That's right. You have to pedal much more with a crank drive bike. Your Cyclamatic is only 24v and 12 amps. There's a few hub-motored bikes with 36v and 20 amps, so that's two and a half times the power of your Cyclamatic. They are also much more efficient than your Cyclamatic because they have the power to keep the motor spinning in its most efficient zone. You should be able to do an easy 30 miles with one of these more powerful bikes and a 13Ah battery.
The Woosh Big Bear is probably the best bang-for-buck one. If you want comfort, go for the stepthrough version. It's like riding on a motorised armchair.
Other ones at the cheaper end are Ezee bikes, Kudos (look for the bigger motor). More expensive are the Volt X models, Oxygen MTB, KTM P (Panasonic) series and BH Emotion Neos. Finally, there's a plethora of bikes with big direct drive hub-motors like Giant, Kalkhoff and Annsmann, though I prefer the non-direct drive motored bikes.