[OhKaspian]

So I have this Jeep XJ that i bought for 2k about 5 years ago from a family friend that was a metal worker(hence the custom back)

i had a donor ICE engine that I was going to swap it to. but the shop that I had it at took the jeep motor out, sold it, closed the business, and the owner moved across the country.

So i have a shell thats been sitting around for years, and i figured this would be a cool build.


My plan hasnt gotten very far yet but some of the ideas ive had so far are:

• Build a battery box where gas tank is, up through the bed for easy access.
• I would like a dual/tri motor with the "single gear transmissions" (i dont know the actual name)
• I plan on building a Solar camper that will have panels on the roof and a large battery system so i would like to have a port on the back to allow the jeep access to the campers batteries to extend towing range

Your skill level with auto mechanics and fabrication

II have some mechanical experience, zero metal fabrication experience, some electrical experience. But ive always been kind of a jack of all trades and i pick up on things quickly with good instruction

The range you are hoping to get (how many miles/charge)

looking for about 120 miles to start ( my daily average driving is just under 100 miles)

What level of performance you are hoping to get

Dont really need to go above 80mph, would like to be able to tow

How much money you are willing to put into your project

As much as required, as little as possible.

What parts you've already considered, if any.
nothing yet

Any ideas, suggestions, product recommendations, instructionals, or just general feedback welcome.

 

[OhKaspian]

Why 2 or 3 motors and what motors?

I wouldnt think i would be able to get the towing power i need from a single motor would i? I havent chosen a motor yet

 

[OhKaspian]

Towing power for what? You move houses for a living where you need three motors?

What are you towing (incl weight)?

In my post i talk about my plans involving building a solar powered camper with a large battery backup system, so im assuming thats going to be pretty heavy. I dont have anything picked out yet, as I am just in the starting phase.

but some quick weight estimates
Truck now as a shell: 2,000 +/- lbs
Camper: 7,000-10,000 lbs (this is based on a range of campers of different sizes, but doesnt include the weight of the batteries and solar etc)

is 2 or 3 motors a lot? the few swaps ive seen for these always have dual motors. and tesla uses dual and tri motor configurations in all vehicles. I just figured i needed that many for this plan.

 

[OhKaspian]

In my experience, towing more than 2x or 3x the truck weight is asking for trouble. I doubt your little sawed off Jeep was ever rated to tow more than 7000lb. As soon as you hit 2x, things can get squirelly pretty fast in curves going down steep grades with trailer push.

Yeah I understand that. There's going to be a lot of other work done to the jeep increasing the weight of it.

You clearly havent done the math on your solar powered camper. A set of foldout panels means next to no battery at all. LED lighting means you use maybe 40W of light for 8 hours...that's 0.33kWhr of battery...one Tesla module has you in lighting for 17 days...55lb. That's with zero solar. A PTC would nominally run 2kW for 12 hrs at night. That's 300lb of battery

You're right I clearly haven't as I stated before that I haven't done any of the calculations on the camper yet. I was using the weight of the mid-size and the large airstream models as a basis for the weight.
The camper in my mind is going to have a fixed solar system on the roof of it and the battery packs in the camper are more so to extend the range of the Jeep while towing than they are to run the camper.

Get the tow weight goal to a max of 4,000lb and target 3,000lb. Being sloppy with mass has no place if there's an EV in the equation.

I don't think I will be able to get a camper in the size that I want / need at that low of a weight unfortunately

In the Cherokee, do you intend to keep the beam axles front and rear, or are you planning (or willing) to replace that with independent suspension at front, or both? If you still have an original beam axle you can only drive it with one motor, so with both original beam axles you have two motors at most. Motors mounted on beam axles are possible, and would certainly work, but are not desirable in car or SUV. A beam axle with two separate inputs (pinion shafts) to connect two frame-mounted motor to one axle would be interesting, but custom, strange, and not worthwhile.

My plan was to completely remove pretty much all of the components from the original Jeep including the straight axles and do independent suspension for each wheel. I figured that way I would have the room from the engine bay and transmission tunnel to mount a dual motor system.


Y'all, I have ZERO idea what I'm doing, I've just got a dream 😂😂

 

[OhKaspian]

Then you're probably pushing the design limits of the XJ for towing what you want. This isn't an EV problem in this case unfortunately. You have to take into account the other limitations of the vehicle for towing beyond powertrain.

What are the other limitations?

 

[OhKaspian]

Braking, frame strength for the hitch, relative weight of the towing vehicle vs the trailer (The XJ is nice and light), strength of all the drive-line components under load. Keeping any fluids in the driveline cool, which is a little easier in the EV. Presumably you'll have trailer brakes as well. Sure I'm missing a couple things...

So as far as frame strength and relative weight of the vehicle these are things that I had already kind of considered when I was trying to determine which route I was going to go as far as engine swap (I considered diesel and gas and more recently decided on electric)
With the Jeep being a unibody I was going to get a donor frame mounted underneath to add stability (also weight) And then the front and rear bumpers are already custom made steel heavy duty bumpers that add a considerable amount of weight. On top of that I planned on doing a steel exoskeleton and roof rack that are going to add weight too.

And so I've just got the body basically that I'm keeping and I'm going to be changing out everything else and upgrading and beefing up.

This is going to be a long-term build 😂

Here's a nice thread on XJ (non EV) towing: XJ towing capacity

Thanks I'll have to check that out.

 

[OhKaspian]

Ah, so you intended to build a custom truck, and set a Cherokee body on top of it. That's very different from converting a Cherokee, although the Cherokee body limits the truck to a size which is too small to reasonably tow several tons, on the basis of stability.

So you're thinking the length of the XJ even if stabilized is still too short to be able to efficiently tow a camper of any reasonable size.

Well that's going to throw a wrench into my plan I'd say 😂😂

 

[OhKaspian]

Ah, so you intended to build a custom truck, and set a Cherokee body on top of it. That's very different from converting a Cherokee, although the Cherokee body limits the truck to a size which is too small to reasonably tow several tons, on the basis of stability.

Also the extent of how much of that extra stuff I do was depending on how much I needed to do like if I don't have to do that stuff I'm not going to

I think for now I'll focus on the truck, and then when it's done see what I can tow and go from there on the electric camper


Does anybody have recommendations on motors, batteries, controllers etc? Or a link to some good detailed instructions/check list for an ev conversation?

 

[OhKaspian]

Again, the biggest problem is typically not the transmission itself, it's the clutch. Yes, a very low first gear ratio can be selected to make it easier on the clutch, and in a 13-speed heavy truck transmission that's fine, but in a light vehicle 5-speed that's an undesirable compromise. A high-capacity clutch could be used, but people don't want a heavy and long-travel clutch pedal. And then there's generally incompetent non-commercial driver which the vehicle manufacturer can't control (unlike the automatic transmission that they can), which may be the biggest factor.

The net result is that in a vehicle like a Cherokee, the towing rating will be lower with the manual transmission, regardless of what could be done with a different vehicle under different circumstances. In full-size pickup trucks, when they were still available with manual transmissions, even the manuals had high towing capacity... but almost no one wants to drive those things. The Cherokee is sturdier than a Freelander, but still basically just a car; it's not a commercial vehicle. Some Cherokees have the same transmission as some pickup trucks, so for some of them this isn't the vehicle's towing limitation.

The details don't matter to an EV conversion anyway, except that if a manual transmission is used the lower towing rating rated to the clutch can be ignored - the electric powertrain will become its own limitation, and no one will determine that for the builder. The strongest manual found in a XJ Cherokee is probably the New Venture Gear 3500, but even though it was used in full-sized pickup trucks it would be marginal for the load considered in this conversion... regardless of the clutch.

Would using a transmission increase or decrease the towing capacity versus not using a transmission in an ev conversation?

 

[OhKaspian]

You will have a transmission. Most EVs have a fixed-ratio (or "single speed") transmission, because the electric motor works acceptably throughout the vehicle's speed range without changing the gear ratio ("shifting"). Many conversions use the vehicle's original transmission only because that is the easiest method for converting those vehicles, but a multi-ratio (e.g. five-speed) transmission does provide the option to use a lower gear at low speeds and higher gear at high speed, keeping the motor closer to the ideal speed and possibly heating up less under heavy load (which would help reliability when worked hard).

Yeah sorry that's what I meant was the ICE transmission or the single speed.

I don't have any of the native power train unfortunately. So I was going to go the single speed option if I could financially, My backup plan was to use a gm donor transmission (people LS swap everything so the availability of parts is nice)