I was starting to research smaller EV platforms and I was looking at the Smart. I was looking for lower power and weight, and that seemed to fit the bill. Then I started learning about the Smart battery, which may or may not come with the car and is a Mercedes astronomical price. Then I learned that the batteries seem to tank themselves if they ever see an error and are non-servicable, send all sorts of codes back and forth to the car's motor controller, etc. I get that batteries are dangerous and I am not trying to ignore that, but I really don't want to end up with parts that grassroots folks can't make to work because the software won't let you.
In this day and age of motor swaps meaning you also need to get the gas pedal, what EV systems will let you run with whatever battery has correct voltage? Are there any swap friendly options? I am not talking about putting a different body on a Leaf pan, I mean buy a wrecked car, gut its useful bits, and go build something or put it in something. There are lots of comments on the board about, "that fill in the blank car would be great with fill in the blank EV powertrain," but do we have readily available tools and options to actually make that work?
I can't be the first person to ask the question, so I am hoping folks will chime in and we can start collecting info.
It may all be moot if you have to budget a couple grand a year to get new battery packs as they wear out. I don't know anybody that does not notice their cell phone battery declining in capacity after a few years or wearing out the only battery for their favorite power tool, so the similar stories from electric cars are not out of place. Even so, figuring things out may still be worth the trouble.
Just one point... modern EV batteries don't "wear out" every year or couple of years. They are thermally managed and can last the life of the car. These are not laptop or cordless tool batteries.
Here's a cheap EV that is made with used Chevy Volt batteries:
https://www.youtube.com/watch?v=eRnFzklXi4o
And here's a new GM "crate motor" from the Bolt with battery pack for EV swaps: https://www.thedrive.com/news/37354/the-chevrolet-performance-ecrate-is-here-to-make-electric-drivetrain-swaps-easier-than-ever
There are tools and options to make it work, with the easy button being conversion kits from the likes of EVWest. Note I said easy, not cheap.
A lot of the homebrew conversions that use parts from other EVs seem to use Tesla parts. I don't think you can use the whole drivetrain, but a lot of people seem to use the batteries and, if possible, the motors as well. Although for the latter, the easier-button seems to be to adapt an existing, non-Tesla motor to an existing transmission.
Motors and Batteries are the Engine and Fluids of the EV schematic. The challenge, just like with internal combustion is the controller/ECU. Most volume production controllers are fairly well software protected. These controllers go as far as managing the individual cells in the battery pack to maintain the long life expectations. The Tesla controllers have the over the air update feature, which can be used to effectively lock the controller if it is being used after a car is documented as no longer roadworthy (by whatever state/agency/etc).
The homebrew solution turns into a programming exercise not unlike writing your own version of megasquirt for EV systems. Brute force can get you a running system, but the level of sophistication wanted by some will require some effort.
I have driven some fairly primitive EV's and worked on a few others that were downright Dr Frankenstien contraptions. They are doable, but the range/life of the systems are much lower than the available production vehicles.
The best answer for GRM stuff in this category is to get a donor that is operational, but not cosmetically/otherwise mechanically great and move the entire system to the platform of your choice. Packaging is the challenge.
stafford1500 said:
The best answer for GRM stuff in this category is to get a donor that is operational, but not cosmetically/otherwise mechanically great and move the entire system to the platform of your choice. Packaging is the challenge.
I was talking to a guy who was building an extended EV and he said it was a problem added a couple feet of extra wire in the harness ,
that added resistance and the EV computer thought something was wrong !
Many problems you would not think of :)
stafford1500 said:
Motors and Batteries are the Engine and Fluids of the EV schematic. The challenge, just like with internal combustion is the controller/ECU. Most volume production controllers are fairly well software protected. These controllers go as far as managing the individual cells in the battery pack to maintain the long life expectations. The Tesla controllers have the over the air update feature, which can be used to effectively lock the controller if it is being used after a car is documented as no longer roadworthy (by whatever state/agency/etc).
The homebrew solution turns into a programming exercise not unlike writing your own version of megasquirt for EV systems. Brute force can get you a running system, but the level of sophistication wanted by some will require some effort.
These guys sell the solutions for motor controllers and chargers and are very knowledgeable: http://www.manzanitamicro.com/ They sell the controllers that were used in that $3000 EV MINI build I posted earlier in the thread.
These guys sell the solutions for motor controllers and chargers and are very knowledgeable: http://www.manzanitamicro.com/ They sell the controllers that were used in that $3000 EV MINI build I posted earlier in the thread.
Wait. I followed that link and it took me to the Zilla controllers, which has long been a gold standard, but their controllers are $2,750 and $5,000. So how does that square with a $3k build?
In reply to Kreb (Forum Supporter) :
If it's the build I'm thinking of, the builder bought a used controller.
BoxheadTim (Forum Supporter) said:
In reply to Kreb (Forum Supporter) :
If it's the build I'm thinking of, the builder bought a used controller.
So it's kind of like scoring that $400 LSX then?
Seems to me that we are close to the point when GRM DIY EVs will become relatively common. They're still a little scary, costly and befuddling to a lot of us. I've been thinking that Ghetocetting a Leaf would be good fun, but a cheap used leaf will typically only have a range of 60 miles or so left, so would have to augment the batteries - adding weight and complexity, so again, not quite the easy button.
It would be neat to have a Prius or Leaf body kit to make a small pick-up or delivery van ,
like the Truckla - Tesla but simple ,
in 5 years we will have some used VW , EV "skates" around to play with ,
I've heard a rumor that someone known here has gathered the parts (salvaged Leaf iirc) and has everything needed to put together a challenge budget EV.
Linky: https://grassrootsmotorsports.com/forum/grm/diy-ev-recommendations/160887/page1/
something I'm very interested in, btw. My dad thinks I'm a communist, but I really like the idea of EVs. And I LOVE the idea of an electric dirt bike.
BoxheadTim (Forum Supporter) said:
In reply to Kreb (Forum Supporter) :
If it's the build I'm thinking of, the builder bought a used controller.
Exactly. And the source I posted is people knowledgeable on how to hook it up and make it work, and are grassroots enough to actually help people. I spent a lot of time with these guys back in the day. Good people: Joe and Rich
In reply to barefootskater (Shaun) :
I am trying to do 60 to 100 HP range (willing to go lower for lighter) and 30 mile range or so in a 2000 lb car. Obviously more batteries at more weight would also be possible. I was looking at the Smart EV, which looks promising though top speed is limited to 79. I don't really like that but I could live with it if I had to. I am needing regen on braking. The Smart battery situation prompted this thread. It may or may not be a practical solution.
Do we have more things to be comparing notes on, now?
matthewmcl (Forum Supporter) said:
In reply to barefootskater (Shaun) :
I am trying to do 60 to 100 HP range (willing to go lower for lighter) and 30 mile range or so in a 2000 lb car. Obviously more batteries at more weight would also be possible. I was looking at the Smart EV, which looks promising though top speed is limited to 79. I don't really like that but I could live with it if I had to. I am needing regen on braking. The Smart battery situation prompted this thread. It may or may not be a practical solution.
Do we have more things to be comparing notes on, now?
Yes we do! I've got a lot of interest and I was going to start a thread on something similar too.
First, Here's an old thread of mine with links to the OpenInverter project where they've hacked the Prius inverter amongst others. Because of the "Black box" nature of most inverter software, inverters can be had for cheap and their liquid cooling and solid-state parts mean they tend to stay perfectly usable. The Gen3 prius stock can handle a 200 volt battery pack stock and per my napkin math can power an EV motor up to 115Kw.
Here's a list of cheap OEM Hardware.
Biggest problem for your grassroots EV- assuming you say, salvage laptop batteries and assemble them into Ebike packs or something similar- is going to be finding a motor and controller that work well and allow for real performance. Needing regen braking means you're stuck to brushless DC or AC motors of some kind and have to stay away from transmissions; a far more common brushed DC motor can work in regen, but only if the poles are physically flipped. There's good news here- most forklifts have gone AC. Bad news is tho, their voltages run 36 to 48 since most run lead-acids while a Tesla motor (Internal Permanent Magnet, 3-pole) runs 400v+. Voltage applies to speed, though there are tricks to make a "slow" motor spin faster that are pretty basic. They also, are far more expensive and their controllers are super proprietary.
I can just deluge information at you if you'd like, I've kind of found a lot lol
Deluge is fine. I am all for buying a donor car to get parts. I just want to make sure that if I mix and match battery packs that I don't run into a controller that is trying to get a handshake before operating. Thanks for the links; I will go through those.
I just wanna be there when Calvin Nelson makes his first pass in his $2000 electric drag Studebaker!
matthewmcl (Forum Supporter) said:
In reply to barefootskater (Shaun) :
Do we have more things to be comparing notes on, now?
most likely. I sold my beetle though so those ev dreams died. But I'm not sure how long I can hold out against the call of an electric dirt bike.
matthewmcl (Forum Supporter) said:
Deluge is fine. I am all for buying a donor car to get parts. I just want to make sure that if I mix and match battery packs that I don't run into a controller that is trying to get a handshake before operating. Thanks for the links; I will go through those.
Here's an old link from Tesla about the difference between Brushless DC and AC Induction motors. Some things have changed since- the Model 3 and Y use whats called "Synchronous reluctance" AC motor that uses electromagnets instead of permanent ones- but to summarize, Brushlesss DC was the E36 M3 for a lilttle while but has been replaced by AC in most areas because of the problems with starting torque. Until you get to drag-race levels where that aforementioned efficiency can be seen, the only other area Brushless DC is good for is small vehicles like Ebikes where their lack of starting torque isn''t noticed, and their lack of needing an inverter is a big deal for simplicity's sake- it's why an Ebike with a depleted battery has less top speed too. You can still find the Brushless DCs in electric cars tho, the Smart EV used one.
Controller Handshakes I think all depends on the device and controller used. The OEM stuff needs to be hyper-accurate with it's mileage and % remaining for buyers so they have a lot of math into battery temp, resistance and voltage to get as close as an approximation of discharge (There is physically no real way to know the "True" percentage of battery life; we can only get close) while aftermarket stuff from Curtis will just have things like cutoffs and positions for temperature sensors. The latter is just fine for us; monitoring battery life can be done easily and the Prius shows temperature controls don't need to go much further than air cooling, assuming you ain't fllogging it.
I should mention tho, there's very good reasons to still keep an eye towards any Brushed DC motor around. Only expensive and highly advanced AC Internal Permanent magnet motors can produce the starting torques that a brushed DC can and they're still plenty cheap.
Here''s an electric LoCost running one and it's build thread.
Another big bonus to Brushed DC motors- theoretically, if you had a cooling system to manage heat, bearings that were rated for this duty and "infinite" power, you could put any amount of power through one and have that be converted to turning force. Part of the glory of a brushed DC motor's simplicity is also in the more electrical power you put into it, the more is converted to turning- excess electrons can't go anywhere else until they begin welding metal. Guys who've made those motors do 1,000HP do so by insulating them as much as possible, moving the brushes, and replacing the copper wires on the stators; contrast that to turbochargers pushing 20+ pounds of boost and such!
