I'm a longtime fan of electric vehicles (EVs) as well as Plug in Hybrid Electric Vehicles (PHEVs), in all their variations.  When it comes to investing, I think the best way to invest  in on the growth of electric transportation is batteries, partly because pure play battery companies exist (although my top battery pick, Electro Energy (EEEID) , has been one of my poorest performers, in a classic case of a cheaply priced company getting even cheaper.

Given these interests, I was speaking to the President of Porous Power Technologies, a private battery components firm a couple weeks ago about the difference between batteries for EVs and batteries for HEVs.  Counter-intuitively, HEVs are much more demanding on batteries than are EVs.  

This is because most batteries cannot release much of the stored electricity in a short time.  In fact, the same fully charged battery will produce more electricity if discharged slowly than if it is discharged quickly.

Image source: MPowerUK

An HEV will typically have a much smaller battery pack than a pure electric vehicle, and so each cell will have to discharge faster to produce the same acceleration from the electric motor.  The same is true for charging times, so an EV's batteries will be able to absorb more energy from regenerative braking than an HEV's, all else being equal.  This is the reason Trinity was able to get better performance by adding ultracapacitors top their "Extreme Hybrid" drivetrain.

Where does this leave investors?  It depends on where you stand on Hybrids vs. Electric Vehicles.  If you think that Hybrid vehicles are going to continue to gain market share, and EVs will remain a niche market, you should focus on battery technologies with higher discharge rates, and on ultracapacitor investments.  If you believe that electric vehicles are going to take off and start taking market share away from hybrids, the slower (and less expensive) technologies will likely be better investments.

DISCLOSURE: Tom Konrad has an investment Porous Power Technologies. (Note: Porous Power is no longer taking investments from non-accredited investors.)
DISCLAIMER: The information and trades provided here and in the comments are for informational purposes only and are not a solicitation to buy or sell any of these securities. Investing involves substantial risk and you should evaluate your own risk levels before you make any investment. Past results are not an indication of future performance. Please take the time to read the full disclaimer here.