I swear by my H10; its never let me down. I tried a couple of battery jobs but never could trust them; just went off for no apparent reason even when not close to unit.
Some people say power for H10 is a problem, but I made a 480v-110v, 100va transformer pack with leads and a 110 receptacle to plug in the H10.
I've also had good luck with ultrasonic leak detectors. I once picked up the sound of a leak from 20 feet away from the evaporator coil with the cover still on the unit. The coil had a teeny scrape on the ubend from when the coil was installed; probably scraped it on the edge of the cabinet; barely visible and didn't even have any oil around the leak; barely showed up with soap.
Just last Thursday I located a tiny pisher on a TXV pilot tube; could barely make any bubbles on that one either.
JUST A LITTLE CLOSER AND THE LITTER BOX IS ALL MINE!