It seems like Michael Crichton was an EV enthusiast, and made sure to write them into the Jurassic Park series at almost every opportunity. I remember being pretty excited with the electric tour vehicles in the 1990 Jurassic Park book, especially since they were Toyota Land Cruisers.
It's interesting how the vehicles differed between the Crichton books and the Spielberg film adaptations: electric Toyota Land Cruisers in the first book and a single solar-electric Ford Explorer (in addition to the mobile laboratory) in The Lost World versus electric Ford Explorer tour vehicles in the first movie, and several combustion-engined Mercedes ML320s in the second.
I presume that the electric Ford Explorer tour vehicles in the first movie did not have traction batteries and obtained propulsion energy from the rail in the ground, but supposedly carried at least one 12 V battery to run the lights that shone down on Alan and Tim as they raced the Explorer down from the tree.
I'm a bit puzzled by the not-at-all subtle paint scheme on the Explorers, that probably cancelled out most of the stealth aspect of the electric drive train.
Camouflage seemed to be the focus in The Lost World, since the vehicles were painted dark green. It's kind of a shame that none of the vehicles in the Lost World movie were implied to be electric.
I was pretty surprised that the mobile lab in the Lost World book was described to use Nissan lithium batteries (I wonder how many kWh!), considering the book was published in 1995 (how early did Nissan announce its battery development?).
A questionable trait of the mobile lab in the Lost World book is that it is described to run only from the solar panels while in unobstructed sunlight. As it enters the tree cover, the instrument lights flash to indicate that it switched from using the solar panels to using the batteries. Although Crichton describes the solar panels as being ultra-efficient, I still highly doubt there would be enough solar power on the roof to move the mobile lab without batteries. And why transition? Cinematics, perhaps?