EMPs would damage dinosaur juice drinkers, too. One of the biggest issues with all electric vehicles is their weight. An EV with a usable range (300mi/500ish KM) is going to be close to 5000 lbs - that's before you slap on armor and weapons (and that'll eat into the range). Recharge time (15-30 minutes) will be an issue, especially if you have drones hunting for targets.
In a few years there'll be lighter batteries with much quicker charge times (well under 10 minutes), but the technology isn't quite there yet.