Posts By: Jeffrey Jenkins

Regenerative braking: A closer look at the methods and limits of regen

All motors are generators, the old saying goes, with the caveat that few types are equally good at both modes of operation, and some are downright awful as generators (a classic example being the single-phase shaded pole induction type, used in myriad small appliances the world over). Fortunately, both types of AC motor commonly used… Read more »

A closer look at film capacitors

Plastic film capacitors relentlessly continue to take over many of the duties in EV power electronics that were once performed by the venerable aluminum electrolytic type, mainly because film capacitors exhibit much lower losses and have a much longer operational lifespan, especially at ambient temperatures in the 75-85° C range. The tradeoff is that film… Read more »

A closer look at energy consumption in EVs

When it comes to factors that affect energy consumption in EVs, the big kahunas are weight and wind resistance (aka CdA), but there are other factors that can have a surprisingly outsized effect and that tend to be overlooked, such as the use of climate control (AC, of course, but especially heat). Conversely, one factor… Read more »

A closer look at power factor correction

Power Factor Correction (PFC) used to be something that electronics manufacturers only grudgingly added to a product – usually because of complaints about breakers tripping prematurely, or to meet regulatory requirements in the EU – but these days PFC is showing up in more and more products. While one should never underestimate the ability of… Read more »

A closer look at wire in EVs

Wire is not the most glamorous of components, but it is the enabler of our modern society – especially of our even more modern mode of transport, the EV – and a surprising amount of technology and engineering goes into making, selecting and using wire. How wire is made The modern method of manufacturing copper… Read more »

A closer look at rare earth permanent magnets

Rare earth magnets have gotten a lot of coverage in the EV press over the years for being expensive – especially back in 2011 when a supply disruption in China sent the prices up anywhere from fivefold for neodymium to 20-fold for dysprosium over the course of a few months – yet they are still… Read more »

The technical reasons Tesla would limit supercharging speed, and other practical charging considerations

Recently, a bit of a kerfuffle kicked up when a Tesla Model S owner noticed that the maximum charge rate for his car on the Supercharger network had suddenly been cut from 120 kW down to 90 kW, apparently the result of too many fast charge cycles. Tesla’s explanation was, essentially, that many things can… Read more »

EV tech explained: What are the limiting factors of an EV’s regenerative braking force?

In many EVs, regenerative braking is limited by the manufacturer to a modest level, and usually offers little or no ability for the driver to adjust it (aside from the few cases in which regen is made proportional to the initial movement of the brake pedal). Is tepid regen braking the result of some sort… Read more »