[brian_]

I see that you've switched from the earlier plan of adapting the original LT rear suspension into a deDion, to using a trailing-arm or semi-trailing arm independent suspension (presumably from a T4 Syncro). As long as all of the bits have enough capacity for this heavier truck, this seems like a good plan to me.

Usually clearance between the suspension arms and the front of the Leaf motor would be a concern, but presumably in this case the extra width of the LT moves the arms apart enough to provide enough room.

It looks like the arms are entirely outboard of the subframe rails, the Leaf drive unit is entirely inboard, and the rails are parallel and equidistant from the vehicle centre line. Since the Leaf unit is normally offset to the right-hand side of the vehicle (with the long motor to the right, the short transmission to the left, and the plane between them about centred, placing the diff about on centre) either

1. the Leaf unit is offset to the right in the subframe, or
2. the Leaf unit is about centred, in the subframe, so shifted left of where it would be in the Leaf.

Which way did you go? It looks like #2.

Assuming that the diff is now left of centre, either

• the right-side halfshaft is longer than the left, or
• the Leaf has unequal-length halfshafts, despite have a roughly centred differential.

The photos are great, but it's a little hard to judge dimensions from them.

 

[brian_]

Very interesting. A van and a Leaf transplant. That could very well be the only road to a DIY EV for me (regulatory barriers).

This LT is a truck with a tray bed, not an enclosed van, but many are vans and either way it is a commercial vehicle. Tony, I assume that you mean that regulations would be easier to work with for a commercial vehicle, right?

The driveshafts? Are they a direct fit? Seems unlikely, maybe custom made?

I'm interested in the details, but they're clearly not directly from either an LT or the Leaf. The LT doesn't have an independent rear suspension, and the Leaf (aside from not having similar hardware on the wheel end as the VW pieces being used) is much narrower than the LT. The front track of a 2017 Leaf is 1,540 mm (61″), while the LT is 2.085 m (6 ft 10.1 in) wide at the cab and 2.14 m (7 ft 0.3 in) at the flatbed, so the track must be substantial.

 

[brian_]

I need a van with an elevator for a wheelchair in the back as my future means of transport.
Electric of course.
Because of strict regulations for the electrical parts I want use components and systems that have been declared road legal as part as a type approval.
Transplanting a drivetrain and the electrical system from a Leaf into an older type van (like a VW up to '91) with an elevator already fitted, seems to be the best option.

That makes sense. The easiest fit into a third-generation Transporter (T3) might be a small Tesla Model S/X drive unit, because that motor sits behind the axle like the VW engine - the Leaf wouldn't fit with the T3 suspension and structure because it sits ahead of the axle line. The LT has lots of room to work with and the suspension is being completely replaced, but something like a T3 doesn't have that kind of space, and replacing the whole suspension doesn't seem like a good route for easy approval in a highly regulated country.

Fitting an entire Tesla battery pack into a VW van is another matter. See Kevin's "ICE Breaker" project (Tesla drive unit into T1) for one example (of a small drive drive unit, and 3/4 of the battery modules), but note that a complete change in suspension shouldn't be necessary (especially in a T3).

One challenge with the complete powertrain from a production EV is that the system doesn't want to run with critical parts missing, which is likely to be the case. The approach used by some people is to replace the controller with one which they can program, but you would need to check if that meets the approval requirements.

On the other hand, a Leaf (or VW e-Golf) drive unit would fit in the front of a T4, fitting very much like the original transverse engine. There would still be the challenges of fitting in the battery, and making the control electronics work.

So I'm very interested to see how this conversion goes. For instance the driveshafts. Apparently, they don't pose a big problem for the TS, but I'm very curious how he solved it, since they are clearly not from the donor cars.

In addition to this project, Kevin's project and others have described building halfshafts which fit the drive unit one end and the base vehicle's hubs on the other end.

 

[brian_]

seen this?

VW Pickup with Nissan Leaf Motor install part 1

Although he hasn't really started the installation yet - it's really just a positioning mock-up... yes, that's the arrangement I was suggesting for a T4.

Of course, this is very different vehicle and installation from CanadaLT28's project... can we get back to that?

 

[brian_]

A little beginning for the air bag supports. The bottom clamp will have a 10deg or so bevel to take some stress out of the rubber.

Good - I've seen some terrible air spring mounting jobs, and it's good to see you doing it properly. Presumably this will place the end plates aligned and approximately parallel at full compression.

 

[brian_]

The bracket can be seen having a different angle to the support. The setup will have a much lesser angle when the weight is on it but it seems there is no way to eliminate it totally.

The best that you can do with a single-arm suspension like this is to have the end plates parallel at one specific height. The best compromise might not put that at the normal ride height, because it is probably more important to avoid damage at the extremes of suspension travel.

The other solution is to mount the air spring on a telescopic cylinder (normally a shock absorber) with the angle change taken up by the mounts at the ends of the shock, but the T4 arms are not designed for that... and most air spring don't use that setup, and don't have problems.

 

[brian_]

I now have both a leaf pack and one volt pack. I would like opinions on whether to leave the leaf pack in its case and put the volt pack in custom battery boxes that fit the truck better OR take them all apart and attempt to merge them in such a way as to have cells work in parallel.

I'm not sure that I understand both alternatives.

Is the first option to parallel the entire Leaf pack (96S2P of 33 Ah cells) with the entire Volt pack? They have about the same nominal voltage, but different capacities and seem unlikely to load-share ideally. Or is the first option to use one at a time, switching between them?

Is the second option to reconfigure the Leaf pack to place modules in parallel and then series them into a 48S set, and reconfigure the Volt pack to put modules or more cells in parallel and then series them into another 48S set, then put all of that in series? With the different capacities this seems like a problematic configuration. Or, is the second option to parallel two Leaf cells with a set (3 if the earlier Volt pack, 2 if the later Volt pack) of Volt cells, then put those mixed-source groups in series?

Modules are easy to connect in parallel with other modules, but the Volt modules are big (lots of cells) so it doesn't get even close to cell level parallel connections. Reconfiguring Volt modules at the cell level requires cutting of welds and making some sort of clamped connections. The Leaf modules are only 2S, and because they have a "middle" terminal for the BMS they can be paralleled at the cell level with only bolted connections. But I'm guessing that you already know that...

 

[brian_]

I should not be speaking in terms of cell level...

I do know that there is a "middle terminal" for the BMS on Leaf modules and the first thought I had (and I don't know how realistic this is) would be to take X number of leaf modules and combine them with X number of Volt modules to make one larger grouping which could allow me to use only the Leaf BMS, and then S and P the groups to get the proper output voltage.

Thanks, that's more clear - it's essentially the mixed-source groups that I listed last, but connected only at the module level.

All Leaf modules are 2S. There are glued-together module pairs to the later packs, but you can still make the electrical connection at the single module level. Gen 1 Volt modules are 6S and (mostly) 12S; Gen 2 Volt modules are 12S and 16S... so each Volt module could be paralleled with a suitable number of Leaf modules.

My concern with this would be that with no connection between the cell-level connections of the Leaf BMS and the corresponding points in Volt pack, there would be no monitoring of any imbalance in the Volt pack; one cell group in the Volt pack could be charged too high or discharged too low and the Leaf BMS would not be able to warn about it. Of course there would also be no balancing of the Volt pack (maybe okay - that's a whole argument of it's own), and if the Leaf BMS balances the Leaf modules then those Leaf modules would be discharged a bit below the Volt module in parallel with them.

 

[brian_]

Do the Leaf and the Volt use the same chemistry?

The Volt (both generations) use "NMC-LMO Pouch" cells (by LG)
The Leaf was (at least originally) LiMn2O4 (LMO) with LiNiO2... no NMC.

No, the two are not matched. They are different chemistry choices to suit different performance requirements and different cooling systems.

I agree that this is another reason not to mix cells from both sources in parallel.

 

[brian_]

This is all looking good.

... but at this point, all that is being used of the LT is the cab, right? It's basically a fully custom built truck, using a variety of production components from multiple sources, one of which is a VW LT cab.

 

[brian_]

WOne issue is that the rear track is 2040mm and the front is 1860mm. I am getting mixed messages about the handling characteristics of a wider track in the rear than the front. This is not a race car so I don't need to get 1g on the skidpad but I would like it to be stable.

Although this track combination is less common than having the front track wider than the rear, that's for practical reasons rather than handling; I see no inherent problem.

What matters is that the roll stiffness is balanced between front and rear, but the right balance depends on suspension geometry (including camber change with travel and roll centre height) and load distribution... and track dimensions. If the front and rear suspensions were identical in design it would be easier to compare and tweak them, but in this case they are not even similar (other than being independent and having VW logos cast into some parts ), but that's normal. For stability, just don't go with excessive rear roll stiffness; you don't want the rear to lose more traction than the front as a consequence of tire angle and loading changes while cornering.

 

[brian_]

The stock LT has an equal track as does 2-3 other trucks I have seen but as double wheel trucks "appear" to have a wider track, I will assume the suspension and frame is, as you say, flexible enough take the movement, I won't worry too much about that.

Many lighter trucks with dual rear wheels do have wider rear track than front (because the single-rear-wheel version has slightly wider front track, but the extra rear wheels tacked on the outside add significantly to track), although medium-duty and heavy-duty trucks actually have narrower rear track, because the effective tire centres are in the middle of those rear pairs.

This should be a suspension question, not a frame question: the ideal frame is infinitely stiff, and lets the suspension work. In reality the frame does take torque and does twist as a result, but that's primarily an issue with uneven ground (which happens regardless of relative track dimensions), rather than the reaction to cornering forces. Even for reaction to cornering force, the suspension roll stiffness is as important as the track dimension - with identical track front and rear there will still be torque on the frame, dependent of roll stiffness and where the body and cargo loads are attached to the frame.

My biggest issue is that the battery box will be in there and will have to be quite stiff. I may have to build in some capability for it to move a bit without flexing itself.

Yes, that's common good practice for mounting on truck frames. Three-point mounting is the straightforward (but not always practical) solution.

 

[brian_]

response posted in separate thread: VW LT truck and Leaf motor(s)