My bike's throttle is malfunctioning I think, or it's a battery slowly dying. I ride it 22 miles a day. I go up a steep hill that lasts for 1.3 miles long and it kills the battery. I have to shut off the bike for 2+ minutes to keep it going up to speed. When I get close to coming back home from work it's been slowing down lately while using full throttle. I can probably keep pedaling, but I'm a little lazy and like the speed of the full throttle. It usually goes about 22 miles an hour but is slowing down to 17-19 WOT. Is this the battery or is the throttle sticking? Anyone had issues like this and fixed them?