240;114149 wroteVery interesting build!
Maybe I'm missing something but I'm not understanding how the gearbox setup works.
Firstly - I thought that electric cars could get away without gearboxes? (ie the power is more 'linear' I suppose?)
Regardless of that - why a manual box over auto, and how does the clutchless system work with it?
Other question - is it your daily driver and if so, does it tick all the boxes that a daily needs to?
If not - are there issues with battery charge levels/longevity if, say, you let the car sit for a few weeks between driving it?
Thanks. Glad you found it interesting. As
@Philia_Bear said autos are pretty wasteful with the torque converter. Since the motor doesn't idle when you come to a stop, the only real need for a clutch is when you change gear. Also, if you have an auto you need to have constant hydraulic pressure which is maintained while the petrol engine is idling. With an EV you either need to then retain the torque converter and set it up so the electric motor runs at idle, wasting electricity, or you have to have an external hydraulic pump that saps power. Hence why most home conversions use a manual, with or without a clutch.
We always start out in 2nd gear and can stay there unless we are going to be driving at 80 kph or above. If that's the case, you just take your foot off the accelerator and gently slide the gear lever from 2nd into 3rd. The electric motor speed drops very slowly unlike a petrol engine, so the motor speed pretty much matches the gearbox speed if you time it right and the gear lever just slips into 3rd with no grinding or anything. With our big DC motor, the rev limit is about 6500 rpm, which suits the manual box ratios fine. Some AC motors run at a lot higher rpm but obviously the gearbox wouldn't like those high revs. You can go without a gearbox but the motor would draw a lot more current from a stop, and the acceleration would be very sluggish with our setup. For example if you start off in 3rd gear instead of 2nd, you definitely feel how it blunts the performance and you can see via the instrumentation that it's using a lot more battery power.
I did use it as a daily driver when I was still living and working in Melbourne. In my 11 km commute over the Westgate bridge I never changed gears out of 2nd as the traffic usually crawled along at 60 or less! I could also drive to the airport or for example down to Moorabbin for our Volvo meetings, so it was fine in that respect. Of course double the range would have meant we could have driven to places farther away, but I typically charged every other night at home so we could pretty much drive 60-70 km each day if need be. The battery tech we're using have a very low self-discharge rate. We went away for about 6 weeks and found that it lost about 5% charge in that time.
Keep the questions coming!
