[Kilomike]

Hello all,

I'm a new member, but have been lurking for a few months and have read countless threads. I'm in the process of starting my first conversion and need some input from those with more background than I.

Quick background: I'm an engineer by school and trade and a machinist by hobby. I have a small machine shop in my garage and have friends with just about everything under the sun. I live in a hilly area and want to use the car for a 3 season daily driver.

The conversion:
Car: 1976 Triumph Spitfire 1500 (running!) with 3.89:1 final drive
Motor: AC PM Netgain Hyper9 w/ AC-X1 SME controller from EV West (planned)
Batteries: ~12kwh, ~100v Gen 1 Leaf Modules (planned)
BMS: Orion BMS (very open to others)
Charge: Open to suggestions
Timeline: Driveable by 4/19, drive all summer, rebuild/modify/change/restore next winter.

Questions:
Drivetrain: My biggest question right now is whether or not to use the stock tranny. I really like the idea of direct drive and the advertised Hyper9 specs seem to suggest it would work (as well as several threads on here). Is this reasonable or should just run the stock tranny for the near future? For those that have done direct drive with the Hyper9, how is performance?

BMS: I'm leaning towards the Orion series simply because of proliferation and support. Is there something better out there for a 1st build? I'm pretty comfortable with most aspects of the conversion, but BMS is voodoo.

Batteries: The leaf cells seem very popular and there are good datasheets available online, but I'm still not clear on what sort of discharge I can expect. I'm thinking I'll limit my peak current draw to ~500-600A (for multiple reasons). Can a 4P28S (since they're 2P2S modules) handle 600A peak and ~200A cont.? I've considered building an 18650 pack, but the cost would be more than double.

I think that's enough to get started. Any and all feedback is GREATLY appreciated!

Kilomike

 

[brian_]

Drivetrain: My biggest question right now is whether or not to use the stock tranny. I really like the idea of direct drive and the advertised Hyper9 specs seem to suggest it would work (as well as several threads on here). Is this reasonable or should just run the stock tranny for the near future?

Can you fit the HyPer 9 into the transmission tunnel, where the transmission is now, without structural modification? If you can, the gain of space in the original engine location for battery modules would be a significant advantage; however, if it doesn't fit there and has to be forward of the firewall then saving some weight would be the only benefit and you will be limited in torque to the wheels by not being able to use a lower gear.

For those that have done direct drive with the Hyper9, how is performance?

At this time, I think you'll be lucky to find anyone who has even completed a HyPer 9 build, let alone one without a transmission and in a car of comparable size to the Spitfire for a useful comparison.

 

[Kilomike]

From what I've read, I expect that the Hyper9 will fit about 9in back into the transmission tunnel. I haven't removed the old engine/tranny yet, so I can't say for sure. That said, I could easily modify the transmission tunnel if it was worth it.

And I figured as much on the Hyper9 builds. I've seen that several are using them, but I haven't been able to find any actual numbers outside of some calculations.

Thanks for the quick response! Any suggestions on BMS or what I should be looking for?

 

[brian_]

The conversion:
Car: 1976 Triumph Spitfire 1500 (running!) with 3.89:1 final drive

Have you seen any of the Spitfire conversions in the DIY Electric Car Garage? The Garage has been non-functional for a while, but pages are available from the Wayback Machine. Here are a few:

• E-Fire by Moltenmetal - build thread: E-Fire '75 Spitfire conversion: 1st build!
• Thistle by Baratong - build thread: '79 Spitfire Conversion
• 69 Spitfire by Mike Gahan

If you're interested, there are more and I can extend this list.

 

[brian_]

From what I've read, I expect that the Hyper9 will fit about 9in back into the transmission tunnel. I haven't removed the old engine/tranny yet, so I can't say for sure. That said, I could easily modify the transmission tunnel if it was worth it.

Getting the motor right out of the engine space would be nice, but all of the Spitfire builds that I've seen retain the transmission. The tunnel itself is one thing, but I would wonder about clearance between the frame rails. With the motor dimensions available, and the car in the garage, it should be easy to check.

Any suggestions on BMS or what I should be looking for?

Not my area, but I'm sure you'll get suggestions, widely varying in approach.

 

[Kilomike]

I've seen several of them, but I haven't been through the garage (it not working explains why I haven't found it!). I've read through Molten's thread twice as well several others that showed up when I searched "triumph" or "spitfire".

I've also looked on EVAlbum.com where there are ~12 spitfires. The common trend I've seen is LiFePO4 "brick" batteries and DC motors. I think this is mostly because they were done before AC was common and Lithium was put in production vehicles, but I could be missing something.

Am I correct in thinking that AC is a better option today? Regen seems like a no-brainer and there's a reason all of the big OEMs use them in the production vehicles.

I'm relatively new to all of this, so please correct me if I say anything dumb!

 

[Kilomike]

Here's a pic of the car from back when I picked it up. Didn't trust driving it 100miles, so it got to ride on the trailer.

 

[brian_]

I've seen several of them, but I haven't been through the garage (it not working explains why I haven't found it!). I've read through Molten's thread twice as well several others that showed up when I searched "triumph" or "spitfire".

I've also looked on EVAlbum.com where there are ~12 spitfires. The common trend I've seen is LiFePO4 "brick" batteries and DC motors. I think this is mostly because they were done before AC was common and Lithium was put in production vehicles, but I could be missing something.

Yes, the longer list of Spitfires in the Garage here shows a trend over time from lead-acid, to individual LiFePO4 prismatic cells, and just starting into salvaged production EV modules. Similarly, older builds are all DC, and some newer builds are AC induction (while DC builds continue); aftermarket AC PM motors had not appeared until this project, and I haven't seen any salvaged production EV motors or drive units yet.

 

[brian_]

Here's a pic of the car from back when I picked it up. Didn't trust driving it 100miles, so it got to ride on the trailer.

You got a hardtop with it!

 

[brian_]

Rather than assembling a longer list of previous Spitfire projects, I'll attach my spreadsheet as a PDF file. I would just put it in this post as a table, but vBulletin (at least as implemented in this forum) doesn't do tables.

And in case anyone is wondering why I have this spreadsheet already lying around... what brought me to this forum is that we have a Triumph Spitfire with a dead engine. I have an extensive list of potential engines to swap in, but an EV conversion was another option. It may still happen, someday...

 

[Kilomike]

Brian, Thank you so much for the guide to other spitfires! I'm very interested in Bottomfeeder's Sparkfire. It looks like the only one that's known to have went direct drive. I just found the thread and hope to get through it tonight.

Thanks again for all of the guidance! Any other nuggets of insight?

 

[brian_]

I'm very interested in Bottomfeeder's Sparkfire. It looks like the only one that's known to have went direct drive. I just found the thread and hope to get through it tonight.

Good catch - I had forgotten about that one that eventually eliminated the transmission. The story of his switch to "direct drive" was in a post in another build thread (Planning a new ev from a triumph spitfire - post #16). It was a late change, and I don't think it appears in his build own thread at all.

Sparkfire appears twice in my spreadsheet, to represent the initial and later versions.

Any other nuggets of insight?

My conclusion was that the Spitfire is an antiquated and flawed but fun package. Everything in it can be improved, but if you go down that route you have built a new and different car, so why start with a Spitfire? For instance, by the time the suspension is fixed and structure is improved it might as well be a Miata... and just buying a Miata would be cheaper and easier. The optimal compromise for me would be a powertrain replacement with as little effect on the rest of the car as possible, which means a transition between new stuff and old at either the input to the final drive, or the input to the transmission. What follows from that is that there is no point in trying to produce more torque than a well-prepared original Spit would have... not much more than 82 lb-ft into the stock transmission, or the corresponding stock non-U.S. input to final drive of 287 lbf-ft | 389 N-m @ 860 rpm shaft speed (first gear @ 3000 rpm engine speed). I also have little desire to do bodywork, so battery packaging into existing spaces would be a major issue and would lead to a moderate range... especially since I would refuse to stack cells in the nose or tail, to avoid ruining the vehicle dynamics.

But hey, that's just my thinking, and I haven't built it yet.

 

[Kilomike]

Thanks for the link to the thread! I probably would have never found that!

As for you comments on the spitfire in general, I completely agree and I think you hit the nail on head about some of my concerns. I chose the spit because of the styling and availability. I paid $2500 for a running spitfire with a clean body. I worry about the rear suspension, but at the same time my only intent is to use this to turn heads and drive the 12 miles each way to work. I'm not looking for crazy performance and I don't ever plan to run autocross with it. I just want it to be fun to scoot around town in. This also lets me get away with an approx 10kwh pack, which at ~250wh/mi, should give me a 30-40mi range.

Going with the Hyper 9, I do worry about blowing up the final drive/tranny. I'm almost certain it would destroy the tranny if I let it loose. That's another reason why I'm leaning toward going straight to direct drive. It looks like the final drive should be able to handle the 1:1 ratio torque (173ft-lb advertised peak vs your stated 287ft-lb stock load). Using the tranny may actually be bad in that regard as it would also allow over-stressing of the final drive in lower gears.

I did some more looking at the Hyper 9 specs and I think direct drive should work nicely. I sacrifice a little efficiency at low speed (<~20mph) but that seems to be the only significant detriment.

Hyper 9 curves: http://www.go-ev.com/PDFs/HyPer_9_120V_Performance.pdf

 

[brian_]

As for you comments on the spitfire in general, I completely agree and I think you hit the nail on head about some of my concerns. I chose the spit because of the styling and availability. I paid $2500 for a running spitfire with a clean body. I worry about the rear suspension, but at the same time my only intent is to use this to turn heads and drive the 12 miles each way to work. I'm not looking for crazy performance and I don't ever plan to run autocross with it. I just want it to be fun to scoot around town in. This also lets me get away with an approx 10kwh pack, which at ~250wh/mi, should give me a 30-40mi range.

That all seems reasonable to me. I would add that running an autocross (assuming you mean a pavement autoslalom, not a rallycross type thing!) is reasonable, too, since the "swing spring" design of the later Spitfire suspension calms down the swing-axle silliness. As long as you limit the torque to a reasonable level, pushing it around a course shouldn't be a problem for the car.

While searching to confirm that the 1976 would have the swing spring, I ran across an online discussion in which a Spitfire owner was proposing rear spring changes (to an earlier variant). A wise participant noted this:

The thing about a Spitfire is by the time you're putting down enough power and have enough traction that the spring rate is a concern, you have much more important things to worry about, like the differential, u-joints and axles.

This goes well with my thinking, that keeping the power - and the tires - reasonable means that you don't really need to worry about a lot of other things, in both drivetrain and suspension.

Going with the Hyper 9, I do worry about blowing up the final drive/tranny. I'm almost certain it would destroy the tranny if I let it loose. That's another reason why I'm leaning toward going straight to direct drive. It looks like the final drive should be able to handle the 1:1 ratio torque (173ft-lb advertised peak vs your stated 287ft-lb stock load). Using the tranny may actually be bad in that regard as it would also allow over-stressing of the final drive in lower gears.

You could program the controller to limit the current (and thus torque to the transmission and subsequently the final drive), which wouldn't take full advantage of the motor at low shaft speed, but wouldn't change high speed operation. Eliminating the transmission is an obvious solution, which wasn't so desirable with typical 9" DC motors but more feasible with the HyPer 9; however, it is effectively like driving in 4th gear all the time, while the final drive could withstand 3rd or even 2nd.

I did some more looking at the Hyper 9 specs and I think direct drive should work nicely. I sacrifice a little efficiency at low speed (<~20mph) but that seems to be the only significant detriment.

Hyper 9 curves: http://www.go-ev.com/PDFs/HyPer_9_120V_Performance.pdf

Losing the lower gears means losing the resulting torque multiplication and the ability to keep the motor in a more efficient speed range... which as you say only matters significantly at lower speeds.

If you run higher voltage, you have the option of using the HyPer 9HV, which (if given enough voltage) can provide a broader range of speeds over which full power is available. On the other hand, given the stock tire diameter (22.8" and 914 rev/mile for a 155SR13), and a final drive ratio of 3.89:1, a mile per minute (60 mph) would be 3555 rpm... so maybe all of the area of power improvement would be at speeds you'll never drive anyway without a transmission or other reduction gear.

I think this is the core of the single-speed problem: with enough voltage a modern motor can work well over a wide range of speeds, but the range is likely to extend up to 8,000 to 12,000 rpm. That means one ratio is fine, but it should be a much greater ratio than a typical final drive contains; in fact, production EVs all use two reduction stages to get the desired overall ratio. There is one production EV motor which was designed to work with a ratio similar to the Spitfire's 3.89:1, and that's in the Chevrolet Spark EV. Unfortunately, that's not the most common EV motor, it might be difficult to run with a readily available inverter (and the stock inverter would require hacking), and it's large in diameter. A HyPer 9 is a more practical choice, even though its speed range doesn't match the available gearing well.

The other really effective fix to the motor/gearing mismatch is to add simple fixed reduction gear to the back of the motor, instead of the multi-speed transmission. This can make a relatively small motor effective, by matching its speed range to the operating speed range of the car. Unfortunately, that's not a trivial bit of hardware: the only one I'm aware of is the ev-TorqueBox, which is a bit of overkill and not cheap (US$3500).

 

[Duncan]

Or you could throw the Hyper9 away and get a normal 9 inch forklift motor which will produce more than enough torque and rpms for a great machine at a fraction of the cost

 

[Kilomike]

Brian,

I plan to keep the stock tires, so it sounds like I shouldn't have too much to worry about with the final drive/rear suspension for the near future. I've been concerned about needing to do a complete rear-suspension replacement, but it sounds like I should be ok. If not then I'll cross that bridge when I get to it. I plan to limit the peak current to somewhere in the 500-600A range, so I think my concerns about the final drive are mostly settled.

As for the RPM range, that was the only reason why I even consider keeping the tranny. I figured I would only use 2nd and 4th or just leave it in 3rd. Realistically, in direct drive I'll probably not get past 4000rpm, which is really under-utilizing the Hyper 9 (and AC in general) capability.

Losing the lower gears means losing the resulting torque multiplication and the ability to keep the motor in a more efficient speed range... which as you say only matters significantly at lower speeds.

This has been my main concern, but looking again at the advertised curves for the motor, once I get to ~20mph I should be up around 87% efficient. I think that's good enough.

I've considered the HV Hyper 9 as well, but I haven't really seen the benefit. since I only want an ~10kwh pack, and the leaf modules are ~60Ah 7.4V each so a 2P14S pack of modules will give me ~104V and 120Ah (~12kwh). I can go higher voltage, but it really just gives me a bigger pack that I don't necessarily need. I am probably going to up to ~120V though just because the only real cost difference to do so is the bare modules.

Real quick on the battery. This is where most my research has focused and it seems like the Leaf modules are both the easiest and most cost effective to work with. I can buy the bare modules for ~$150/kwh which seems to blow everything else out of the water, but I am worried about their peak draw capability. I heavily considered building a custom 18650 pack, but not wanting to use salvage cells puts just the cell cost north of $3k for a barely 10kwh pack. And that doesn't even consider the HUNDREDS of hours to actually build the pack! I haven't looked hard at other production EV packs, but from what I've seen the leaf modules are about the easiest to get and work with.

Lastly, back on trying to match RPM to gearing, I have considered building a custom fixed ratio tail for the motor. Something like 1.25:1 which would let me use a lot more of the Hyper 9 capability. That said, it doesn't do me a ton of benefit at low speed, so I don't think it's worth it. And I have no idea yet what it would cost, just in materials, for me to build such a tail. I've looked at the ev Torque-Box but I think it is both too big and too expensive for this project. Total EV conversion cost I expect to be $8-10k. An additional $3500 just doesn't seem worth it or necessary.

Duncan,

Using a DC forklift motor is actually where I originally started on this project. I was inspired by the super cheap conversions on youtube. But I haven't had much luck finding a usable motor. Local craigslist and such are an empty desert. Ebay has some, but anything under $1k doesn't have any information with it and I'm pretty gun-shy being a first timer. Things like advancing timing and inspecting the coils for over-volting/current capability is just a little out of my wheelhouse. I considered using a Warp 9, but at $2k+ (not counting controller) we're back up in the price range of the Hyper 9 IS package (~$4150 including controller). Plus, I like having regen capability, reverse on a switch (with no extra hardware), and less maintenance than DC. And I can't discount the benefit of having a company I can call if I have to for technical support.

I'm open to going back to DC, but I simply haven't seen enough cost benefit to outweigh what AC offers. And the Hyper 9 seems to just be the best AC package on the market at the moment.

 

[brian_]

As with other modern motors, there are performance graphs for the HyPer 9 showing output over the full speed range of the motor, given various supply voltage limits.

For the same supplier's brushed DC equivalent (WarP 9 or another size), Netgain provides only those silly charts resulting from clamping a brake on a spinning motor, so there is only (questionable) data from free-spinning speed down to something near the torque peak. Is there any useful source of objective data for the torque (or power) output of a "forklift" motor over the speed range which is actually used in a car? Or do people just assume that the torque and current from stall to peak torque speed are constant at the peak values?

 

[Duncan]

Hi Kilo

They take a bit of finding but there are lots of forklift motors out there for scrap metal prices - I have bought a total of four ranging from $100 to $200

 

[Kilomike]

Brian,

What you state is all that I've been able to find as well. At best I've been able to dig up a stall torque. Nothing about max RPM, efficiency, etc.

Duncan,

How much of an issue is advancing timing and brush maintenance? What other concerns are there with going DC? Saving ~$2k is definitely enticing. It does seem that they are somewhat less efficient than SRIPM AC (~80-85% compared to ~94%). I'm open to the idea, but I'm gun-shy to minimal data and not having the technical background with them.

Where do you find the motors at that price?

Another reason why I've leaned toward the Hyper 9 is it is IP67 rated according to EVWest's page. But now that I look at literature on go-ev.com I'm not seeing any such claim. The only thing I've found is IP54 (limited dust intrusion). If it is in-fact IP67 then that will help a ton, because I am certainly concerned about moisture under the vehicle. It rains almost every day here from late June through late August. The more I look, the more I find wrong on EVWest's page for the Hyper 9. The motor curves they show do not match anything that I've found in other literature.

Kevin (Kilomike)

 

[brian_]

Another reason why I've leaned toward the Hyper 9 is it is IP67 rated according to EVWest's page. But now that I look at literature on go-ev.com I'm not seeing any such claim. The only thing I've found is IP54 (limited dust intrusion). If it is in-fact IP67 then that will help a ton, because I am certainly concerned about moisture under the vehicle.

The HyPer 9 motor is made for Netgain by SME; Netgain is just the distributor (although EV West lists them as manufacturer). It is one of their "SRIPM" series. SME's web page for this product is a bit general, and I don't see any indication of the IP code rating, but you could ask them.

The more I look, the more I find wrong on EVWest's page for the Hyper 9. The motor curves they show do not match anything that I've found in other literature.

The more links in the communication chain, the greater the errors...

The motor performance graph shown by EVWest appears to be from Netgain, but is for 64.5 volts RMS at the motor or 96 V DC supply, which doesn't match the EVWest package description (of 120 V); it doesn't even look quite like the 96 V grapsh published on Netgain's website. The shape suggests to me that it might be for the HV motor, but it's not labelled that way and Netgain only publishes 120 V and higher for the HV. SME does not publish details for the specific motor which they supply to Netgain.