Load Testing

[BlackSheepLogic]

The specifications for my bike's stator is 70VAC+ ~400W @5,000 RPM which equates to approx 5.7A from the stator. The service manual does not however give me the efficiency of the Rectifier/Regulator or how much maximum power in Whatts is required by the bike and therefore available for use. I can measure the maximum current draw as well as the regulators voltage to calculate power used but what I'm really after is power available.

My though is to use a brute force approach, while the bike is using it's maximum current draw, loading down the regulators output using a load until the voltage drops down to battery voltage (~12.8V) in order to get the power available at both idle and at 5000RPM since it's not specified or easily calculated by other means.

My question is 12.8V (battery voltage) a good cut off voltage. Thinking about it maybe 13V would be better as it provides some safety margin. Interested in what others have used as the cut off point when doing this type of measurement.

[bogan]

You could test things that way, but just be aware running so close to its maximum capacity could shorten the lifespan significantly due to heat buildup. If you have the part number for the reg/rect and could figure out its output specs that would be the safest way I think.