Google Maps drains my battery even after I killed the app

I went on a holiday trip somewhere and a mapping program was needed. I turned on Google Maps, used it for about an hour. I killed the app, so theoretically it shouldn't have run in the background. Just another hour later I noticed that my phone had turned off automatically.

I tried turn it on with no success. After this - during my whole holiday - my battery didn't performed as it had done before. It might be because of poor coverage.

Then a month later I went to a not so nearby (20 some km) repair shop. I turned on GM again. My battery was charged fully. After just half an hour later, my battery had the percentage of 41. And again I killed the app, so it was not running in the background. I made some phone calls, and two hours later my battery was totally dead.

I am suspicious that it does not enough to kill the app but a restart is needed to save battery, beside that GM consumes energy a lot when it runs.

Does anyone experienced the same or similar, and can give advice me? Or did I set something wrong? Should I uninstall GM and use something else?

(All over this issue I like the app itself 'cause it quite accurate and shows the most updated traffic info and the best routes.)

thanks in advance.