Modifications; Introduction; Calculating The Total Electrical Load - Honda VT750CD ACE Electrical Repair And Modification

5.0 Modifications
5.1 Introduction
Most ACE owners are in love with their bikes. We didn't just buy them because we wanted cheap
transportation to work and back. We bought them because they are as much works of art as they are
machines. We baby them, polish them and in most cases, we strive to customize them so they are unique to
us. Some expressions of customization come as light bars, LED lighting accents, radios, interphones and
other things that become a part of the bike's electrical system. Unfortunately, motorcycles are designed to a
very strict tolerance. It's a balancing act for the designers to make a package that looks good, falls within a
certain weight, produces a certain horse power and has all the bells and whistles that consumers want these
days. What that means is that the bikes we receive usually have very little extra capacity for additional
electrical loads. These are not big one-ton trucks with 20 pound alternators that have gobs of excess
capacity. So we have to be careful when making modifications or additions to the electrical loads on our
bikes.
5.2 Calculating the Total Electrical Load
To figure out the capacity of a bike's electrical system, you basically just have to determine what the output
of the alternator is and compare it to all the loads on the bike. However, it's never that easy. First, the output
changes as your speed (and therefore RPM) changes and the loads are not always constant.
Thankfully, someone has already gone to the effort of gathering the data for the ACE and he created a very
nice chart that shows it clearly. So all we have to do now is figure out how much of a load any new
accessories we add are and then see if the bike has the excess capacity to handle it. We also have to
examine the rpm/speed/gear ranges and determine a "profile" of our own riding technique to determine what
sort of average output we have during the conditions we do most of our riding.
So let's take an example...
After looking at the chart (shown at the end of this manual) and with my riding style, I can expect an
average output of 220 Watts. I choose conservatively here so that I don't over estimate and think I can
handle more power then I can. The ACE's Static loads (those loads that are constant and don't vary ) are 90
Watts. So that leaves us 130 Watts available to be used.
I want to add heated grips and a light bar to my ACE, so I find out what the draw is and add them up.
22 Watts = Heated Grips
80 Watts = Lightbar (40 Watts x 2)
========
102 Watts total
So we can safely add these accessories and still keep our battery charged. Just remember that at idle, as
mentioned before, we have a lot lower output and will actually be draining the battery, so it's a good idea not
to idle for long and/or reduce your load (switch off those Aux. Lights, for example)
Electrical Repair and Modification
Honda VT750CD ACE
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