Closing the deal on a 2016 HD Heritage Softail Classic. 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 charger, camera system) I can use the specs 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.

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!

 

There is. I did it on my buddies bike but it requires a DC Amp meter. Hooked it up in-between the battery and the battery cable. Turned everything on and ran it at Idle, 1.5k RPM, then 3k RPM to simulate highway speed to see what the amp draw/production was. He then knew the amp he was putting in was not going to cut it without to much of a drain on the electrical system at idle or lower RPM. Confirmed when we installed the amp. Converted everything over to LED lighting allowing the added draw from the new amp.

You do need a DC amp meter capable of much higher amperage than any multi meter will provide. I used a 100 amp analog DC amp meter.

 

We can guess why the astronauts wanted to do such stuff, as they were in a life limiting situation, but why do you ask? There's no point writing a thesis on this topic if we don't know what you are going to do with the info! If you simply want to add more lights then tell us what you have in mind - it's unlikely you are the first to do what you plan.

 

Well, it can have its advantages to know what you are capable of upgrading on your ride as well as things you can change to allow more upgrades. Before I order this amp to run x number of speakers, navigation devices, lighting, and still allow for x style of riding if city with allot of stop and go, slow cruise, expressway, or sitting in parking lot showing off the upgrades. We all have various style of riding and what works for some may not work for others. If you have the tools and knowledge of electronics and common sense to leave some left over power that is generated to actually recharge the battery... you could maximize what you want to do.