How does one calculate available power? (Crosspost)
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Tourer
Joined: May 2017
Posts: 329
Likes: 56
From: Fulltime RVer, Wherever!
How does one calculate available power? (Crosspost)
Didn't get any replies in the Electrical / Lighting / Alarm group, hoping for a better response here.
Closing the deal on a 2016 HD Heritage Softail Classic (being delivered in a week, actually). I have plans! And you know what they say about the road to hell being paved with.
I'm a computer programmer, but I'm not an electrician (or a mechanic). Clearly I know what you can certainly overdraw the available power in a system, but what I don't know -- how to calculate that information in advance.
Stock specs for this bike say that the system puts out 439 watts at 13 volts. Okay, good starting place. But various components (headlight, fuel pump, etc.) obviously utilize some of that juice thereby decreasing the available power and I really don't have the specs on those individual components or even a list of all the items that might be utilizing power like the EFI computer, etc.
Is there a way to measure the currently used power of the bike before adding additional electronics to it? For example (and this is a complete guess), if the bike produces 439 watts, how do you measure that the running bike is currently drawing 250 watts leaving the calculated 189 watts available? Then, as I decided to add anything (LED lights, phone chargers, camera system) I can use the specs individually on those to determine the additional draw.
I remember watching Apollo 13 where Gary Sinise is using the capsule's duplicate (and spouting amperage numbers) to determine that there was only (x) available power for the guys up in space to utilize, and required shutting this and that off first. (Of course their result was typically "too much, blown".)
I'm sure this will involve some sort of multimeter (yay, Harbor Freight), but is there a procedure for these sorts of things? I can look up the formulas, but I can't seem to find a good online article or discussion that explains how to take the measurements or what best practices are.
Thanks for any help, folks!
Closing the deal on a 2016 HD Heritage Softail Classic (being delivered in a week, actually). I have plans! And you know what they say about the road to hell being paved with.
I'm a computer programmer, but I'm not an electrician (or a mechanic). Clearly I know what you can certainly overdraw the available power in a system, but what I don't know -- how to calculate that information in advance.
Stock specs for this bike say that the system puts out 439 watts at 13 volts. Okay, good starting place. But various components (headlight, fuel pump, etc.) obviously utilize some of that juice thereby decreasing the available power and I really don't have the specs on those individual components or even a list of all the items that might be utilizing power like the EFI computer, etc.
Is there a way to measure the currently used power of the bike before adding additional electronics to it? For example (and this is a complete guess), if the bike produces 439 watts, how do you measure that the running bike is currently drawing 250 watts leaving the calculated 189 watts available? Then, as I decided to add anything (LED lights, phone chargers, camera system) I can use the specs individually on those to determine the additional draw.
I remember watching Apollo 13 where Gary Sinise is using the capsule's duplicate (and spouting amperage numbers) to determine that there was only (x) available power for the guys up in space to utilize, and required shutting this and that off first. (Of course their result was typically "too much, blown".)
I'm sure this will involve some sort of multimeter (yay, Harbor Freight), but is there a procedure for these sorts of things? I can look up the formulas, but I can't seem to find a good online article or discussion that explains how to take the measurements or what best practices are.
Thanks for any help, folks!
Advanced
Joined: Mar 2015
Posts: 89
Likes: 20
From: Alabama
Just a thought...you will note that your alternator develops power on a curve and the output is regulated. It starts at near zero at some low RPM and increases to a point referred to as "cut in" where the regulator begins doing its job. I don't have the performance curves for various systems so can't give you hard data. The point is that you don't have max wattage available at idle and probably not until something like 1500 or 2000 RPM. Whatever load you choose to add you need to consider if it will be required at idle.
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Tourer
Joined: May 2017
Posts: 329
Likes: 56
From: Fulltime RVer, Wherever!
...note that your alternator develops power on a curve and the output is regulated. ...you don't have max wattage available at idle and probably not until something like 1500 or 2000 RPM. Whatever load you choose to add you need to consider if it will be required at idle.
Any thoughts, though, on how to measure the current draw without knowing all current items' specs?
Cruiser
Joined: Aug 2005
Posts: 185
Likes: 6
From: Lufkin, Texas
Take a current measurement at full load. Once you have that figure, multiply it by the nominal voltage of the system and you have wattage.
Generally, people use "amp clamps"type meters, because they dont require you to open a circuit to measure. When measuring current with a probe type meter you have to open the circuit and place your leads in line with the current flow, and most low end meters are going to blow a fuse at around 10A.
This isn't bike specific, but the information definitely pertains to where you are heading:
http://www.penntexusa.com/LoadTestAnalysis.pdf
Generally, people use "amp clamps"type meters, because they dont require you to open a circuit to measure. When measuring current with a probe type meter you have to open the circuit and place your leads in line with the current flow, and most low end meters are going to blow a fuse at around 10A.
This isn't bike specific, but the information definitely pertains to where you are heading:
http://www.penntexusa.com/LoadTestAnalysis.pdf
Thread Starter
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Tourer
Joined: May 2017
Posts: 329
Likes: 56
From: Fulltime RVer, Wherever!
Originally Posted by roughneck266;16217190...
This isn't bike specific, but the information definitely pertains to where you are heading:
[url
This isn't bike specific, but the information definitely pertains to where you are heading:
[url
http://www.penntexusa.com/LoadTestAnalysis.pdf[/url]
Road Master
Joined: Nov 2013
Posts: 1,239
Likes: 356
From: virginia
Look at the installation instructions for HD Heated gloves on the HD website, they have a chart in the instructions that show power available for accessories for the different models If you cant find it, drop me a PM and ill go find mine.
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