Leaf Box is a range extender controlling load applied to engine via throttle control. It is easy to install, as it uses factory plugs. It delivers following extensions to standard Nissan Leaf:
range extender – it bases on adding „N-mode on demand” (aka glide mode) to D-mode, along with alternative torque delivery strategy (read below). Range extension is around 10% (ECO mode, 24 kWh battery). With normal mode Leaf Box is off.
regenerative force at D mode can be increased by about 20% (from 20kW to 24kW). If you have version of Nissan Leaf with B mode - lucky you. But I can have B-mode even in the basic version of Leaf.
max power of Leaf can be increased from 80kW to 83kW (option).
Alternative torque progression with LeafBox (proposal, tested on car) Alternative torque progression with LeafBox (proposal, tested on car)
Alternative accelerator pedal interpretation for efficiency
Until now all Leafs have simple “accelerator pedal (acc) position → power” transition. Position of accelerator pedal is converted to power demand immediately. This we can see at energy usage panel in the car, but I have verified that also with chassis dyno.
This method suffers from two negative effects:
Acceleration of the car is not stable at all. The car first accelerates better, then, falls down with acceleration – as acceleration is simply dependent on torque, and because car has almost constant power for any rpm and any desired acc pedal position – it is logical that torque MUST go down (see graph – thin lines in the big graph – torque of car (=acceleration) for various acc pedal positions (verified with dyno).
Some parts of our acceleration are not crossing optimal motor efficiency (red and orange areas). In some areas it is impossible, but of course everything can be optimized.
Accelerator pedal to power demand map from 2012 ECU (normal mode, not for ECO). Accelerator pedal to power demand map from 2012 ECU (normal mode, not for ECO).
I have prepared an alternative power demand curve (presented as bold line in the small graph vs. thin line with same color – factory) that promotes two things: more constant acceleration and more efficiency.
Constant acceleration is, in my humble opinion, something perfect for our Leafs. I understand that it is hard to describe, but all LeafBox samples I will start to send soon to testers will have this new characteristics added (and with option to switch it off back to factory type of power demand – so they can be easily compared). I have been driving for few days with this setup – it is so nice that now, when I press the pedal to some position – acceleration is much more stable. There is no rapid power demand, and power demand changes in time (as the power is now not constant, but rather torque is more constant). This is visible on the power usage panel.
Remaining more in the optimal efficiency area – this is more or less a “side effect”, as we have “constant torque” strategy instead of “constant power” strategy. I cannot directly say whether this will extend the range or not (or maybe a bit) because I haven’t tried this on my test route.
For acc pedal levels over 70% torque demand curve becomes more and more „constant power” type. For 100% pedal it is just factory 100% power line, not altered.
Below 30% of acc pedal I have used less flat torque curves (not shown on the graph) because of the need for a jump start at lights or cross-roads.
Nissan Leaf LeafBox feature of N-mode on demand. While driving in D-mode you can almost remove leg from acc pedal. LeafBox will set motor power to exactly zero (0 kWh) so you will be rolling without energy conversions. This increases efficiency with longer distance trips and is good for overall range (autonomy). Power gauge is visible on right side.