I'm looking at a conversion for a Daihatsu Cuore, l700 chassis. Super quick summary, 2 door 4 seat, 700kg "super mini" hatchback. FWD layout, but chassis is capable of AWD, which is what my query is centering around.
Goals are:
a commuter that can cover an approx 60km round trip each week day, roughly 20km of that will be on 100km/h highways, rest in stop start, 60km/h stuff.
- I'm setting my minimums at 100km range, 120km/h top speed.
- Primary objective is performance in handling and acceleration, secondary is developing environmentally friendly alternative for my commute.
- I have other vehicles available for longer trips, so am willing to sacrifice range for performance as long as the vehicle is capable of handling my commute distance with a reasonable safety margin.
- Down the road I believe I would look at using partially degraded batteries for home storage from solar, so while I don't want to kill lifespan by overtaxing the batteries, I dont want weight penalties involved in over sizing the battery pack to accommodate future degradation.
My concerns at this stage are:
Over speeding the rear motor, I'm hoping that a control solution can be found that will transfer the load from the low geared rear to the higher geared front as speed increases, but am unsure how far a motor can be spun beyond its rated speed.
Motor selection. Cost is an obvious factor when doubling down on everything, so that is steering me towards a DC setup. By sacrificing on range requirements I'm also thinking that Regen and other major benefits of AC wont have the same value to my application as others.
Did briefly consider DC rear, AC front to try for the strengths of each type, but I cant really see a realistic way forward on that once practicalities of controllers etc come into play. Am keen on opinions though.
If I did go DC throughout, do folks have thoughts on benefits/drawbacks of mismatched motors? I'm thinking I'd want most of my torque from around 0-80, if 80-120 is achieved in an "acceptable" time frame by a smaller motor through higher gearing, I could be tempted if there is weight/cost savings to be had. Conversely I might have some opportunities to "over-boost" the rear motor and run it hot, with the knowledge that I have the front motor taking the load at mid to high speeds or when a thermal cutout comes into play.
Brief thought bubble also in back of mind is two smaller motors upfront connected direct to axle. Very high gearing ratio, but I'd have the rear to get it up to speed, think I'm opening a whole can of worms from a handling/stability control perspective which is steering me towards running through mechanical diffs. Again interested in opinions of the current state of stability control for the home builders. Are these just simple algorithms that transfer torque or hugely complicated? I flip flop between all the various scenarios I can imagine a car getting itself into at speed, needing extremely complicated control software to deal with each of them, to mechanical diffs aren't exactly intelligent decision making machines, are two motors with a lookup table in their control software performing basically the same function, and after that it's up to the driver?
Thanks all, apologies for long post.