Oh, okay.
Anytime voltage is decreased with a given wattage, amperage goes up. Likewise if the voltage is increased with a given wattage the amps go down.
4000 watts / 120 volts = 33 amps
4000 watts / 24 volts = 167 amps
Of course the reason your only seeing 60 or so amps is because of the windings ratio of the chargers transformer.
60 amps x 24 volts = 1440 watts
Go here
http://micro.magnet.fsu.edu/electromag/java/index.htmland scroll down to such things as;
Faraday's Electromagnetic Induction Experiment,
AC Generator Action,
DC Generator Action,
Ohm's Law, (Watts can be construed as resistance at work.)
How a Transformer Works
I don't know. Maybe you know this already.
http://hermes.eee.nott.ac.uk/teaching/cal/h61sig/sig0001.html This wavelength is drawn two dimensionally. In real life or 3-D its more like a Slinky kinda strechted out.
http://www.free-ed.net/sweethaven/ModElec/acee/frm0101.htmIts interesting to note that the small portion of the electromagnetic spectrum we humans know is like a grain of dust to the planet Earth. Its a continuum.
http://www.geo.mtu.edu/rs/back/spectrum/Sorry. Getting off the subject. I'll let you digest this and hope that I haven't skipped to much. Its all kinda like that Star Trek movie, the one with the Whales. When Dr. McCoy ask Mr. Spock what it was like to be dead and then come back to life. Mr. Spock's reply was, "Without a common frame of reference I would be speaking in gibberish."
I've yet to get into harmonics and RMS voltages. I think I touched a bit about kvar - Kilo Volt Amps Reactance. Maybe next time.