Alternator Swap - 180A Highlander and 270A DCPE

I have a 2022 TRD Off-Road DCSB that I've been interested in swapping the alternator on recently. My truck is heavily modified from stock to serve as my home. I live and work out of the Go Fast Camper on the back. I've removed both front and read passenger seats, and replaced them with a deck to sleep on in "stealth mode" - and underneath are 200Ah @ 12V of Battle Born self-heated batteries wired 1S2P. I have 400W of solar on the roof of the GFC, but during winter it's hit or miss if I can charge much from the solar array. I started out with one Victron 30A DCDC converter, but found that I needed to idle my engine when at camp to support my electrical needs. I typically have a fridge, propex heater, starlink, laptop, phone, and radios to power.

I added a second Victron 30A charger, but 60A was too much for the alternator to provide at idle. I had the 130A alternator stock from the factory, and the truck has 25k miles on it. I found that if I revved the engine to about 1000 RPM, the alternator could supply the required current without problems (as I would expect). Below that, the alternator couldn't keep up and the voltage nose-dived.

After a few weeks of searching, I stumbled across another thread here where a member had suggested that the 2GR-FKS is also used on the Sienna and Highlander, which have a 180A alternator. I considered the high-current aftermarket alternators, but decided against them because I'd much rather have an OEM part that I can trust the quality and longevity of.

I couldn't find any evidence of anyone ever finishing the swap online, so I ordered a $125 eBay alternator from a scrapped 2017 Highlander (27060-0P420). I wanted to test if the concept could even work before springing $400 on a new OEM version.

Today I spent the better part of 12 hours taking the old alternator out and putting the new one in. It would have gone much faster if I had looked at the TIS manuals earlier and ignored the bad advice on the internet about how to change the 3G alternator. There's not a lot of info, and the little info there is has errors.

Here's new (front) and old (back) alternators. Case size is different, but mounting holes match up.



Note that the "hidden" bolt in the back is not the one that bolts straight into the alternator, as some others suggest in their tutorials. You are much better off removing the one on the bracket that connects between the alternator and the engine, on the engine side. Still a PITA but somewhat doable.

The connector locations are different. The lug size is also different. Rather than modding the factory harness, I crimped up a piece of 4AWG wire with a 6mm lug on one end and an 8mm lug on the other. Bolted together with M6 locknut and screw and covered with electrical tape.



Next photo - the bracket on the back of the alternator. You need to remove the wire harness from the top hole, and the bolt from the one underneath. This is shot from the wheel well with my phone, but you'll need to reach in from the top to undo the bolt. Putting it back together is a mess, it took me a bunch of times to get the holes all aligned because you can't see anything when you're doing it. It's all by feel.



The LIN connector is the same but positioned differently, you'll need to install the LIN cable before putting the alternator into its final position because there isn't enough room to plug it after the alternator is bolted in.

Results

I buttoned it up and drove around the neighborhood tonight, it seemed fine so I drove it at interstate speeds for 2 hours. It seems to have worked just fine. No error codes. Voltages seemed right for charging the battery.

The disappointing thing is this - it seems like the Tacoma's idle speed is still too low to make this thing produce 60-70A for the chargers. I made a temporary change to the engine shutoff detection settings on the chargers that makes one of them on all the time, and the other turn on when the voltage is high enough. If the engine is above 800 rpm, they are both on with no extra voltage droop beyond resistive drop on the wire. I was charging at 60A all the way to camp tonight.

I removed the factory inverter for the 120V outlet, so at 400W savings on that I figure there's enough spare in the power budget for 720W of charger. I need to re-visit fusing of the system, but that gave me enough confidence that I could get away with this without blowing the 140A fuse for the battery.

Next steps

I'm happy with the extra overhead this gives for power, but I need to do one of two things to make this work at idle (or both):

1. Increase the speed of the alternator either by using a smaller pulley (current pulley is 55mm or so) or by tuning the truck to idle higher.
2. Sense when RPM < 900 and shut off the second charger so I'm only charging at 30A, which the alternator can handle just fine.

I'd love some feedback from people familiar with VFTune or other options. Could VFTune bump my idle to 800 or 900 RPM? I'm almost always at 550 or 600 when idling. I doubt I can get a smaller pulley that will bump the RPM by 50% - it's a small pulley as it stands.

Thoughts?

If I end up going with this, I'm going to replace with a new OEM alternator. I'll take more pics if that happens.

 

A tuner can set your target idle to anything you want.

 

Any suggestions on which tunes to consider?

 

Update on this -

About 500 miles later and still going strong. Will probably keep a spare alternator on hand but keep this one running until it starts hesitating

Yesterday I got the Overland Torque Tune (OTT) done in SLC. Thanks Barrett!!! We swapped in an AGM battery and he bumped the voltage on the alternator for me so it charges all the way up to 100%

We also bumped the idle speed to 750rpm. There's a bug in the tuning software that prevented them from making the high idle work in park and neutral, but it works when the truck is in gear. I wired my two Victron DC-DC converters (Orion Tr Non-Isolated 30A 12/12) to make one turn off in park and the other in neutral. The truck can handle 30A at 60rpm, but needs 750rpm to handle 60A off the alternator. I disconnected the shift position indicator and wired the P and N wires to the remote switch on the chargers on the "L" side. This is a temporary fix until they fix the bug in their software and the idle goes to 750rpm across the board.



I moved the 4AWG wire going to my DCDC in the cab from the battery terminal to the alternator directly, through a fuse.

I think this works. Happy to answer any questions people have. The 130A alternator may probably be able to handle some loads, but I like the peace of mind of having the extra overhead and not running the alternator at full tilt all the time.

 

I have always been planning one of these:

https://www.dcpowerinc.com/products/270-amp-xp-high-output-alternator-toyota-tacoma-3-5-2gr-fks-v6

but I can understand why people would prefer OEM parts. It just seems like this is one aspect where a quality aftermarket product would outperform one meant for the masses with cost considerations.

 

Did I read that correctly? It shows 198 amps @ idle? I would expect them to offer a harness upgrade with that but it’s easy enough to make one.

 

That’s what I read as well. Not cheap but if you like overkill, that plus a fuse and a big 3 upgrade would have you pumping the juice. SDHQ sells this model and might offer an install kit.

 

FYI for your high idle situation......
I had a GMC 3500 (gas V8) that came with a universal high idle kit (in my case, to bump up engine speed for a hydraulic PTO pump) It was just a little box that mounted above the gas pedal and had a threaded and adjustable, plunger-style rod that popped out and pushed the gas pedal when a toggle switch was flipped. It was so simple and great because it could be adjusted from stock idle to 1000rpm+ and could be turned off with the switch so it wouldn’t affect the transmission at all...

 

If you look at the back of that unit, I'm guessing they are rebuilding the 180A alternator that I used, and replacing the front of it with a shiny billet aluminum piece. The position of the lug and connector are exactly the same and the size appears to be the same as well. But for the price, I'll happily take the highlander alternator any day of the week.

 

Looks like I need to eat my words.

I decided that the idle output was too low for my power requirements in the camper, so I ordered:

- a DC Power Engineering alternator
- 2 more Victron 30A DC-DC chargers (total count is now 4)
- 2 more Battle Born Self Heated LiFePo4 packs - 12V 100Ah each
- Wire to beef up all the connections
- 150A Mega fuses plus holder - need to run directly from the alternator lug since this much current would blow the Taco fuse. I will need to use the remote control connector to make the chargers turn on only when the engine is on - pulling current out of the battery at that rate will also blow fuses.

Now I'll have 180A idle output, and use 120A and change for the chargers. With the RPM boost I'll never be wanting for power in drive. Having 400Ah @ 12V of batteries will let me run everything I want - 3D printer, laptop, monitor, starlink, propane heater, interior lights, etc. without ever having to think about it. Solar has taken a back seat because it's winter and the panels are hardly making anything.

I'll make sure to document the swap more thoroughly this time.

 

I think it’ll be killer. I’d love to do the same. I’m short on time and lacking real need since my truck is used to take kids to sporting events once a week and sits around collecting dust the rest of the time.

 

I feel you. When I was full timing in my Taco + XOC I had my ICECO 65L dual zone set to a conservative 32 deg F, ran my Pepwave max transit (later my Starlink) and my Dell work laptop off of a Xantrax true sine 1000W and my trailer's dual lead acid 27F deep cycle house batteries would last 11 or 12 hours (maybe) if my 120 W solar array was charging. Three days of clouds in the fall had me idling the Taco on and off all day so I decided to get a little Generac 2000W gas generator. I'm glad I did, that thing is the little generator that could for over 1/2 the price of the Honda that most buy.

Thank you for taking the time to write this up and include pictures (followed thread). I no longer full time in the taco + trailer but I may do some extended trips when spring comes around.

 

Not so fast, the OP is idling at 550-600, mine idles at 600 most of the time. The DC Power website specification idle speed is 750. They take the engine idle speed times three and that gives the Alternator RPM speed and thus the 198 Amps; at 600 engine RPM it only puts out 157 Amps. This is covered in the DC Power FAQs at the bottom of the page.

I will be getting into contact with DC Power soon. Interested.

 

You should upgrade all your stock wiring and get the alternator output directly to the positive battery lug or a positive distribution bus and out of the OEM fuse box. If that is what you mean by your last bullet then ignore what I said

 

@steezeman any chance of you posting a simple diagram of your connections and components? Also, where are the four batteries setting? Interesting about what you are doing here. Back in the late 80's I used a battery isolator in a Chevy Van. The second battery powered the stereo and amps.

 

Oh wow, and I thought I had it bad!

My wife and I live in our Alu-Cab on the back of our DCLB. We run two laptops, two extra monitors, Starlink, a cell antenna/router, fridge, electric blanket (at night, if cold enough, lately it has been), and other small devices off of our setup for our 40 hours of work each week.

Our setup is (2) 100ah Renogy LifePO4 batteries, with 400w solar on the roof. Renogy 50A DC-DC Charger with MPPT. This does everything we need, and I have yet to see our battery levels fall below 50% each at any time. We always park facing due south and I start grabbing amps as early as 15 minutes before sunrise. Do you park facing due south during your work week?

Is your Starlink modified for DC power?

I took the plunge and bought a handful of boost/buck converters, so everything in our truck runs straight off of DC power (meaning no dc-ac-dc switching going on), except for my laptop, which doesn't like not having its own proprietary charger. Maybe look into this?

In my case, my batteries can only be charged at 50A max. That limit exists with them wired in parallel as well (I could be mistaken on this). I don't know if Battleborn has the same limitations, but I would check that before I wired in (4!) DC-DC chargers.

When we had just 200w solar and (1) 100ah battery I did have to idle the truck during two cloudy weeks. 1 hour of idling either every day, or every two days, was all that I needed to maintain a charge level that wasn't detrimental to the battery (80% DoD). Our trucks use approximately .3 gallons of gas per hour at idle, fyi. The truck also shuts off automatically after one hour, so you don't have to remember to turn it off.

 

Yes, will get to it later this week

I was running the renege batteries and chargers for a while, They are a decent system, but the Victron + Battle Born system is way better. I'm especially a fan of how all the Victron BT and serial protocols are open-source so I can add them to my monitoring dashboard that I'm working on. Not a cheap system, but that's not the point for me.

I have parts on order to modify starlink for DC using 12->48V. Already flat-mounted the dish. Will be using a router that can run from 12V. I was in line for the Boondocker.io dishy dualie, but got impatient so I'll just be using the Yaosheng injector.

The only inverter I have at the moment is a 250W Victron model, it's nice because it allows me to charge my Milwaukee batteries. Will be getting a 12V charger for those eventually. Until starlink is on the DCDC converter, it is running from that inverter.

Yeah, the idling has been a fact of life for the last month because it's wet and snowy half the time here in Utah. Will really like having the higher output alternator to minimize or completely eliminate that time.

Just finished mounting my 27" monitor in a pelican case, super stoked on how it came out.

 

With 4 batteries in parallel, I could do up to 200A charging. 4x 30A chargers plus a 35A solar MPPT charger puts me at 155A.

 

Nice monitor setup.

In what ways is that system way better? Is it purely on the ability to monitor what is going on with the system? I am currently content with my setup but always interested in hearing from other people using things as I use them.

How do you reconcile having the dish flat mounted (I am assuming on top of your tent) with the fact that the solar panels need to face south, while the dish needs to face north?

I feel you on Utah. Was just there for a few weeks, and it was cold and cloudy!

GM - 11-23 - 1 by Michael Rickerd, on Flickr

 

Other than the monitoring (I'm an engineer so I care about silly things like that) - more durable, seems like it is more predictable, and the BB heated LiFePo4 packs have a heater enable lug that makes it possible to turn the heater on when there is no external input. The Renogy batteries need a charge going into them to preheat the batteries before they start charging below 32F. I have two friends with the DCDC 50A plus MPPT from Renogy - when they have any solar input, alternator gets cut to 25A of charging.

I mounted the dish on my Prinsu habitat rack. Tbh, I think there's enough satellites in the sky now that it really doesn't matter which direction it is facing. I drive with it on, and even though I don't have the in-motion plan it still works really well. You can see the dish on the passenger side here. I take video calls on this every day without problems. Only thing I need to fix is shimming the back side so the snow melt feature doesn't create a puddle of water on top that blocks the signal