Hi forum team'

Whenever I decide to post some 4Runner modification or build project that I'm involved with, before I post it, I'll always ask myself if this will add anything to the forum that's different from what has already been contributed, or is it just... da' same ole thang'. But I really like when I find out that it's different because I can't find much info by doing a search, and that's sorta what happened with this. Before my new alternator arrived, I did a 5'th gen 4r alternator replacement search; guess I felt a little 'intimidated' due to the lack of room available in which to remove the old one. But during my search, all that came up were ad's for "Auto Zone, Amazon, Pep-boys, ebay"...etc so I decided to write something about this myself! I also thought that this subject, while not particularly innovative or taboo, may not be as common or as well understood as some other subjects, so there may be a place under the heading of 5'th gen 4r alternator upgrading! Allow me to offer just a little background to the chain of events.

I bought my 2012 4Runner L.E. back in April of 2012. Since that time, I've added a few amenities e.g., PIAA fog light (520) kit, "Dual (750w rms) power amplifier" Sub-woofer system, software driven PEQ and x-overs... yada, yada, yada! So I decided that I needed to upgrade the vehical's stock 130 amp electrical system to prevent having a constant current overload on the truck's main electrical block and, to meet the increased electrical demand imposed by the installed, and future, "after market accessories".

Our O.E. Toyota alternator (small case "Denso hairpin") will deliver about 130 amps @ full output (appx 80 amps @ curbside idle); "for a luxury vehical, that's barely enough for it's standard electrical components". Just a few months ago, I discovered a company by the name of "DC Power engineering", who claimed to build a large case "Denso hairpin" alternator capable of 270 amps full output (180 amps curbside idle).

Well, this alternator (270XP), will fit in the exact same footprint as the original, even the wiring harness will align w/ no mods so I ordered it but It'll take up to five weeks to arrive because it's "made to order", said the C/S gentleman. Looking at the original one and trying to assess the swap, there's really not a lot of room to remove it from it's operational location. I did quite a few searches trying to find someone (anyone), who has done this before but I came up "empty handed".

I know it's not a big deal to swap an alternator; at least most of them aren't. I was an auto mechanic in the old days; mid 70's to mid 80's. But after that I went into the Commercial-Indus'l Air conditioning/Building controls field, joined the 'Steamfitters union' and have never looked back! But now, some twenty plus years later, I barely remember how to open the hood...... If it's something that I can do in my driveway then ok, I'll do it. But, if I'm going to get half way into the job then learn that the power steering lines or freakin water pump has to be removed first, I'm gonna be... !!! hahahaha!

I don't know if anyone else here has ever changed a 5th gen 4R alternator yet, but if you're planning it or need to... BEWARE! Looking at it, standing in front of the truck, you can see that it might be a b*tch getting it out from it's station. The engine head overlaps it on top, the a/c compressor beneath, hoses/piping and large harness to the right, and engine block to the south,ugh... There are, what looks like two bolts (through the 'ears') holding it in place. But what you can't see is a third bolt and bracket down underneath the alternator, securing it to the exhaust manifold which is very difficult to remove from up top; glad I had my mechanic taking care of it for me this time (my mechanic >< me)... dodged a bullet! Additionally, there is an electrical system harness that's secured to the alternator as well, so IF you ever need to R&R your alternator on a 5th gen, give yourself plenty of extra time to do this one; even the service time estimate guide advises 1.5 hrs to do this job, which is just short of the actual time that it took and this mechanic works really fast.

Snapped a couple pics.

BEFORE


AFTER

Perty ain't it!!

Back in January, I took a couple of pictures of my volt meter read-outs (O.E.M. alternator) under very different conditions. The first is just after starting the truck. There were no lights on in the vehical (during the day), and I deliberately shut down the heat (blower fan), and the audio system. Here's a snap-shot of an "UN-LOADED" charging system voltage reading (taken @ idle); cold battery (ambient temp=18 deg F), "standing voltage" was @11.49 (w/engine off).


As you can see, the battery/charging system voltage is good (still 18 deg F) @12.83, as indicated by the "battery icon" (showing full) on the right of the numeric display, and the green 'LED' just beneath the number 12. The alternator is trying to replace the battery's surface charge, depleted by start-up and the severe cold; it will eventually rise to 13.9 volts before leveling off at 13.8. Incidently, the two JL Audio "HD-750/1" power amps will consume about 56 amps (each), to deliver their full output of 750 watts true rms . So that's 112 amps from a gross budget of 130A, leaving only 18 amps from the "full-fielded" alternator. Then, there's another 'add-on'. The PIAA 520 foglights, which can use up to 10 amps gross, leaving only around eight amps to run the truck... and to charge the battery! Here's another snap-shot of a completely loaded charging system voltage reading (taken @ idle) at night. The engine has reached it's normal operating temperature, and the low beams, foglights, heater fan and the audio subwoofer system, are in full operation at this time.


As indicated by the voltage monitor in this photograph, the battery icon is "completely depleted", and the red 'LED' is showing an urgent warning, prompting the driver to get this checked ASAP!. Now, I'm not in the habit of abusing my truck, it's audio components, or it's electrical system; this 'overload' condition was created just for this test. But if I wanted to operate it's electrical loads at full potential, I'd like knowing that it would be just fine!

"CONTINUED BELOW"

"CONTINUED FROM ABOVE"

After the new alternator was installed, a second test was implemented: "Here are those results"

In the photo down below, the battery is partially discharged due to having been disconnected and then reconnected, and the engine started several times in the shop. The electrical system is completely drained of any stored voltage (used for clock memory, radio pre-sets, ecm data storage, etc... ), "The monitor represents a partially drained battery w/icon reading about 50%; engine off."


Okay now to start the engine, see monitor below:



I have my electrical monitor plugged in as I did before, but this time the numbers are very different. This image shows an "UN-LOADED" charging system, no radio, no wipers, no heat or a/c operating at this time. The new alternator has just been installed. As indicated by the battery icon above (just to the right of the numeric value), it shows that this battery is depleted of any 'deep charge', only a surface charge is indicated (see the "12.19" in the previous monitor photo; amber warning indicator on).

After driving home from the repair shop, about a 20 min drive, you can see that the battery's "state of charge" has improved greatly, as indicated by the battery icon below. After just pulling in and sitting still in my driveway, I'm "loading" the charging system up as before; wipers on, subwoofer system, headlights, fogs, a/c system on etc... but you see a very different reading as compared to the results that I documented in my last post of 12.83v, w/ 'LED' showing an urgent warning, for me to have this condition checked asap.



This time, an ideal reading of 14.12v is shown (everything on); no red LED warning light or high pitched whine of an overloaded, full-fielded alternator that can't keep up. Just a healthy electrical system that has plenty of power to spare 'if needed'.

Now, I'll still need to upgrade the factory battery/charging system cables in the 4R due to the increased capacity of it's electrical system. Rather than ripping out all of the original factory cables from their tightly routed locations, I've decided to allow them to continue operating exactly as they have been but used a 'partner' or 'tandem' (parallel) cable configuration instead. By doing this, you will increase the Load carrying capacity of those specific cables of concern, by adding an additional electrical path for current to flow through, so they will 'share the load'. I picked up some new brass battery terminals from Auto Zone, along w/four, 4ga x 19 inch cables with "looped" ends, for 'Quick Connecting' with lugged terminals.

I also looked for a 140 amp ANL wafer fuse (to match the original factory circuit), w/fuse holder but couldn't find one so I went online and ordered some from amazon, along with a 100' roll of 3/8' "split loom flexible conduit" for that professional touch. Once the order arrived, I began putting my components together for installation the next day.

Here's a sketch of the wiring build-up to give an idea of exactly what's been done:

The dotted lines represent the existing factory cables, which I've left in place. The solid lines illustrate the new, heavier 4ga cables that were installed; I think the factory cables are 8ga, kinda small.

Here's a couple of pics I snapped of the finished product below; really not much to see but...


Forgot to show the "before/after" views but just go outside under your hood and look... hahaha!




Here (above) is a look at the new "Brass" negative battery term, new cable, and fender "ground" terminating points (original factory ground cables just above relay/fuse box, and "added cables", over on the (far) extreme left fender panel)

A little better view of the same cables as above (neg battery and engine cables to body ground):


Now below, the new "engine to body" ground cable. This cable terminates at the same spot on the fender as does the new neg battery cable (pictured above)


It was very difficult to show this new "Main pos (+) power cable", which extends from the alternator (B term) output lug to the (Hot) battery terminal; via the 140A auxiliary fuse.


NOTE: This fuse was added to be in compliance with Toyota's electrical system wiring safety provision. The idea is that in the event of a serious front end collision, should the main battery cable be severed from the alternator, it's 140 amp main fuse would offer an opportunity to "disconnect the power", to prevent an explosion or fire.

Located on the leftside wheel well, this 140A ANL wafer fuse joins the new auxiliary Generator output cable, and new 'Positive' battery supply cable.

This project has been very fulfilling for me. No more low voltage output readings when accessories are being used. No more dimming or oscillating head lights when music is pumped up a bit, and no concerns as to what the vehical's electrical system can and cannot do. I'll be posting again if anything changes! hope someone else can use some part of it to benefit in some way as well. Happy trails!

rigtec

Very cool @rigtec . Strong work. I think anyone who runs a heavily upgraded stereo system, or tons of aux lights (that aren't LEDs) should think about following your foot steps.
Very nicely done, and good write up.

Question:
(premature apology for newbie electrician question) Is there a chance that the upgraded alternator, that is now kicking out more power, over powers and burns anything up? Or is the alternator just charging the battery stronger and faster?

Cheers

Holy... dude. Your wisdom on electrical is amazing. When I was in high school auto shop class, I kinda dropped off the map when we got to electrical systems and ended up leaving the course. Wish I woulda stuck with it. I'm kind of following what you're saying, but the wire guide and all that throws me. I just need someone to explain it barney style for me I suppose.

The take away though, from what I understand, is that the factory alternator is just sufficient enough to run the 4Runner without any additional electrical components. If you add anything; lights, fridge, upgraded stereo, new switches, etc then you should upgrade the alternator, battery, and cables. Correct in my understanding?

Very nice writeup Rig. With just basic electrical knowledge, I understood everything you wrote.

With all the members that have added electrical goodies, I suspect several will follow suit.

Someone is bound to ask about your monitoring device ....

EDIT: *device*

what monitoring device do you use?

Very nice job @rigtec . I've looked into the alternator aspect of our truck as well and my first project was related to the cables (to make them longer so they would work nicer with a Group 31M battery).

Details on that adventure can be found here: Okki's Build Thread

The pictures etc may also help anyone else venturing down this road. Looking forward to hearing a long term report on how the new alternator is holding up.

Okki

Hi MadeInMaine'

No apology necessary, and thank you for your kind remarks! I am sooo glad you asked this question, perhaps now we can begin to dispel any myths... floating around that are built upon a lack of understanding! You'd be surprised how many people (educated folks) believe that if you installed an alternator with more capacity than needed, that the vehical would start to blow fuses or burn-out it's electrical components. Think of it this way: Would replacing a 525 CCA battery, with an 870 CCA 'Die-Hard' have an adverse affect on the vehicle's electrical system? Here' another one: Will adding $10,000 bucks to a $50 dollar bank acct 'force' the acct holder to spend more than their budget? (well it might, but that's a discipline issue, bad example! lol).

Okay, just one more (this is fun ): Most average residential homes have a 100 to 250 ampere electrical panel in it's garage or basement. The utility 'electric and gas company' has an electrical grid at the home's service hook-up (the meter), which can provide more than 10,000 amperes to that entire block on demand if needed; remember, this almost limitless grid is already hooked-up to the home! See my point? Just having an available electrical resource like a "Dual battery set-up" or a "Triple High output alternator bundle" is only a pool which can only make electricity available when needed and cannot cause the vehicle to consume more current than it needs. "The electrical system puts a demand on the generator; not the other way around!" Hope this helps,

best regards!

This is a very informative, intelligent, and well thought out process. You obviously have some extensive electrical knowledge. I appreciate the effort it took for you to plan this out and execute it extremely well.

So, since I can't necessarily compete in a electrical quiz battle with you. I wanted to tell you that it's "vehicle" not "vehical".

Excellent post! Thanks for sharing!

Good job! I have "chased" alternator, heavier wiring and battery capacity in previous VEHICLES (lol) and its better to just upgrade everything at once and be done with it. An electrical engineer once gave me some words of wisdom that are worth repeating here and may help some of you new guys: "Your supply can be greater than your demand but if your demand is greater than your supply there's going to be trouble in circuitville."

Hi 1Eng'r

Thanks so much for your generosity and kind words, they are much appreciated! Your electrical engineer colleague would appear to be 'wise on an epic scale'; I've never heard any theoretical principle, phrased so eloquently; very much poetic!

Greg (rig)

Hi philsey,

I sure hope so, gotta protect the 4Runner!

My "on the fly" charging system monitor is made by 'Innova'! Plugs into the cigarette lighter, features an "old eyeball" friendly screen, and is accurate down to a 100'th of a volt (not a tenth... one hundredth')! Cost, $13 bucks. Gets great reviews, Here's a link: Amazon.com: INNOVA 3721 Battery and Charging System Monitor: Automotive

Thanks for your reply! rig

The only thing I would suggest is you load the system and take ammeter readings of the factory power wire and the new power wire you've installed to make sure you are not overloading either. Paralleling cables of different size and length can cause issues. Electricity is stupid and doesn't go "hey look at this big new cable lets go down this one instead of that smaller one".

Hi VoodooTitan'

You are very correct in your understanding! You should give yourself a bit more credit because you just threw exactly what I said in the thread straight back at me! I don't think the 5 gen is ill equipped in the least. But... if the fuse sizes are any indication of what the truck is actually capable of consuming e.g., high velocity blower (50A), wipers (10A), headlights (10A per bulb or x4 or 40A), de-icer (20A), heated mirrors (10A), etc... That's 130A right there. (I was quoting these fuse sizes from my "Mitchell auto electrical service guide" where the fuse sizes are posted for 2011 4Runner).

Okay, but that's 'worst case scenario'. So let's say that the accessories are valued at 80% of the total fuse rating, meaning that if a fuse is rated for 10 amps then the device it protects will be consuming 8 amps full load. So that means that the 130 amp estimate that I just gave is over estimated by 20%. So 110 amps (total system load) plus 20% (safety factor) =132 amps. That sounds about right! We might have just enough juice to handle the truck's full load "everything on" at the same time; but we will probably never actually do that, not likely. This is the very first time that I sat down to calculate the truck's potential load. But that's about it; remember, I never did factor in the engine's operating budget (current), so there's nothing left over.

That's why it is a very good idea to beef up the 4R power plant and grid! Thanks for your thoughtful reply VoodooTitan! PS: If you ever want to go over some of this stuff, schematics, wiring, electrical projects, or you just need a diagram, shoot me a PM; I'll be happy to jump in!

rig