initial cost cheap, quickly available and can use later on other projects. If I go with a AC system probably go with Lithium Iron cells. But that decision is further out.
1976 Fiat Spider 124 EV Conversion
Donner Car: 1976 Fiat Spider 124. Objective: Get my feet wet in the EV world and give me something to occupy some of my time in retirement. Challenges: Limited space, one spot in a three car garage in new house covered by a strict HOA. Advantages: Significant experience with large DIY projects. Built two vacation homes, built and flown experimental aircraft, car restoration, motorhome conversion and many other electrical mechanical systems. Background: Retire Lockheed System Engineer with AS and BS EE degrees. Age: 73. Location: Windsor Colorado
I want to build a low cost EV that is simple and performs similar to that of the 124 with the ICE. Range about 30 miles and used on relatively flat city streets with occasionally highway driving. Present design is 48 VDC Series Shunt Forklift motor of about 15 HP through the original 5 speed transmission and driven from a PWM controller from a 72 VDC LiFePo4 battery pack. No drive hardware obtained yet, still open to different technology. I intend to include significant instrumentation to monitor and document performance.
Additional information in "New Member" thread.
I intend to update this thread as I progress along with the project. Provide details on the design and lessons learned. I encourage input from the forum especially on simpler low cost approaches.
View attachment 133420
Striped down waiting for initial drive train.
I want to build a low cost EV that is simple and performs similar to that of the 124 with the ICE. Range about 30 miles and used on relatively flat city streets with occasionally highway driving. Present design is 48 VDC Series Shunt Forklift motor of about 15 HP through the original 5 speed transmission and driven from a PWM controller from a 72 VDC LiFePo4 battery pack. No drive hardware obtained yet, still open to different technology. I intend to include significant instrumentation to monitor and document performance.
Additional information in "New Member" thread.
I intend to update this thread as I progress along with the project. Provide details on the design and lessons learned. I encourage input from the forum especially on simpler low cost approaches.
View attachment 133420
Striped down waiting for initial drive train.
21 - 40 of 78 Posts
Big mistake.
It's not cheaper than a Leaf battery.
It weighs A LOT.
AC system has nothing to do with the battery choice...all batteries are DC
It's not cheaper than a Leaf battery.
It weighs A LOT.
AC system has nothing to do with the battery choice...all batteries are DC
I will check out the Leaf battery. Are you talking about a new or used leaf battery? Right now for my testing and learning phase I was just going to get $1,200 of lead acid batteries. Use them later to replace batteries that go bad in other cars because of the Colorado cold. Also, I am spreading out my costs over time. Yes, I know all batteries are DC, but I did not want to invest in a larger battery that would give me more range until I go to the AC system. What do you think of the Jaw coupling to the transmission? I went with it because of possible misalignment between the motor and transmission. For testing purposes I expect to do less than 100 miles. In that distance I should be able to evaluate ware.
Just an FYI:
In Lead Acid batteries there are (2) main types
...& they are designed for (2) very different uses
Starter batteries are used to "start" car engines (for short bursts)
...& Deep Cycle batteries are used to "power" electric motors (for long term/continuous use)
So, Starter batteries are not very "good" for long term power draws
...& Deep Cycle batteries are not usually very "good" for starting car engines
As another example, of available OEM Lithium battery packs, complete (used) 360V Chevy Volt Lithium battery packs are usually available for ~$2,000.00 on car-part.com
...& will "power" most DIYEV's very well
In Lead Acid batteries there are (2) main types
...& they are designed for (2) very different uses
Starter batteries are used to "start" car engines (for short bursts)
...& Deep Cycle batteries are used to "power" electric motors (for long term/continuous use)
So, Starter batteries are not very "good" for long term power draws
...& Deep Cycle batteries are not usually very "good" for starting car engines
As another example, of available OEM Lithium battery packs, complete (used) 360V Chevy Volt Lithium battery packs are usually available for ~$2,000.00 on car-part.com
...& will "power" most DIYEV's very well
Plan on zero misalignment between the two. Things you can't control, like temperature changes is why the coupler is there...not to enable a sloppy build. Jaw couplers suck, imo, but that's imo.
Check in with @windraver - he may have a set you can get. You won't pay much more, if any, than lead acid, you'll get more range, and a lot less weight which is a huge problem in any build.
Check in with @windraver - he may have a set you can get. You won't pay much more, if any, than lead acid, you'll get more range, and a lot less weight which is a huge problem in any build.
Thanks for the info. Still learning and have not made any critical decisions yet. Yes deep cycle would be better and I could use them latter in my RV.
Me tooStill learning
As for Lead vs Lithium in an EV
When I first converted my ElMoto (electric motorcycle), I used (4) 12V 35AH Lead Acid batteries (~140lbs.)
...& my range was only ~9 miles
Then, when I upgraded to a 48V 50AH Chevy Volt Lithium module (~50lbs.)
...my bike seemed "more nimble" from the (~90lbs.) weight loss
...& my range increased up to ~25 miles
The "Jaw coupling" ( Lovejoy type coupling?) needs both shafts it connects rigidly supported by bearings. The input shaft of the typical, common transmission, as it looks like the 124 has, is not well supported inside the transmission. You may have noticed it has a lot of side to side play. Typically, with an ICE, a carefully located pilot bearing is used at the end of the input shaft to align and support it. This pilot bearing is located in the end of the crankshaft or in the center of the flywheel.What do you think of the Jaw coupling to the transmission? I went with it because of possible misalignment between the motor and transmission.
The input shaft center line needs to be located within 0.005"(according to most manufacturers) from the transmission center line to prevent damage to the gears and bearings inside the transmission from misalignment. A Lovejoy type coupling will not support the input shaft and align it with this kind of accuracy. If you use one, be prepared to have to replace this expensive and rare transmission after a short period of time, as others have found with similar types of transmissions with poor input shaft support and misalignment issues.
So the Jaw coupling will not work for the long run. I was wondering why the need for the pilot bearing. It was always a pain to get the transmission slid into the flywheel even with a clutch disk centering tool. There are other 124s that have been electrified. How did they connect the motor to the transmission? The electric motor should have a front bearing. Will it support the side/up/down play of the input shaft of the transmission? I guess I need to get a ridged coupling and get as precise alignment as I can get. I will have to do a lot more research on this. This is why I have not spent big bucks yet on batteries and a motor system. Maybe the 124 is not a good candidate for my effort. Is there some way of telling that your misaligned? Noise or vibration? If so than maybe some careful left/right/up/down adjustment to tweak the alignment. Than match drill in place. The mechanical aspect is not as simple as I though. Well I will continue with the small motor and electrical setup I have for now with the Jaw coupling. Lots to think about.
One of the best options is to get a commercial adapter plate and coupling such as those made by can EV(possibly others) and supplied by their retailers: -- Vehicle Adapter Plates - - Motor Mounts / Adapters - MOTORS - EV PARTS . Although, I don't see one for a Fiat listed. An option would be to switch to a transmission from a more common vehicle (Toyota, Nissan, Ford, GM,etc.) that has an adapter plate and coupling available.
It looks like this Fiat transmission has a separate bell housing that has a machined circular hole where it aligns with the main body of the transmission. If so, this hole could be used with a dial indicator to align the electric motor output shaft on a fabricated adapter plate. This process is similar to how an ICE is set up: How To Align Your Bellhousing For Maximum Transmission And Clutch Life Unfortunately, most modern transmissions don't have a separate bell housing with this alignment option.
Rather than relying on the varying tolerances of regular bolts for repeatable alignment of the adapter plate on the bell housing, reamed holes with close fitting dowels should be used- just like the OEMs and the commercial adapter plates above use.
The coupling should have some provision for a pilot bearing or bushing to support and align the end of the input shaft.
It looks like this Fiat transmission has a separate bell housing that has a machined circular hole where it aligns with the main body of the transmission. If so, this hole could be used with a dial indicator to align the electric motor output shaft on a fabricated adapter plate. This process is similar to how an ICE is set up: How To Align Your Bellhousing For Maximum Transmission And Clutch Life Unfortunately, most modern transmissions don't have a separate bell housing with this alignment option.
Rather than relying on the varying tolerances of regular bolts for repeatable alignment of the adapter plate on the bell housing, reamed holes with close fitting dowels should be used- just like the OEMs and the commercial adapter plates above use.
The coupling should have some provision for a pilot bearing or bushing to support and align the end of the input shaft.
The jaw coupling will not work in the short run either. Wrong application.
You need a coupler and motor mount that's designed to be aligned as a system, ideally with that pilot bearing centered on the motor shaft.
There will be machining needed -- you are not going to pull a solution out of your HobbyKing catalog. Ditch the RC-car engineering.
Don't know what you mean by "rigid coupler".
You need a coupler and motor mount that's designed to be aligned as a system, ideally with that pilot bearing centered on the motor shaft.
There will be machining needed -- you are not going to pull a solution out of your HobbyKing catalog. Ditch the RC-car engineering.
Don't know what you mean by "rigid coupler".
Throw the gearbox over a hedge - its not needed - your problem with a low voltage system will be rpms - not torque
and a gearbox operates by gearing the motor down
When I was starting out I planned on using a Ford gearbox - but some quick calculation showed that I simply would not need the gearing
In "top gear" even with a small controller I was getting close to the "spin the tyres" torque
Without the gearbox you simply need to attach the propshaft to the motor - and with the motor where the gearbox used to live you will have lots of unobstructed space under the bonnet for batteries
and a gearbox operates by gearing the motor down
When I was starting out I planned on using a Ford gearbox - but some quick calculation showed that I simply would not need the gearing
In "top gear" even with a small controller I was getting close to the "spin the tyres" torque
Without the gearbox you simply need to attach the propshaft to the motor - and with the motor where the gearbox used to live you will have lots of unobstructed space under the bonnet for batteries
Not with the motor he's planned to use.
I appreciate all the input. All the comments give me plenty of options to investigate. At this point all I really have is a donor car and can go anywhere from here. Like I said I got a lot of research and thinking of how to go from here. Yes, I see the bell housing is separate. Also, based on all the input the motor is decision is not up in the air. My term "Rigid Coupler" refers to a coupler that is one piece connecting the motor to the transition. Maybe I am using the wrong term? Back to the drawing board.
I spent about 6 months designing the main systems on paper, and still I should have done a little more research on batteries before I bought. I have a good solution, but I could have done better.
They likely did what many conversions have done: they rigidly mount the motor to the transmission, and do not use any flexible couplings.There are other 124s that have been electrified. How did they connect the motor to the transmission?
Yes, it is common to mount a flywheel and clutch assembly on a motor with no support of the shaft other than the motor's own bearings, and to pilot the transmission shaft in that assembly. Don't assume that this will work with every motor, but it typically works with motors based on industrial designs (including old forklift trucks) with protruding plain shafts.The electric motor should have a front bearing. Will it support the side/up/down play of the input shaft of the transmission?
Yes, that's the general best practice. The coupling can have rotational compliance (like the spring centre of a clutch disk), and may slide axially (depending on design details) but not radial compliance.I guess I need to get a ridged coupling and get as precise alignment as I can get.
There's nothing unusual or especially difficult about the 124 as far as connecting a motor to the transmission is concerned.Maybe the 124 is not a good candidate for my effort.
That's a common situation: people with electrical experience don't realize that the mechanical parts are not trivial; people with mechanical experience don't realize that the electrical parts are not trivial. Software people don't understand high-power and high-voltage electrical issues, while electrical or electronic hardware people don't appreciate the complexity of software systems. Even when working in their own fields, people don't anticipate that their own experience might not completely cover new applications.The mechanical aspect is not as simple as I though.
I don't think that's advisable.Well I will continue with the small motor and electrical setup I have for now with the Jaw coupling.
More specifically, the input shaft is very well supported by a bearing right beside the only gear on the shaft... but there is only that one bearing, so nothing in the transmission really keeps it in line. The pilot bearing at the tip of the shaft doesn't take much force (because it is so far from the gear), but it is critical for alignment. When the clutch is engage the pilot bearing doesn't even turn, because the input shaft turns with the engine or motor that is driving it - the engine or motor is providing the bearing function. Because it turns so little, the pilot bearing is sometimes just a plain bushing (but I wouldn't suggest doing that).The "Jaw coupling" ( Lovejoy type coupling?) needs both shafts it connects rigidly supported by bearings. The input shaft of the typical, common transmission, as it looks like the 124 has, is not well supported inside the transmission. You may have noticed it has a lot of side to side play. Typically, with an ICE, a carefully located pilot bearing is used at the end of the input shaft to align and support it. This pilot bearing is located in the end of the crankshaft or in the center of the flywheel.
Very important (I even emboldened it)That's a common situation: people with electrical experience don't realize that the mechanical parts are not trivial; people with mechanical experience don't realize that the electrical parts are not trivial. Software people don't understand high-power and high-voltage electrical issues, while electrical or electronic hardware people don't appreciate the complexity of software systems. Even when working in their own fields, people don't anticipate that their own experience might not completely cover new applications.
...& well said
^^ With no clutch present, the pilot for the input shaft can be a slip fit hole in the coupler design...the coupler, motor shaft, and trans input shaft never rotate relative to each other.
I sometimes lose track of which project is using which configuration. It is certainly true that without a clutch, the pilot location feature only needs a slip fit, not a bearing; it is a like a setup with a clutch in which the clutch is never released.
21 - 40 of 78 Posts
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