[The_Sasquatch]

I have been reading build logs here for years, and I am pumped to start my own. This project has been years in the making, launched into motion by the fortunate circumstances.

The Chassis: A 1985 Dodge Ramcharger 2 door SUV. Built on the Chrysler AD platform, it shares a ladder frame and drivetrain components with every Dodge pickup truck built between 1972 and 1993... I purchased mine 4 years ago for 3000$, primarily for its relatively low rust frame and rust free(ish) body.

The Powerplant:
For the last three years my plan had been to use a Siemens 1PV5135 motor as the core of the new EV drivetrain, but I always hesitated because of the slow acceleration estimates I was coming up with in order to have a reasonable top speed. Bottom line, it was under-powered for a 5000lb truck, and I knew I would be disappointed with the result... the lack of a reasonably priced motor option stalled the project until recently.

Two weeks ago a fellow DIY EV enthusiast shared a link for a Smith Electric Box Truck being auctioned... I had to get on google to figure out what it was, but when I did I knew my drivetrain quest was over. I figured out how to place a bid, and this past Wednesday the truck was mine!

The drivetrain is a Enovo P120 motor / controller combo. There is very little information available online for this motor but what I do know is that it is somewhere between 60 & 120kw continuous (sources conflict) motor capable of accelerating a 22,000 lb box truck to 55mph using a 2:1 reduction drive and a 5:1? differential... plenty of power for a 5000lb on-road /off-road SUV. I have reached out in a couple of places for more information, but so far I haven't heard back.

The Batteries:
The truck I purchased was built with 48 x Valence U27-12XP batteries, in a 24S2P configuration... the odometer is just over 40k miles, with represents 400 charge & discharge cycles. I broke down the packs on monday and one module was flashing red and metered at 7.8v, the rest were green and in standby mode at 12.8v! I don’t think I have the space or weight capacity for all these batteries, but I do have a 16ft enclosed trailer/camper with a pair of aftermarket 4000lb axles, I may build a range extender pack in the trailer for long tows, Or I might just sell them to someone who wants a 80kwh solar storage battery and use the money to help buy a model 3 battery pack.

I will add photos as soon as I figure out how!

 

[jbman]

What did you pay for that truck? It sounds like it has most of what you need. Very cool! I'd love to see some pics.

 

[brian_]

I assume that this is from a Smith Newton.

The drivetrain is a Enovo P120 ...

"Enova", right?

I don't know anything about the P120 motor, except that it is an induction motor, also used in one generation of the Optare Solo bus.

It appears that both Optare and Smith switched from Enova to MagTec motors, as the Envoa company failed; MagTec is still operating.

I wondered if there was any connection between Enova and MagTec; I don't think there is, but in the search I found this interesting report:
“Medium Duty Electric Vehicle Demonstration Project” Final Technical Report
Anyone who says that EVs are inherently reliable, or wonders why companies like Smith fail, should read this.

 

[The_Sasquatch]

Good find with that report... It might have shared me off buying the truck! Fingers crossed all the components on mine work.

 

[tom3141]

There's quite a few of us in the UK with the Enova P90 motor and inverter system from Smith's smaller van the Edison. These are 90kW so I would guess yours is 120kW as you suspect.

There were a lot of the Edison vans being scrapped here so a bunch of motors were available very cheap. We didn't get the full system though so it was very difficult to use the inverter in it's original form. Most people I know of are using some form of the Huebner open source inverter as the control board. If you have the full system though I imagine it will be fairly straightforward to transplant it exactly as it is. I struggled to find any information out about either Enova or Smiths. I believe both companies no longer exist. Incidentally, Smiths HQ was only just up the road from me.

 

[brian_]

I struggled to find any information out about either Enova or Smiths. I believe both companies no longer exist.

Smith Electric Vehicles is dead. It was still attempting to make business deals in 2015, but appears to be gone now, with their website (smithelectric.com) dead since sometime in 2017, which corresponds to reports of the company's demise.

Enova Systems was de-listed from the New York Stock Exchange in 2012, and certainly appears to be long-dead.

 

[The_Sasquatch]

Update 1: Pulled the drivetrain and batteries

The truck had to be towed out of the Co-Part yard where it was purchased... I was incredibly lucky to find a heavy mechanics shop a few miles from the yard that was willing to let me park my truck inside their heated shop to dismantle it! I started by attempting to drive the truck, but the BMS was reporting a battery fault and the vehicle would not switch into drive... I didn't work too hard to diagnose the problem, I knew I was dismantling the truck, and the biggest unknown was the battery, so I started there. The shops forklift came in very handy for dismounting the battery pods, the forklift scale said 1050lbs, and the mechanic driving it said it was usually light.

Each battery pod consisted of 24 Valence U27-12XP modules wired in series for ~300v nominal. The modules were stacked in two layers of 12 below a top panel that acted as a mounting point for the BMS and HV disconnect contactors... I haven't worked out the schematic of all this yet, but it appears the passenger side pod was is the "master" pod, with connections to the drivers side pod as well as the High voltage DC bus connection to the charger and inverter.

I disconnected enough of the cabling to remove the top panel, and then disconnected one terminal at each battery after labeling each, so that I could eventually re-assemble the pack later if needed. 24 batteries pretty much filled the back of the vehicle I was using... moving them took a few trips.

I went after the major HV components next.

The Major High voltage components consist of a EDN CMP326-02 dual 6.2kw charger, an Enova Panther 120 inverter, and an Enova Panther 120 motor.

First the charger. The label on the side says 2 x [email protected] = 6.2kw... however, some of the documentation I have read on this truck states it was equipped with an 18kw charger, so maybe these 6.2kw chargers were pushed to 8kw with better cooling? Regardless, I labeled all the connectors, disconnected everything, and dragged the charger to my car. (Side note: It is very heavy, My back said I should have used the fork lift, but the shop was charging me an hour minimum each time I needed help)

The Inverter and charger were rigidly mounted together in a subframe that was then mounted on rubber engine mounts to the main chassis of the truck. With the charger removed, I was able to access the connectors on the bottom of the inverter. It was labeled, unbolted, and dragged to my car as well... surprisingly lighter than the charger.

The motor was next... and it was a mother to get out. The bolts connecting it to the driveshaft were extremely tight, and there wasn't enough room to get a proper air powered impact onto them... breaking them loose took me laying under the truck holding a breaker bar onto the bolt and a steel pipe onto the breaker bar while a mechanic standing next to the truck tapped the pipe with a sledge hammer. Once it was loose, lifting it out was easy with the help of the fork lift and a heavy chain wrapped around the body of the motor.

After the big stuff, I followed the heavy gauge wires from the inverter to the heater core and AC compressor. The AC compressor was driven directly by the Inverter, while the Heater consists of a 24v pump circulating a small coolant loop through a resistive heating element and into a cabin heat exchanger. the heater had a standalone DC/DC converter between the inverter and the heating element... I think it runs at lower than pack voltage. I decided to leave the AC compressor alone and take the heating equipment, primarily because my truck had the AC removed a long time ago and I don't miss it, but also because neither I nor the shop was equipped to capture the refrigerant correctly, and none of us wanted to breath it while we worked!

After all the EV specific components were pulled from under the truck cab, I followed every cable from these components, cutting zip ties until I could pull the wire bundles out without cutting any wires... all these will get rung out later to learn how everything is connected.

Most of them came right out but the main low voltage trunk bundle leads to a big bulkhead connector under the dashboard and branched off to the bottom of the cab under what I suspected to be the drive mode selector, so that is where I went next.

Unfortunately at this point I had only one more day remaining to work on the truck this trip... I would have loved to completely pull the wiring harness behind the dashboard, but there wasn't going to be time. Instead I focused on the EV specific components I could see: ignition switch, throttle assembly, brake pot, BMS CAN bus, Status indicator LEDs, drive mode selector, and HV disconnect safety switch. I pulled everything and traced their wires back to the interior of dash bulkhead connector socket.. which was glued in

I took a bunch of photos as I cut the relevant harness legs out of the interior of the bulkhead socket, but I would have loved to have had the mating connector, even just for testing.

At this point the truck had already been moved outside the shop, and I felt less bad spilling coolant on the shops gravel storage yard, so the last thing I did before I left the truck was pull the radiator and coolant loops for the inverter, motor, and charger. The Radiator had two parallel cores, with the Inverter and Charger shared a loop (Radiator core 1> Inverter > Charger > Coolant tank > Coolant pump 1 > Radiator core 1) while the motor had a loop of its own (Radiator core 2 > Motor > Coolant tank > coolant pump 2 > radiator core 2) with the loops overlapping at the coolant tank. My guess is that this is for increased flow rate through each device?

One of the battery pods stayed in Dallas with a family member who is going to use it for solar storage, Everything else I pulled went into a rental truck and then I drove home to Colorado.

My plan is to sell the truck as a rolling chassis, but it hasn't sold yet and is still sitting at the shop where I left it... as I ring out the harness, I am more and more considering figuring a way to keep the cab when I sell the chassis and box, so that I can go back and pull the rest of the wiring harness and learn what some of the unknown pins on the bulkhead connector lead to. If anyone wants a nice truck box at a great price as a storage unit or replacement on your existing box truck, and is willing to let me visit to finish tearing apart the cab, let me know!

 

[brian_]

Thanks for the description.

An interesting item is the gearbox - it looks like there is a single-speed reduction gearbox mounted to the output of the motor, with a single stage of gearing (so the motor and final output shafts are offset). Do you know the ratio of the gearbox?

 

[The_Sasquatch]

Thanks for the description.

An interesting item is the gearbox - it looks like there is a single-speed reduction gearbox mounted to the output of the motor, with a single stage of gearing (so the motor and final output shafts are offset). Do you know the ratio of the gearbox?

An enova datasheet I found said the stock option was a 2.56:1 reduction, but also says other reductions were available. I haven't confirmed the ratio yet.

 

[The_Sasquatch]

Update 3: I've spent the last few days getting personal with the wiring harness and my multimeter... Attached are thumbnails of the results, since it appears I can't attach non-images. Message me if you are interested and I can share the schematic file and spreadsheet. There are still large parts of the harness that need to be added, especially the battery pods & High Voltage cables. Both documents are definitely still a work in progress.

One thing I have already learned is that I miscalculated in assuming most of the control logic would be in the motor controller, and that I didn't need the entire in-cab harness... It turns out all the precharge and primary contactor control was being managed by a PLC under the dash which I assumed was only controlling cabin functions. I grabbed the PLC thinking I might sell it, but didn't trace the harness:/ Does anyone know if it is possible to retrieve PLC code in a readable format?

I think I have the precharge relay scheme worked out, tomorrow I am going to try to bypass the place, manually actuate the precharge relays, and hopefully spin the motor!

 

[brian_]

Does anyone know if it is possible to retrieve PLC code in a readable format?

That depends on the specific PLC and what you consider "reasonable", but there are standard programming methods for PLCs, defined by IEC_61131-3. You will need software to read the program, and you may even need proprietary software from the PLC manufacturer or commercial software with a driver specific to the PLC model, but once you can see it you should be able to deal with it.

 

[Electroddy]

Depends on which PLC. Some of the ones I used to work with, just used a standard serial port. The usual settings were 8 none 1. (go figure) Some used a terminal app, some were somewhat proprietary.

 

[The_Sasquatch]

Bench test success! I got the motor turning.

As I mentioned in a previous post, after getting everything back to the garage I quickly figured out that I didn't do nearly a good enough job documenting the cab schematic... My previous post about a PLC controlling the precharge was incorrect, based on bad assumptions, it turns out the precharge circuit is controlled by the Enova Controller directly.

I won’t go into all the details of the failed attempts, there were many dead ends... There was lots of struggle trying to recreate the cab wiring using incomplete photos, but I lucked out when one of the other truck buyers got into contact with someone who had a lot of information to share... even though both Smith Electric and Enova are out of business, were asked to keep this documentation off the internet, and in gratitude to this donor being so generous, I want to honor that request... reach out if you buy a Smith Truck and I can share it offline.

The documentation included a full wiring harness drawing and a functional schematic of the Enova system… using these, plus CAN logs from one of the functional Smith trucks sold at the same time, I was able to cut out the BMS and ECU and spin the motor tonight! It is a mess of wires, but it is actually less complicated than it looks.

Something interesting I accidentally learned after getting everything working is that the Enova controller doesn’t actually require any CAN messages to operate, if all the interlocks are in place On bootup it starts sending a CAN message with a drive mode request, if it doesn’t receive a contradicting response from an ECU or BMS indicating charge mode or standby mode, once the precharge circuit completes, it defaults to drive mode.

I consolidated the information regarding how to connect the inverter here in one image, hopefully this gets all the important details across… I would be very interested to hear if anyone with a Panther 90 is able to use this information.

Now that the drive system is confirmed to work, its time to start on the mechanical work… lift the body off the truck, pull the motor, build some battery boxes and motor mounts, swap in a divorced transfer case… easy, it should be done in no time... right?

 

[The_Sasquatch]

Update: Design Talk

Since securing the major drivetrain components I have been updating my design. Below is my current CAD model. The Frame dimensions are from the Factory Service manual, scaled and measured based on the (incomplete) dimensions it does provide. I have found it to be accurate within ~1/4" in the important dimensions, such as widths, overall lengths, and relative distance to the ground at key mounting points. Regardless of the accuracy, it will only be a guide for construction... when it comes time to cut metal I will be measuring the frame directly.

The motor, controller, and charger are in the same relative configuration as in the donor vehicle, so not much to talk about there. I have disassembled the gearbox and found that it has a SAE standard 10-1.5 parallel key spline output shaft. The plan right now is to directly mate the output of the gearbox with the transfer case. I plan to copy Damien of EVBMW and use a lathe to combine the spline socket of the output flange with the splined output shaft from my transmission to create a custom coupler. The front of the motor will connect directly to the Transfer Case Mount/Transmission tailhousing... This puts the rear of the motor almost directly above the rear motor mounts, making mounting pretty simple.

In the donor vehicle the controller and Charger bolted into a sub-frame that was then bolted to the vehicle frame as a unit... I have all the sub-frame brackets, so the obvious step is to fabricate flanges from the frame to match this sub-frame. I haven't measured this exactly but the sub-frame is narrower than the frame rails, so it should be straightforward.

The battery box is designed for up to six Tesla model 3 battery modules, and is going to be the major fabrication job. As you can see above, it is going occupy the space below the floor of the body and between the frame rails, essentially replacing several frame cross members above the rear axle of the truck. It requires giving up the rear seat footwell, which isn't a loss as I plan to lose the rear seat regardless. As shown it requires cutting 75" of the upper flange on both sides of the frame to create a wide enough space... I could skip this by making it 4" narrower, but that would leave me a few inches short of fitting a third stack of modules, and since the inverter is spec'ed to 425v, I might add an additional short module later to bring the pack up to 428 volts, so I want the space.

The box will be welded directly into the frame, replacing some of the rear cross members. For the box construction I am looking into using corrugated steel shelf decking in the bottom of the box... the corrugation would significantly increase the stiffness and provide protection in the case of an impact, without increasing the weight (I think) vs a flat sheet + manually added ribs.

The walls will be 1/4" where the frame rails were cut, and 1/8" above the frame rails. As shown, the box has at least 2" above the differential with the suspension compressed beyond the bump stops (I assumed the rubber stop has been lost and the axle is hitting the frame bracket). On the top side, I will have the choice of adding a ~1" body lift or trimming some of the stiffening ribs that exist below the cargo compartment floor.. My plan right now is to go the body lift route.

 

[The_Sasquatch]

Update:

Work is starting for real. Today I finished separating the body from the frame and began the process of lifting the body so I could roll the frame out... of course, minutes after beginning the lift an unexpected spring snowstorm rolled in. Work progressed regardless, and the body is resting on a rolling cart while the frame is now free to be stripped of its ICE components, painted, and retrofitted!

Since my last post I have also been working on packaging all the required components. My goal is to mount everything inside the engine compartment to the frame, so that I can test the rolling frame before I set the body back on. It turns out the frame rails on my truck are almost exactly the same width apart as the frame of the Smith truck, so I am going to be able to re-use the sub-frame almost entirely without modification. Below you can see the subframe supporting the motor controller (Orange) with the charger installed above it. The large blue box is the engine compartment envelope beween the fenders and below the hood.

The exact placement of the motor isn't completely defined, I need to make a better model of the transfer case and transmission tailhousing, and locate these more precisely within the frame... all of this should be done in the next few days now that I have easy access to the frame for measurements.

My batteries are also arriving next week. I figured out a way to fit all four modules from a long range Tesla model 3 pack, and placed the order with a salvage shop last week, Alpha Auto in Spencer NY. They have been great to deal with, and the owner told me they are starting to specialize in EVs... mine was the 2nd model 3 pack they had sold this month. The packaging would leave me concerned if I was planning on putting the pack into a Tesla, but I asked for it to be packed as narrow as possible so I could fit it in my trailer for transport from the shipping terminal to my shop.

Updates will be coming faster now, I have a personal goal of having this thing rolling by the end of June... I have all the parts in hand, its an integration problem now!

 

[Mean Gene]

How is this project coming? If you got it on the road I am keenly interested in the performance. I am in the process of obtaining a Smith with the same Enovo motor/controller. Any documentation you would be willing to share with me would be mucho appreciated.