# Thinking about converting my Jeep Cherokee XJ



## risinqsuns (Jan 10, 2022)

Quick bump since it took 3 days to approve the thread – and now I've disappeared in the abyss


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## Electric Land Cruiser (Dec 30, 2020)

Good luck! Check out my build as my chassis and goals are similar. If you really need your vehicle to live your life you might want to buy another one to drive or even convert instead. Sounds like you have a great lifestyle however!


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## risinqsuns (Jan 10, 2022)

Electric Land Cruiser said:


> Good luck! Check out my build as my chassis and goals are similar. If you really need your vehicle to live your life you might want to buy another one to drive or even convert instead. Sounds like you have a great lifestyle however!


Thanks! Already lurking around in your build thread  My idea was to basically build a test stand in the garage, putting together the entire system, preparing the coupling, all the mounts etc., and then just swapping things over within a few weeks. If that works, I don't need to have another car


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## asymptonic (Oct 14, 2021)

As a fellow XJ nut (1998, first owner), good luck and god speed. My plan is to keep my XJ stock ICE for long trips and add a converted vehicle for the nearby trips.


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## 2drx4 (Jan 3, 2022)

Where are you thinking you're going to put the batteries?


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## risinqsuns (Jan 10, 2022)

asymptonic said:


> As a fellow XJ nut (1998, first owner), good luck and god speed. My plan is to keep my XJ stock ICE for long trips and add a converted vehicle for the nearby trips.


Yes, I've also thought about that, but I prefer to have one vehicle to "do it all". Since I have quite some capacity in terms of weight, I could add plenty more batteries for longer trips later 



2drx4 said:


> Where are you thinking you're going to put the batteries?


For the beginning, the pack will sit in the engine bay. Depending on the motor, it's going to weigh around 50-80 kg.. so still 170-200 kg left for batteries to maintain the original balance (since I also have the tire carrier in the back, evens out the weight loss from the gas tank)


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## reiderM (Dec 30, 2020)

DC will be the cheaper route most likely, but you have to replace the brushes from time to time which can be a hassle. Also generally requires a more robust cooling system.

With AC you get more modern features like regenerative braking. The best low-voltage AC option is a hyper 9 motor kit. 

Either way, Tesla modules are your best bet for a lower voltage system with those range goals. You'll want to have at least 25kwh or so to hit your desired range. 5 Tesla modules gives you 28kwh, and that voltage matches the low-voltage hyper9. If you want to up the voltage a bit, you can use 7 Tesla modules in series for more capacity with the Hyper9HV.

The car I was originally planning on converting was a 96 XJ 2-door I bought for $1k sight unseen. The unibody rails were completely rusted away, unfortunate because it looked so nice. I love XJs.


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## remy_martian (Feb 4, 2019)

Your recommendation might work for a one-off, but this is a prototype, not a one-off.

Tesla S/X modules are a bad choice if he plans to offer kits in upcoming years, meaning a complete redo. The 10 year old Tesla module design will likely be discontinued in favor of their structural battery. 

The 3/Y modules make more sense, IMO, where one module more or less does the job and they're being produced like jellybeans.


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## reiderM (Dec 30, 2020)

Form factor of those modules is not conducive to putting batteries in the engine bay at all.


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## brian_ (Feb 7, 2017)

remy_martian said:


> Tesla S/X modules are a bad choice if he plans to offer kits in upcoming years, meaning a complete redo. The 10 year old Tesla module design will likely be discontinued in favor of their structural battery.


I agree - the traditional S/X modules are presumably still in production, but have already been replaced for the top version of the model range (the Plaid) with a different form factor using different cells grouped in a different number of modules... and that's even without using the long-promised 4680 cells or a structural battery design.

From the point of view of diversity of supply in the same form factor, the VDA 355 standard is about the only potentially long-term format (because it is an industry standard not unique to one EV manufacturer or module supplier), but in practical terms it may not be the most viable. Examples are the three modules of about 355 mm length offered by Zero EV and the "Energy" series of modules in the OX Drive line from Electric GT; the Jaguar I-Pace uses this format, as well as some Volkswagens or Audis.



remy_martian said:


> The 3/Y modules make more sense, IMO, where one module more or less does the job and they're being produced like jellybeans.





reiderM said:


> Form factor of those modules is not conducive to putting batteries in the engine bay at all.


They will certainly be more plentiful than the old S/X modules, but yes... they are way too long for most potential locations in a conversion. The only place they would fit in an XJ Cherokee without radical lower body modification would be in the rear seat and cargo area, eliminating the rear seat and requiring a raised cargo floor. They would suit some vehicles with a high floor and lots of empty space under it (SuperfastMatt's Jaguar Mk V uses them), but not a XJ.


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## remy_martian (Feb 4, 2019)

reiderM said:


> Form factor of those modules is not conducive to putting batteries in the engine bay at all.


Yeah...so what?

One down each side of the driveshaft tunnel and you're done.

Edit: on the bottom of the vehicle, not inside it. Between the frame rails.


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## brian_ (Feb 7, 2017)

remy_martian said:


> One down each side of the driveshaft tunnel and you're done.
> 
> Edit: on the bottom of the vehicle, not inside it. Between the frame rails.


That sounds good, but check the dimensions of those modules, add allowances in all directions for structure and housing, then crawl under an XJ with a tape measure and look for the space without cutting structure or removing needed components of the vehicle... I don't think you'll find it.

If two of them would fit, then I agree that for a system needing either 23S to 25S or 46S to 50S of 3.7 V/cell battery a couple of Model 3/Y modules would be great.


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## remy_martian (Feb 4, 2019)

I'm forcing them to think "out of the box" - this is not a car conversion AND the low volatge means only two modules. Of course, *if it fits*. I'm thinking it should. 

Integrating removed crossmember function into the battery box structure is easy -- there are two shear plates in a box.

There's plenty of other crap that can get stuffed into the engine bay and a frunk in a conversion could be a calling card.


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## 2drx4 (Jan 3, 2022)

remy_martian said:


> Yeah...so what?
> 
> One down each side of the driveshaft tunnel and you're done.
> 
> Edit: on the bottom of the vehicle, not inside it. Between the frame rails.


There is very little space there in a Jeep XJ. The vehicle is unibody/unitized construction, so the actual "frame" sectional height is only about 4" or so, with multiple stiffeners and mounts from the floor above protruding into this area. Also, if the 4wd is to be retained, which IMHO is the only point of owning a SUV and not a minivan, the bulk of one side of this under body area is occupied by part of the transfer case and the front driveshaft. On my big ugly offroad XJ I had trouble even getting a 2.5" exhaust pipe through the "empty" side, as I have full belly skidplates and did not want anything hanging down. Likewise, you wouldn't want your battery modules to hang down, as you probably don't want them damaged.

If a guys is willing to make significant body and structural modifications, one probably could cut the floor out of the cargo area and part of under the back seat, and build a new floor lower down, install the modules, and put a false floor over the top. Or clear out that space and install said modules from below. There is a crossmember in this area that the shocks attach too, and two other braces that are for stiffening the floor and holding the gas tank. All of this would need to be reworked, and at this point there would be no way you could consider this a kit.

Model 70, AKA Jeep XJ, unibody "frame" diagram.


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## brian_ (Feb 7, 2017)

remy_martian said:


> I'm forcing them to think "out of the box" - this is not a car conversion...


Of course it's a car conversion. In other places people call this sort of vehicle a "car", because that's what it is... specifically a station wagon with 4WD. It's not a heavy truck with straight frame rails sitting so high that you can crawl under it without jacking it up.



remy_martian said:


> ... the low volatge means only two modules. Of course, *if it fits*. I'm thinking it should.


Even one is unlikely to fit, but yes, if one fits it's possible that one would fit on each side... but the transfer case and front driveshaft make that very unlikely.



remy_martian said:


> Integrating removed crossmember function into the battery box structure is easy -- there are two shear plates in a box.


Well, sure... you could also remove all structure under the floor pan and build a whole new structural box. That's one aspect of what I meant by "radical lower body modification". And the uninterrupted single module from front to back in the Model 3/Y pack means that the ends of a box acting as shear plates are only at the end, leaving a long span with no crossmember.



remy_martian said:


> There's plenty of other crap that can get stuffed into the engine bay and a frunk in a conversion could be a calling card.


I agree - the other stuff that needs to be packaged is not a concern if the battery doesn't go under the hood.


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## remy_martian (Feb 4, 2019)

Sorry Brian. Too late to the party and you're regurgitating what's already been said, and the obvious.

You can't beat the post before yours - he even included the "frame" diagram


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## brian_ (Feb 7, 2017)

remy_martian said:


> Sorry Brian. Too late to the party and you're regurgitating what's already been said, and the obvious.
> 
> You can't beat the post before yours - he even included the "frame" diagram


Ah, if only I gave a shit what you think.

And none of this seemed obvious to you, remy...


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## remy_martian (Feb 4, 2019)

The "like" button got pushed by me before you posted. Then you liked it. That made it very obvious I agreed with what got posted. And then you did. A = B, A = C, therefore, safe to say... B = C

There was nothing more to say, though I suppose I could have paraphrased the excellent perspective, analysis, and resource that was provided with an agenda to steal some of the intelligence. But, not my thing. I was provoking thought, as I had stated, the thought process got laid out really well on why not. Even included the structural layout, with measurements 😳

After that excellent posting, restating what got posted already was a waste of electrons and pixels. 

There are now several dead salmon floating down the Columbia after going through that power surge you engaged in 😂 .....Trying to show B < C when B = C

Pointless after the math was already done.


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## risinqsuns (Jan 10, 2022)

Oh boy, you guys left me stuff to read 

Let's get into your posts:

Regarding DC/AC, I'm aware of the more intense maintenance for DCs and the regen advantages of ACs. The con of ACs is the cost.. a solution would be to go for OEM parts, but then we're at high voltage again. I think the main factor is to determine how easy regen would be for DC motors. I know that the ZAPI H2 controller offers this option. And as far as I read, it's in general possible on a Series DC motor with interpoles, as long as the brushes aren't advanced (correct?).

Another challenge would be to find a sustainable source for used DC motors that I could overhaul and then use for the kits. And since the motor characteristics are leaning towards higher torque from low rpms, this seems to be the better choice for 4x4s. But I still have limited knowledge in these topics, so any advice is welcome.

Regarding the batteries: Seems like I need to do plenty of more research. The ZAPI H2 96V controller can handle 120V max. as well as 600A. So in my simple thinking, I would need to get a pack that sits at 120V when charged fully, correct? In terms of BMS, I've read many opposing arguments.. wether I shouldn't even have one (I would then need to have LiFePo cells).. if it's the right choice to get something off the shelf (Orion 2) or rather put one together myself...

Regarding the battery position in the car, I think the sensible choice is to first stuff the engine bay. With the motor and accessories out, I lose about 280 kg.. the motor would weigh 80 kg max., leaving me with 200 kg. Just for rough calculations, 4 Tesla modules weigh around 120 kg.. leaving 80 kg of capacity.. with the gas tank removed in the bank, this should balance things out and make the car lighter.. keep in mind, this is just a first step for about 100 km of range.
Putting batteries under the car is not really practical because of ground clearance, damage prevention as well as water protection.

Since we've already started talking about potential "business" decisions for a potential kit, let me give you some more ideas where this should lead to:
My identified niche would be the opposite of high-end, high power conversions like most companies offer by now. I'm aiming for good overall torque/performance, realistic range and interesting pricing. So why not set up a kit with a DC motor, 100-200 km of range and total cost of 10-15k.. at least that's my initial idea. 

I know, a lot of chaotic thoughts, so please forgive me for that. I appreciate the effort for making informational posts, and am looking forward to new inspiration


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## reiderM (Dec 30, 2020)

Sounds like you have a pretty solid plan.

Regenerative braking on DC motors (from my admittedly limited understanding) requires a switching contactor and is relatively complex, especially if you're doing this more than once. The good news is that with a rock crawler, regen probably isn't very important anyways.

Another advantage of DC over AC: you can push loads of current thru them for brief periods of time if properly cooled. That's why people can use a seemingly weak forklift motor in a car.

You'll probably want 5 or 6 tesla modules to hit that range, but of course the peak voltage with 5 will be a bit higher than what is allowed by that ZAPI controller. Is there any reason why you're specifically looking at that controller? There are tons of great DC motor controllers for a wide array of voltages.

For BMS: of course heavily dependent on your battery choice. Orion makes a nice BMS, but it's pricey. The Dilithium BMS is also popular and a bit cheaper. If using Tesla modules though, the SimpBMS is probably your best bet (I know I might be a bit biased -- I sell them!). Much more straightforward wiring and much smaller in size, which makes it an especially good option if you anticipate you'll be converting a whole bunch of XJs:
SimpBMS Tesla Battery Management System For Tesla Model S/X Battery Modules | eBay

I don't think putting together a BMS with the features you'd need is feasible at your skill level. It's also not a part that you want to take a chance with.

$15k USD is a reasonable budget for the first one that you convert. If you have enough volume, you could probably get that down to $10k/vehicle easily.


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## remy_martian (Feb 4, 2019)

Your biggest problem will be defeating the "more range is better" and "I need 800km range once a year so that's the pack size I need" mentality


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## risinqsuns (Jan 10, 2022)

@reiderM I chose the ZAPI controller because they are based in Italy and have a German partner company (Atech), so support/sourcing of parts as well as shipping will be way easier. In addition, at least as far as I know by now, it's one of the best quality controllers... and, as I stated, they have the option to run regen for DC motors. So from my understanding, I don't need to have switching contactors anymore? Or did I get something wrong?

The XJ is not going to be a rock crawler, it'll remain an everyday car for all sorts of jobs. And since I live in the mountains, regen is actually a big factor with all the downhill opportunities to really get back some range.

You're right on the BMS. I wasn't really thinking about creating my own from scratch, but rather use single components instead of a off-the-shelf kit. I already looked at your BMS, great work! The thing is, again, that we also have similar approaches here in Germany, as well as in France or the Netherlands. So from a potential future business standpoint, it's probably better to source "local" systems. But we'll see 

Good thing you agree on the budget side of things.. I think one major problem of available EV conversions is the cost.. Sure, lots of people don't care about that when converting their beloved oldtimer, but I want to offer a cost-effective, sustainable package for the average 4x4 guy / hunter, that doesn't necessarily needs all the most modern bells and whistles... it just needs to be reliable and reasonably priced.

@remy_martian This could be a potential problem, but at the same time, my target group would be people with a different mindset... people that just want to get into EV and still have reasonable expectations (as well as limited financial resources (and therefore still driving old 4x4s instead of shiny new "offroad" SUVs, although, well, what's left of the original 4x4 spirit in new cars anyways))


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## 2drx4 (Jan 3, 2022)

reiderM said:


> Regenerative braking on DC motors (from my admittedly limited understanding) requires a switching contactor and is relatively complex, especially if you're doing this more than once.


I'm curious about this. I'd always just heard "it doesn't work, go AC" and that was it. Is there reliable contactors and controllers for doing this? DC motors are definitely far more available.


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## reiderM (Dec 30, 2020)

2drx4 said:


> I'm curious about this. I'd always just heard "it doesn't work, go AC" and that was it. Is there reliable contactors and controllers for doing this? DC motors are definitely far more available.


My understanding, which may very well be wrong, is that the positive and negative poles on the motor must essentially be switched when electricity is being generated with regenerative braking. 

It's more theoretical than practical. I remember reading about someone who did it and they eventually welded a contactor. 

If Regen is important to you, AC pretty much is the only practical option I believe.


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## brian_ (Feb 7, 2017)

2drx4 said:


> I'm curious about this. I'd always just heard "it doesn't work, go AC" and that was it. Is there reliable contactors and controllers for doing this? DC motors are definitely far more available.


Series-wound DC motors - in which the stator (field) and rotor (armature) windings are connected in series - are readily available. For regenerative braking the field/stator needs to be controlled separately from the armature/rotor, and with a series motor that would require contactors to switch the wiring plus an additional controller for the separate field... or just getting the right type of brushed DC motor in the first place, which is a "separately excited" (or "SepEx", or "shunt") motor, for which the controller has separate sections for the field and armature.


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