Replacing factory battery cables

[Drunner97]

That seems like a nice upgrade! Where did you get the 240a alternator from, and how much did you end up paying for it?

When you did your big 3, what gauge cable did you end up using? I think the factory cable is 2 gauge...

My electrical system seems fine, but if I can reduce the voltage drop by a couple tenths of a volt ill consider doing it.

Toyota 4Runner High Output Alternators

I paid right around 430ish after taxes, free shipping. They are located out in Riverside, Yucaipa I think, but I wasn't in a hurry. Ended up still being 1 day shipping. Ordered in the morning, had it next day.

1/0 for the Big 3 upgrade and 1/0 for my dual battery setup. I have virtually no voltage loss between both batteries when they're connected except for when my house battery is low. It seems with a simple isolator setup the starting battery (closest to the alternator) will always have a higher voltage than the house battery when the house battery is low. I usually see around 13.8 on starting battery and 13.6 on house when the house needs a charge, otherwise they're typically the same at 13.8-14.0.

 

[Bumbo]

Perfect, thanks for that. I actually have some 1/0 laying around I can use up.

Did you do the cable and alternator at the same time? Im just curious how the big 3 upgrade helped the voltage drop with the OEM alternator.

 

[Drunner97]

Perfect, thanks for that. I actually have some 1/0 laying around I can use up.

Did you do the cable and alternator at the same time? Im just curious how the big 3 upgrade helped the voltage drop with the OEM alternator.

With stock electrical should pretty much eliminate it I would imagine. I did do both at the same time because I was having issues keeping my house battery charged with my fridge running full blast, off road lights, and a/c running in 80-100 degree heat while off road at idle and starting/stopping with a big group over 2 days so I was trying to fix it before the next camping trip I had planned.

 

[Bumbo]

With stock electrical should pretty much eliminate it I would imagine. I did do both at the same time because I was having issues keeping my house battery charged with my fridge running full blast, off road lights, and a/c running in 80-100 degree heat while off road at idle and starting/stopping with a big group over 2 days so I was trying to fix it before the next camping trip I had planned.

Nice, perhaps I should look into an alternator as my electrical load increases... Right now I have a couple light bars, fridge, ham radio, along with a couple plug in accessories but I still have enough overhead for charging...

The issue I am trying to work out has more to do with the voltage my ACR is reading... I installed the ACR on the other size of the engine bay so I am seeing some voltage drop from the distance, and on hot days and when the starter battery is full the ACR takes too long to combine.

If I can rescue a couple tenths of a volt via larger wire my problems should go away. That said, I only used 4 AWG for my house battery, but based on my load figures it should have been more than sufficient plus there is no voltage drop until it combines which is the issue I am working on.

I also checked after it was installed with a DC clamp style amp meter... and it peaks at 77 amps when it combines from a 11.7v LVD cut-off, and levels out to about 33-35 amps after it equalizes for about 20 seconds.

 

[Drunner97]

Nice, perhaps I should look into an alternator as my electrical load increases... Right now I have a couple light bars, fridge, ham radio, along with a couple plug in accessories but I still have enough overhead for charging...

The issue I am trying to work out has more to do with the voltage my ACR is reading... I installed the ACR on the other size of the engine bay so I am seeing some voltage drop from the distance, and on hot days and when the starter battery is full the ACR takes too long to combine.

If I can rescue a couple tenths of a volt via larger wire my problems should go away. That said, I only used 4 AWG for my house battery, but based on my load figures it should have been more than sufficient plus there is no voltage drop until it combines which is the issue I am working on.

I used 4g originally for my dual battery setup too and was running into the problem where my starting battery was getting 13.8 and house battery was getting 13.1. That was also part of my problem and why I upgraded everything to 1/0.

 

[Bumbo]

I used 4g originally for my dual battery setup too and was running into the problem where my starting battery was getting 13.8 and house battery was getting 13.1. That was also part of my problem and why I upgraded everything to 1/0.

Then you definitely have more electrical load than I have right now... I dont get that steep of a voltage drop across my 4g cable... ill double check tonight with me meter.

But as I mentioned above, I dont see a voltage drop before it combines... my problem is getting it to combine sooner than later.

 

[Drunner97]

Then you definitely have more electrical load than I have right now... I dont get that steep of a voltage drop across my 4g cable... ill double check tonight with me meter.

But as I mentioned above, I dont see a voltage drop before it combines... my problem is getting it to combine sooner than later.

Could also have been because I was running an 80a isolator. Also changed that to a 200a w/ 200a fuses at the same time, haha. I made a LOT of electrical changes all at the same time and it fixed about every issue I had. At this point I have more than enough flow for anything and everything else that I may want to connect in the future. I even ran 1/0 gauge to a fuse block in the cargo area from my house battery for rear lights, fridge, and accessories to keep the voltage drop down for stuff in the rear. It's all overkill at this point.

 

[sr3tlaw]

Yikes, that sounds really low. I can't remember what I was at before I upgraded to my 240a alt and big 3, but now I sit around 13.6 at idle in park with no load, and 13.6-14.0 at 2.5k rpms depending on charge. I have a dual digital monitor in cab to watch both batteries and those numbers appear to be my averages.

That's actually very helpful information. My girlfriends 2015 RAV4 with 13k miles in drive under the below conditions actually dips to 12.5v:

-A/C full blast, defroster, highbeams, windshield wipers full blast, radio and brake light all applied. (everything that has an on button)

I'm curious if you could test under the same conditions after engine has reached operating temperature, with the batteries isolated?

Would be much appreciated

 

[Drunner97]

That's actually very helpful information. My girlfriends 2015 RAV4 with 13k miles in drive under the below conditions actually dips to 12.5v:

-A/C full blast, defroster, highbeams, windshield wipers full blast, radio and brake light all applied. (everything that has an on button)

I'm curious if you could test under the same conditions after engine has reached operating temperature, with the batteries isolated?

Would be much appreciated

With the 240a alt and big 3 upgrade I'm getting 13.8-14.2 on the starting battery isolated. Before I really wasn't seeing anything higher than 13.6 at 2k rpms I believe. Maybe 13.1 at idle? I don't remember but I can check my Tacoma though on Sunday when I get back home and see what it's running at with the stock 130a alt and stock wiring on my 4.0 engine. Not quite the same because it doesn't have as many electrical nannies as the 4runner does, but it would be a good baseline for the 4.0 and a 130a alt.

 

[riceandpho]

so you dont use a shorter belt with your high output alternator? i know my mechman alternator uses a smaller pulley that required me to use a belt half inch to 1 inch shorter than stock.

 

[Drunner97]

so you dont use a shorter belt with your high output alternator? i know my mechman alternator uses a smaller pulley that required me to use a belt half inch to 1 inch shorter than stock.

Probably I just haven't swapped mine yet. I know I was chatting with another guy in a different thread that provided part #s for a shorter belt.

Sent from my Nexus 6 using Tapatalk

 

[riceandpho]

Probably I just haven't swapped mine yet. I know I was chatting with another guy in a different thread that provided part #s for a shorter belt.

Sent from my Nexus 6 using Tapatalk

i think that was me lol.
5070835 dayco is stock size
5070825 dayco is 1 inch shorter

 

[Drunner97]

i think that was me lol.
5070835 dayco is stock size
5070825 dayco is 1 inch shorter

Hahah. Probably. I lose track of who I'm talking to half the time. I'm pretty active across multiple forums and sometimes the technical threads get crossed since I have the 4.0 in both my runner and my Tacoma.

Sent from my Nexus 6 using Tapatalk

 

[pearlj10]

Does anyone have the correct lengths handy for the - battery to chassis, + battery to starter, and + battery to alternator wires? My - battery to chassis and fender wires are in rough shape so I need to replace. Figured I'd complete the big 3 upgrade while I'm at it.

Thanks

 

[riceandpho]

Does anyone have the correct lengths handy for the - battery to chassis, + battery to starter, and + battery to alternator wires? My - battery to chassis and fender wires are in rough shape so I need to replace. Figured I'd complete the big 3 upgrade while I'm at it.

Thanks

you will always want extra, i say get like 5 for pos, 8 for neg.

 

[YetiX]

Ok, so what is "the big 3 upgrade"?

 

[Bumbo]

Ok, so what is "the big 3 upgrade"?

Its basically a mains wiring upgrade for your trucks electrical...

Generally it consists of upgrading the size of the wire that connects the alternator positive to the battery, negative cable from the battery to the chassis, and the chassis ground to the engine block.

Basically you do this is reduce voltage drop across the system (making it more efficient), and to build up the electrical system so it can actually handler higher amp loads. That includes but not limited to a high output alternator upgrade.

Its a pretty basic upgrade, but it's not always needed depending on what your actual needs are, but it also never hurts to do it.

 

[jpgade13]

2002 4Runner

I want to do the big three upgrade and I understand most of it the only question I have is while tracing my current wiring I see the wire from the alternator goes to my fuse box and then to my positive battery. Is it running through a fuse hear or was that just how they ran power to the fuse box. In all the pics and post I see/read about going straight from the alt to the battery

 

[riceandpho]

I want to do the big three upgrade and I understand most of it the only question I have is while tracing my current wiring I see the wire from the alternator goes to my fuse box and then to my positive battery. Is it running through a fuse hear or was that just how they ran power to the fuse box. In all the pics and post I see/read about going straight from the alt to the battery

its running through a 140amp fuse in the fuse box, when doing big 3, fuse the positive wire , find a 140amp fuse, but most likely to fine 120-125 amp.

 

[Perreyrl]

lol, I feel ya. Maybe someone will chime in and point us to this mystery ground zero.

I have much more pressing electrical problems though. My voltage is all over the place. Even after new 3 new alternators I'm hovering at 13.1v with no load, and 12.7 with hi beams, A/C etc.. on.

I found it by accident. Didn’t see if anyone had posted this or not, but while doing my Doug Thirley headers, the block ground connection is behind the factory manifold cats on the drivers side. Now behind my headers. I am also upgrading all battery cables and will be pulling the intake tomorrow. Just wanted to share in case anyone was still wondering.