Perhaps the leading case applying the doctrine of promissory estoppel to subcontractors' bids is a 1958 case decided by the California Supreme Court.3 In that case, a general contractor preparing to bid on a school project received a bid by telephone from a subcontractor for the paving portion of the job.
Basically, four different types of DC motors are used in industrial applications: series wound, shunt wound, compound wound, and permanent magnet. Several factors must be considered when selecting a DC motor for a specific application.
Most production ev's use an ac induction motor. Even DC ev's typically use a motor controller that breaks the DC into pulses. You are right though, the batteries currently store DC, but it's easily turned into AC through an inverter. Just like your house ac is turned into DC by your phone/laptop charger.