Jason McNeil Posted September 9, 2015 Share Posted September 9, 2015 There's some debate about much weight savings potential there is in 16" eWheel. I took apart the motor on the IPS132 & weighed each element to try to understand where these reductions might come from. ComponentWeight%Rotor & Rim2185g24.69%Tire & Inner965g10.90%Stator2845g32.15%Arm & screws505g5.71%Covers1150g12.99%Pedals1200g13.56%Total8850g Tire & inner tube weigh just under 1kg, by sourcing a lighter tire, it's probably possible to get this down to around 500gmRotor, rim, tire & inner tube (I deducted the last two from the net weight). Here the permanent magnets are placed side-by-side without any gap between them; according to a hub motor specialist, this produces a sub-optimal flux field & also uses more materials for a given diameter Wheel, than with a calculated spacing. Stator & armature: the armature is composed of steel, without utter destroying the motor, unable to say how much this contributes to weight vs using aluminum. Close-up of the stator: quality of the laminated iron core looks reasonably good, so too are the copper windings.The two motor plates (one's underneath), is surprising heavy at 1.15kg. Equivalent strength carbon-fiber covers could be made weighing a fraction of this. Pedals & support pins: aluminum, 1.2kg exactly! Again, with a redesign/rethink, these could probably be made to weigh half this & still be just as strong. Support arm columns & screws, aluminum, 505gm. A couple hundred gm savings at most. 32 cell IPS132 battery pack with wires, connectors, & casing, but not BMS, which is part of the control-board. 1,520gm400Wh Li-Po pack, as used on the F400/111, 2,170gm. Conclusion: it should be possible to shave around 3kg from a 16" eWheel, without any dramatic redesign to the fundamental structure. Cost of replacing certain parts with carbon fiber might add another $100 USD to the construction, but there are grounds to believe there is a large section of the market who will pay for a corresponding 3kg reduction in weight; alternatively high-grade ABS/PVC plastics could be used instead.It will be interesting to see where IPS saved so much weight in the Zero, a Wheel with a 800W motor (sustained?) & 32 cells for 9.3kg is quite an accomplishment, if it lives up to the hype. Link to comment Share on other sites More sharing options...
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