Battery not Charging - High output Alternator?

[Tezza_imp]

Having been playing with alternators lately, I had a look at the Honda schematic. It uses a delta wound job which produces a fair amount of current (approx 23 amps at 5000 rpm) if my math is correct. The charge curve for most 12volt motorcycle alternators are pretty much the same and they seem to reach about 90% of their output by 3000rpm and then fall off fairly linear below these revs. Considering that I have an older 4 cylinder car that only has a 40 amp alternator, 23 amps sound ok considering you have only half the number of things drawing current. If you were concerned about battery voltage and were considering connecting up any USB devices, one of these may come in handy.
http://www.ebay.com.au/itm/Double-USB-Ch...SwbYZXcjJm