Think of it like a garden hose.
Amps is the size (diameter) of the hose
volts is the pressure
watts is the gallons that comes out.
more volts = more pressure. more amps needs a bigger hose (or wire).
with a bigger hose or more pressure you can (but don't have to) get more water (watts).
If you're filling a bucket and need 5 gallons of water with a firehose or a straw you still need 5 gallons, one just takes a lot longer.
So if you are trying to charge a battery you are filling it with watts (measured per hour, or watt-hour, or for a house killowatt hour ( thousand) kwh).
To run a 5 w bulb for an hour takes 5 watts. If you run it off a battery for 10 hours you used 50 watts of power, total. So to recharge the battery you need to put 5 watts back in.
Jill & Chris, Wills (14) Evie (11) & Toby our collie (5)
2011 Grey Wolf 28BH
2013 Chevy K1500 Crew w/ Reese StraitLine Dual Cam
Nights camped 2011: 11 2012: 18 2013: 12 2014: 12 2015: 13 2016: 3