# Big 4 upgrade and multiple fuses?



## wayne2008 (Apr 21, 2013)

Hello all,

After about a year of running a Sundown SAZ-2500D V.2 on a stock alternator, I finally decided to bight the bullet and buy a DC 320 max amp alternator. I've been avoiding this because my alt looks like a pain in the ass to install, so i've also avoided the big 3 upgrade. Through my research I came across a few threads talking about running a cable from the back of the alternator/negative post to the negative battery terminal. Has anyone heard of this or done this, and is it worth it or does it have any potential drawbacks? 

My other question is about fuses. In one tutorial video of hooking two batteries together he talks about using several fuses, so I would like to know if these are nessicary or not. I have spent some time diagraming my new wiring, please take a look and let me know if this looks right. I appreciate any input, thanks!

http://imgbox.com/3gwzjlwX


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## mikey7182 (Jan 16, 2008)

Your system diagram looks perfect, except I've not seen an alternator that has a negative post on the back. They are typically grounded through the plug/harness, and only have one stud coming off the back (Brokeback joke?  ) which is 12V+. So you'll want to run upgraded wire from the alternator post to the (+) terminal on the main battery. The factory one typically isn't fused (at least in the cars I've owned) but if you want to fuse it near the battery that should be fine. I wouldn't bother with a second fuse near the alternator, depending on the length and AWG of your wire, but then again, more fuses is not necessarily a bad thing either.

As for the Big 3/4 upgrade, typically, one is battery (+) to alternator (+); then battery (-) to chassis/frame; then chassis/frame to engine ground (either find the factory one or find a bolt that is easily accessible that goes into the motor). 

Also, I usually fuse at the distribution block (anywhere you are dropping wire size) but I see you have fuses near the amp on the (+) side so you should be fine there.


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## wayne2008 (Apr 21, 2013)

mikey7182 said:


> Your system diagram looks perfect, except I've not seen an alternator that has a negative post on the back. They are typically grounded through the plug/harness, and only have one stud coming off the back (Brokeback joke?  ) which is 12V+. So you'll want to run upgraded wire from the alternator post to the (+) terminal on the main battery. The factory one typically isn't fused (at least in the cars I've owned) but if you want to fuse it near the battery that should be fine. I wouldn't bother with a second fuse near the alternator, depending on the length and AWG of your wire, but then again, more fuses is not necessarily a bad thing either.
> 
> As for the Big 3/4 upgrade, typically, one is battery (+) to alternator (+); then battery (-) to chassis/frame; then chassis/frame to engine ground (either find the factory one or find a bolt that is easily accessible that goes into the motor).
> 
> Also, I usually fuse at the distribution block (anywhere you are dropping wire size) but I see you have fuses near the amp on the (+) side so you should be fine there.



Thanks for your reply! It seems that I should ground the engine block to chassis rather than battery to engine block? I think it would all work the same, but possible more efficient the way you stated? This is the video that got me pondering on the extra cable from (-) alternator to battery (-) . Maybe this dosnt apply to most alts but its interesting if you'd like to watch it, only a few mins long.

https://www.youtube.com/watch?v=K3EFGlHPFDk


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## Beckerson1 (Jul 3, 2012)

The standred big grounds at the engine block which then is grounded to the alt. Running a dedicated alt ground to battery tends to eliminate a lot of resistance as your not trying to run electrons through the block to alt and vis virsa. Supposed to provide a much better ground connection to the alt. 



Just do what you have pictured (might be overkill but hey your covering your bases).

As far as multiple fuses. Unless all your batteries are next to each other you should fuse for long power wire runs. As long as you use quality fuses/fuse holders and make sure connections are solid you shouldn't have a problem. 


Looking at the pic it would save you one less fuse if you go with a fused distro block for the power from amp battery to amps. 

Other then that it all looks good. Nice and safe.

8m assuming battery up front and battery (ies) in the rear. If not I can see needing that extra fuse btw.


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## wayne2008 (Apr 21, 2013)

Beckerson1 said:


> The standred big grounds at the engine block which then is grounded to the alt. Running a dedicated alt ground to battery tends to eliminate a lot of resistance as your not trying to run electrons through the block to alt and vis virsa. Supposed to provide a much better ground connection to the alt.
> 
> 
> 
> ...


Thank you, yeah the first battery is engine battery and second one pictured will be next to my amplifiers. Do you recommend any specific brand of ANL fuse/fuse holder? I dont mind paying a little bit since this is an important link. I'm not sure if i can trust amazons ratings on this item and i want to make sure i get something quality. For cabling i'm also going with KnuKonceptz KCA Kandy Kable CCA 0 Gauge, from what i've researched this is one of the better brands. I'd like to get the 4/0 cable but its quite expensive.


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## mikey7182 (Jan 16, 2008)

You can always do two runs of 1/0 if you feel the need. 

Where are you guys seeing a ground on the back of alternators? Have my vehicles just been weird? I've done several Big 3 upgrades and never seen a negative terminal on the back of an alt. Or are you just talking about grounding at the mounting bolt where the alternator bolts to the motor?


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## wayne2008 (Apr 21, 2013)

mikey7182 said:


> You can always do two runs of 1/0 if you feel the need.
> 
> Where are you guys seeing a ground on the back of alternators? Have my vehicles just been weird? I've done several Big 3 upgrades and never seen a negative terminal on the back of an alt. Or are you just talking about grounding at the mounting bolt where the alternator bolts to the motor?


Yeah I think they're running it from the mounting bolt


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## Beckerson1 (Jul 3, 2012)

mikey7182 said:


> You can always do two runs of 1/0 if you feel the need.
> 
> Where are you guys seeing a ground on the back of alternators? Have my vehicles just been weird? I've done several Big 3 upgrades and never seen a negative terminal on the back of an alt. Or are you just talking about grounding at the mounting bolt where the alternator bolts to the motor?


There isn't a dedicated ground point on the alt. The alts chassis is the ground. That's why you have a chassis to engine block ground.


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## bkjay (Jul 7, 2009)

One thing to keep in mind. If you blow the fuse on battery feed going to the alt. The alt. side of the wire is still going to be hot when you car is running. So a fuse at the alt. is not a bad idea.


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## invictuz (Jul 16, 2012)

Quick example of one manufacturers fuse recommendations for dual battery configurations:


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## Sine Swept (Sep 3, 2010)

I would also suggest not grounding your amps at the battery negative post. If you were to somehow loose a ground from battery to chassis, it is possible to then have your amp become your circuit to ground. Connect your dedicated amp ground to the same point your battery to chassis is grounded. This way when your negative is taken off of the battery there will be no path from the battery to the dedicated amp wiring. 

I will also agree with a fuse between alternator and battery. I run 1/0 pos and neg to distroblock's in the rear and have never had any issues, even with my Optima Yellow that is from 2005!!!


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