Current and power
Hi Chris,
All nicely covered above except no one seems to have pointed out that the 225W is the maximum output. Some bikes won't hit this until 4000 rpm. With so little spare power, I'd be careful how you run a 55W vest. On a trail where you are at walking pace and fifteen minutes before each stop, switch it off. Also, controllers use power, as well as the jacket the coil in a reostat is getting warm. Most seem small losses, but i've seen one that used a Scaletrix part that could have been used to toast bread as a sideline
For sake of completeness:
Volts = Amps x Ohms
Watts = Volts X Amps
If you don't know how much power (Watts) an item might use, get the Amp rating off the fuse and use the formula. Unless you have a big alternator you'll scare yourself unless you use a couple of fiddle factors. Assume the battery is only 11.8 volts and all fuses are over rated by about 2 amps and you'll be close but safe. Indicators, the horn, brake light and the starter motor can have their power use reduced to 10% of the fused value due to intermittant use. If you are short of the odd 5 W look for an LED tail lamp, they use next to nothing. LED indicators simply move the load into a resistor block, so you only gain the lifetime, not the power use.
Andy
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