CLASSIC CONVERSION: 1975 Toyota Corolla KE30

Technical discussion on converting internal combustion to electric
Post Reply
Clay Tortoise
Noobie
Posts: 6
Joined: Fri, 31 Jan 2020, 05:55
Real Name: Lachlan
Location: Hawthorn VIC

CLASSIC CONVERSION: 1975 Toyota Corolla KE30

Post by Clay Tortoise »

G'day everyone,

My first time posting in the forum as I'm now seriously considering converting my beloved Corolla (stock image pictured below).


I'm an aerospace engineer, but inexperienced with electronics and high voltage systems in particular, but keen to learn!
I have every intention of going to the next Victorian AEVA meeting and picking brains directly there, but in the meantime I'd love to hear your thoughts and considerations on my intentions so far:
  • I want to keep the car as original as possible, for this reason I'd like to keep the 4 speed manual gearbox. Original motor made 41kW @ 6000 RPM and 93Nm out of the factory, so looking for a motor that will slightly exceed those specs without destroying the stock box and differential.
  • Regen braking is very appealing as a mechanical brake upgrade would be a pain (and I want all the electrons I can get), therefore leaning towards a PMAC motor.
  • A usable range of 100km would be desirable, by my calcs this would require a battery size of about 15kWh.
  • Stock curb weight is 880kg, working to a budget of 1000kg post conversion. This points me in the direction of LiFePO4.
  • I'd love to build my own battery pack and I have done some research on available cells, best manufacturers I've been able to find are CALB, Headway and Winston but still unable to exceed 150Wh/kg. Is that unrealistic? Any other manufacturers accessible in Australia?
Finally, my burning questions:
  • How do I select a battery voltage? Is this driven by the motor selection?
  • Are there likely to be enormous tech advances (particularly in commercially available batteries) in the next 2 years that will make me want to cry?
  • Has anyone been able to successfully integrate a Type 2 or Chademo charger into a conversion? Is public fast charging feasible?
Much appreciated in advance

reecho
Senior Member
Posts: 717
Joined: Sun, 17 Apr 2011, 02:39
Real Name: Richard Baird
Location: Perth WA
Contact:

Re: CLASSIC CONVERSION: 1975 Toyota Corolla KE30

Post by reecho »

Awesome old girl....

"Has anyone been able to successfully integrate a Type 2 or Chademo charger into a conversion? Is public fast charging feasible?"

Type 2 AC charging is a snap. ChaDeMo DC fast charging is now doable if you use Orion BMS......BUT.....Your battery voltage will need to be in the 360V nominal range. While the ChaDeMo standard says the range is 50-500V, the Charger manufacturers got lazy and most of them in AU start from around 270V DC.

Here's a good video for inspiration... https://youtu.be/CzQNT2OTdf8

User avatar
jonescg
Senior Member
Posts: 3237
Joined: Thu, 21 Jan 2010, 23:05
Real Name: Chris Jones
Location: Perth, WA.

Re: CLASSIC CONVERSION: 1975 Toyota Corolla KE30

Post by jonescg »

Hi Lachlan, that's a beautiful specimen there. I used to drive a 1974 Toyota Crown. Awesome rig.
No difficulty finding a motor capable of those specs, and retaining the 4-speed box is more convenient anyway, despite the fact you won't be changing gears all that much.
Regen is always good - the extra weight means any assistance pulling up is welcome. Also, since the brakes are probably drum on the rear, you don't want to be working on them often.
Battery voltage decision will be driven by your motor / controller decision.
LiFePO4 is robust and safe, but not very energy dense. If you're interested in double the energy density of this I put together battery packs that might interest you. Given space is always a major constraint, high energy density is your best weapon. But, my advice is try to mount the drivetrain components as best you can before committing to a battery. These older cars had fuel tanks just behind the rear axle, which makes them less desirable for battery placement, but you won't have much choice.
I think most folks would find DC charging a bit too troublesome on a conversion, but 7 kW AC charging is entirely useful.
AEVA National Secretary, WA branch chair.

User avatar
brendon_m
Senior Member
Posts: 467
Joined: Sat, 28 Oct 2017, 11:00
Real Name: Brendon McCarrol

Re: CLASSIC CONVERSION: 1975 Toyota Corolla KE30

Post by brendon_m »

In that power area I found these https://www.ev-power.com.au/product/evkit-s6-80v-rfwc/
to be good value. The big benefit I found is they're power dense, 55kW/120Nm for 25kg. Biggest down side is system voltage limit is 100v. It might be a bit small for your application but it'll be close.
I did stumble on this site https://www.electricmotorsport.com/lvw/
If you fill in all the details about your project and possibly send them your first born then allegedly theyll get back to you with what you need.
Ive never used it or anything but if you are willing to subject yourself to spam it might be worth seeing what they say.

Clay Tortoise
Noobie
Posts: 6
Joined: Fri, 31 Jan 2020, 05:55
Real Name: Lachlan
Location: Hawthorn VIC

Re: CLASSIC CONVERSION: 1975 Toyota Corolla KE30

Post by Clay Tortoise »

Thanks everyone.

If you're interested in double the energy density of this I put together battery packs that might interest you.
I'm always interested in power density. What kind of $/kWh are we talking? At what point does a battery pack require cooling?

I'm considering designing and installing the drive train and going with a cheaper, smaller lead acid setup first just until all the gremlins are ironed out; then upgrading the pack down the road.

If I can manage 7kW on Type 2 then that would be great, I live in an apartment so I'll kind of have to rely on the public network.

User avatar
brendon_m
Senior Member
Posts: 467
Joined: Sat, 28 Oct 2017, 11:00
Real Name: Brendon McCarrol

Re: CLASSIC CONVERSION: 1975 Toyota Corolla KE30

Post by brendon_m »

Starting with lead is probably a waste. You would be better off finding a second hand lithium pack, even a heavily degraded one and using that for testing. Lead is heavy hard to get a lot of power out of and it gases. All of which would complicate the build and in the long run lithium will cost less. Lead is cheaper but it has a short life span both in cycles and in calendar life.

Or even a prius pack for testing could work well for cheap.

If you got your hands on an old leaf/imiev wreck you could pull the motor out and mate it to the corolla gearbox and use the pack as well to boot.
Best motors for a EVs are the ones that a car company has spent millions of R+D on

Edited for spelling
Last edited by brendon_m on Sun, 02 Feb 2020, 19:23, edited 2 times in total.

User avatar
jonescg
Senior Member
Posts: 3237
Joined: Thu, 21 Jan 2010, 23:05
Real Name: Chris Jones
Location: Perth, WA.

Re: CLASSIC CONVERSION: 1975 Toyota Corolla KE30

Post by jonescg »

Clay Tortoise wrote:
Sun, 02 Feb 2020, 16:34
Thanks everyone.

If you're interested in double the energy density of this I put together battery packs that might interest you.
I'm always interested in power density. What kind of $/kWh are we talking? At what point does a battery pack require cooling?
I've built packs from high power, modest energy density cells (>4 kW/kg, 160 Wh/kg) mainly for electric racing applications, and the range cells I used in the Prelude conversion were low power, high energy density (~0.8 kW/kg, 210 Wh/kg) which is perfect for cruising range. These are pouch cells which I've built packs form for years now. As a built pack with liquid cooling it's at least $1100/kWh. Yeah.

Otherwise I'm working on an 18650 cell solution which will have similar power (0.8 kW/kg) but better energy density (250 Wh/kg) and also liquid cooled, but will be cheaper. Final product will be some time away though, but hopefully less than $800/kWh. These will be modules about 750 mm x 250 mm x 75 mm in shape, and 12s (44 V nominal) and 120 Ah.

The real bonus to these approaches is you can built the right sized pack for the space available, rather than compromising on capacity or voltage because of space. Big drawback is time and money though.
AEVA National Secretary, WA branch chair.

Post Reply