said:

ill take some pictures tomorrow but from what im gathering i dont have a mega fuse, there are i believe 2 fuses actually in the old wire from the alternator. my plan was to go from the new 220 amp alternator with 1/0 gauge either straight to the battery with an ANL fuse inline and then jump out to the fuse box OR go to the fuse box FIRST with the fused 1/0 gauge and then jump out to the battery with the existing wire. while on paper they both seem the same to me i might be looking at this completely wrong

Click to expand...

Someone suggested increasing the wire size of the battery negative to chassis ground. I would also add another ground from the battery negative to engine block ground. google "the big 3" that is the three wires you should upgrade while increasing the electrical equipment on the vehicle.
I would add your 1/0 straight from the alt pos to batt pos though. Make sure you fuse it but I wouldn't bother running it back through the fuse box and then back to the battery. that just sounds like too much wire and too much work.

I would Just run a fused wire straight from the alt to battery , add a ground to frame and from amp or amps straight to the frame , if your using 1/0 make sure your lugs fit before your crimp or solder , Some lugs have a hard time fitting the back of the alt without some plastic persuasion .

thanks for the input, i ended up just running the 1/0 to the fuse box, overall much simpler and cleaner than trying to go straight to the battery, i plan on upgrading the grounds when funds allow. i have a thread in the 3rd gen modified section outlining what i used and how i ran the wire

http://www.explorerforum.com/forums/showthread.php?t=406467