DIY Electric Car Forums banner
1 - 19 of 19 Posts

·
Registered
Joined
·
9 Posts
Discussion Starter · #1 ·
Hello all,

I've been a long time lurker of this site and hopefully in the next few months I'll be ready to pull the trigger on starting this project and have wanted to build an electric car since I was in high school 8 years ago.

It's a 2000 Ford Excursion with 4x4 drivetrain. I already have a Tesla, and I'm fond of the idea of having a full size electric truck. The feasibility of my goals is largely based off of what Ford has done with the F-150 lightning.

I'm looking for recommendations/back board ideas on what motors/batteries/etc I should get for this. Current plant equipment is:
Tesla LDU or any motor honestly that's capable of producing 150 KW
Any wrecked EV(s) with matched battery packs that will get me to 85 kWh worth of energy.
As far as gearing, I will likely use the transfer case in 4Lo with the front hubs unlocked unless needed. The final drive ratio will be about 11.1:1

These are the goals for the vehicle:
200 miles range (realistically will accept 150-180 miles) if using 85 kwh worth of batteries. If I can fit more cells in I will.
80 mph top speed but the handling characteristics of this truck will never have me exceed 70 mph.

Ideally I would also like to have DCFC capability, but if the ability to have that is considerably difficult what would it take to make this a series style hybrid.
 

·
Registered
Joined
·
3,559 Posts
Impossible.

7200 lbs of pig, as curb weight before you load it up with battery, pushing huge amounts of air down the interstate at 70MPH as a giant aerodynamic shoebox.

85kWh will likely get you 100 miles of highway range -- at nominal speeds (55). At 70MPH, I'd bet it'd run maybe an hour on a 85kWh pack before draining it completely. Guesstimates.

Tesla LDU/motor will likely die pretty quickly under the loading, imo. Tesla Tesla Tesla. They are garbage under high continuous loading. It's spec'd to do occasional 5 second dashes to impress your nerd accounting dept colleague, not push a diesel truck down the road at 70MPH all day.

Of course, you'll want to tow a trailer with it that you didn't mention...

4 wheel low may work with the math, but there's no way your transfer case will live through continuous 11,000 (swag) RPM input. And the gear noise/slop/imbalance will drive you nuts.

DCFC requires a lot of skill to integrate and you have to ask why it's needed because with 100 miles of range; it's a local vehicle unless you double or triple up on the battery. Then, at a quarter megawatt hour, you can't get enough charge into it fast enough unless you do some really heavy lifting on the system thermal design.

Hybrid? Buy another truck (or do a total transplant from one) that's a hybrid because there are few people on here with the ability to write the s/w to do a hybrid and interwork it with a reverse-engineered ICE system and just about as many people who would not touch doing a hybrid for the time/risk/benefit(zero) of doing one.

It's almost as interesting as my F-450 that's in the queue. It will need at least three Teslas' worth of battery and the stock market to fund it sucks right now. 85kWh...I could only wish. Everything on a 4-5 ton + truck/bus gets "interesting", but it's far from being as straight forward as doing a car. And it's an 80 to 100 grand project on a good day (did I mention the stock market sucks these days?). How many gallons of biodiesel is that?

No, I doubt that you can turn one Model S's guts into an Excursion that's worth the effort of doing it, especially with the fantasy performance targets you've spec'd.

Three cars', maybe two, worth of donor...not one. For the battery. Then a truck-duty electric motor that starts at $25 grand.

You are always free to go for it and show us what can be done vs my Negative Nelly analysis here. I just don't see a Tesla motor or 85kWh working in a 7200lb curb weight aerodynamic brick.
 

·
Registered
Joined
·
9 Posts
Discussion Starter · #3 ·
Most of my optimism for why I think at least 140-150 miles is possible based off of the Hummer EV. That thing is by far the least aerodynamic and least efficient EV on the market making it a great bench mark for EV SUV conversions. It's rated at 329 miles using a 210 kWh pack while weighing 9000 lbs, running 35 inch tires, and more possibly the most lifted truck on the market. I'm planning on staying stock with 31 inch tires. I'm confident with 85 kWh (Okay maybe 100 kWh) I can crack 150 miles.

With the gearing of the T-case and my rear end, the motor will be spinning about 8500 rpm. No lie this is a concern but if I'm going down this rabbit hole I'm gonna prepare to have to rebuild the T-case and figure out a way to get an aftermarket UD unit to increase the gearing.

Towing a trailer is a non concern for me. Any trailer I tow is short trips only no more than 50 miles round trip.

As far as weight goes, after ripping out the engine (700 lbs), transmission (200 lbs), gas tank and fuel system for the 44 gallon gas tank..... (300 lbs), Installing 85 KWh would be about 1200 lbs plus 300-400 lbs for the motor and controlling hardware. The total weight should come in 400 lbs over stock. Of course it's possible all of this will be for nothing... but we all need a bankrupting project don't we?
 

·
Registered
Joined
·
3,559 Posts
Fair enough analysis. Just don't forget that GM does have a wind tunnel, whereas our bricks are...bricks.

Bonus - in the divorce, cuz all you do is spend time out there with that thing, she & her lawyer will just see it all as a random pile of junk, not knowing there's $50 grand sitting there, so it'll also be a "store of value" 😂

Seriously - it's not like there isn't room in that thing to drop in another 85kWh because I was right and you was mistook 😛

I do think you should think about ditching that sketch 4WL transfer case & OD unit idea and feed it nice input RPMs in high transfer case gear with a proper speed reducer in front of it all.
 

·
Registered
Joined
·
9 Posts
Discussion Starter · #5 ·
Unfortunately my wife is a gearhead as well and knows good and well the value of everything in that pile. So im banking on her being equally invested in the thing for divorce not to be an option haha

Also wind tunnel does help the hummer a bit, but at the end of the day a sculpted brick is still a brick 😂.

Right now the ideal would be finding a model S or X with 100 kwh pack and swapping that in then putting more modules in later when I figure out how to make mismatched cells play nicely enough. Definitely gonna figure out a cleaner way to get gear reduction. If there was an after market gear set for the tesla drive units that would give me about 3:1 on the gearing that would work out great.
 

·
Registered
Joined
·
3,559 Posts
There's a dude here on the forum that's working on one with a yoke output. I forget his handle (I'll blame the LT Covid for that lapse), even though I ran across a posting he made earlier today.

Let me go look at the trail of crumbs...brb
 

·
Registered
Joined
·
3,559 Posts
ta da!


Gearhead wife...I need to get me one of those
 

·
Registered
Joined
·
58 Posts
So, what would be the correct motor choice to push a heavy vehicle like this one?
Teslas ain’t light and with a liquid cooled motor that could be had out of salvage, I’d have thought that’d be the choice.
We’ve all had dreams of electrifying a MBenz, a Caddy, or an old truck.
Blank sheet of paper: What motor would you spec for this app?
 

·
Registered
Joined
·
9 Posts
Discussion Starter · #10 ·
For this truck and most trucks in general where speed isnt the primary concern I would think a tesla LDU would be the motor of choice atleast with appropriate gearing. If not that than a 13" DC motor
 

·
Registered
Joined
·
3,559 Posts
UQM, BW, or Cascadia come to mind.

LDU is deep geared with two axle outputs via an open diff.

A company in UK offers a 4-ish to one gearset and limited slip that lets you place the LDU where the transfer case was as an AWD.

Some Land Rover builds here are using all this. But a Land Rover doesn't curb at 7200 pounds. It may run, just that it may not last very long.
 

·
Registered
Joined
·
9 Posts
Discussion Starter · #14 ·
Welp back to the drawing board for gearing. I know no matter what this will be an on going thing even after I initially finish it. No matter what I know the original NV273 T-case needs to stay with the the truck. I may use an SDU and an aftermarket OD/UD unit from Gear Vendors. If I'm going to get a wrecked Tesla to scavenge a battery pack, I might as well experiment with the motor and at least see how long it lasts.
 

·
Registered
Joined
·
9 Posts
Discussion Starter · #15 ·
I think what I may have to do for the sake of ease is retain the stock auto transmission but remove the torque converter, mate it direct to the input shaft of the transmission, and have an auxiliary pump. I would probably lock it in 1st for most daily driving and shift up to second if needed.
 

·
Registered
Joined
·
9 Posts
Discussion Starter · #17 ·
Lock it as in leave the gear selector in first so that it doesnt shift up. This would alleviate the headache of figuring out how to mate multiple input and output shafts and instead just the one for the motor to the transmission.
 

·
Registered
Joined
·
3,559 Posts
I think you should talk to your wife about all this 😛

There's only one input shaft and one output shaft (not counting PTO) on a Ford auto transmission. You have one alignment and that's the singular input shaft.

If you can make the pump work (non-trivial), there's an advantage to having the auto trans fully functional in a truck.

This isn't an ICE to where you need to rev the snot out of it to produce torque, but trading speed and torque at max horsepower is a nice to have.
 

·
Registered
Joined
·
9 Posts
Discussion Starter · #19 ·
I probably should haha.

I keep mentioning locking it in 1st gear though because I'm unsure if the trans is full hydraulic or if it's electronically shifted. Although I'm now remembering it's electronically shifted which makes controlling it much easier.
 
1 - 19 of 19 Posts
Top