Electrical Circuits

[Peteg]

I recently  installed a flat 4 trailer light whip on my 26 year old incandescent standard. My bike is close to stock, but it still seemed like it was time to checkout circuit loading. I decided to make this post as it could be helpful to someone. The following documents my readings:
Brake / Turn Signal / Horn (10 amps) – Non stock adds : Trunk – 2 brake lights, USB outlet, Self cancelling turn signals. Full load draw - 9.5 amps total, 3 brake lights - 5 amps, signal lights - 2 amps, horn - 2 amps, usb & scs - 0 amps, usb 1 phone on charge - 0.5 amps. Trunk brake lights removed during flat 4 installation and added to trailer module output for reduced circuit load and trailer logic conversion.
Head light (10 amps) – halogen head lamp total draw - 4.6 amps, 4 amps low, 0.6 amps high.
Headlamp VTX 1300 – after market Eagle LED, 2.0 amps total, 1.6 amp low, 0.4 amps high.
Running and gauge lights (10 amps) – Non stock adds: Trunk four running lights, 2 led hard bag lights. Full load draw 6 amps.
Accessory (5 amps) – No load. Added flat 4 power module with 2 trunk brake lights and led trailer lights. Total load - 3.8 amps, trunk brake lights - 3.5 amps, led trailer lights - 0.3 amps.
All readings were taken with the circuit fuse removed and replaced with a multi-meter, in-line set on the 10 amp dc scale.
I love the way Honda wired these bikes.  The use of bullet connectors at the main harness connections,  that are compatible with standard red crimp-on bullet connectors, makes it easy to make significant modifications without cutting bike wires. If a future owner doesn’t want the changes, they can easily be unplugged.
Also per readings on my bike, Honda left significant excess power on most circuits; often more than the 5 amp accessory circuit. Certainly anyone who has upgraded to led lights has more than 5 amps of excess power available on the 10 amp lighting circuits. The key is to take 15 minutes and see where your at, and how much load your adding, to avoid overloading circuits.
Hope this is helpful.

[John Schmidt]

Keep in mind, standard non-metric bullet connectors aren't the same size as metrics although can be forced into place. Metrics are available from a number of suppliers and it's a good idea to keep a good supply on hand, as well as a collection of the various size multipin connectors.

[Peteg]

Thanks John. From experience I'm confident what I did will be reliable, but it definitely would be more professional if I had the right connectors. Another unprofessional thing I did was the flat 4 wiring harness I made to run from the new controller under the truck to the main harness next to the fuse box. I didn't have any multi-conductor wire I trusted for my new 7 conductor harness so I used the 16 ga trailer wires that came with my trailer wiring kits. Just wrapped them with Scotch 33 and hid them under the seats.  I also pulled the right trunk  lamp module and cut the right brake light wire so I could feed it through a new bullet connect from the output of the trailer light control module.

So can you give me a good source for 1. the single wire male female crimp on connectors  2. the 3 pin connectors at the rear trunk lights and other multi-pin connectors  3. sheathed multi conductor stranded wire that won't fatigue at the connectors, I guess like 20 ga?

[ridingron]

... The key is to take 15 minutes and see where your at, and how much load your adding, to avoid overloading circuits. ...

Thanks for your efforts in figuring all the loads out. I seriously doubt many guys here could do that or take the 15 minutes to see where they are at (electrically speaking) on that circuit.

[John Schmidt]

So can you give me a good source for 1. the single wire male female crimp on connectors  2. the 3 pin connectors at the rear trunk lights and other multi-pin connectors  3. sheathed multi conductor stranded wire that won't fatigue at the connectors, I guess like 20 ga?

Vintageconnections.com is one of the best out there for vintage bikes. Their products and kits cover most every bike model from the mid-60's on up. If you're looking for sealed/waterproof connectors, just google  it and you'll find all you need. I keep a good collection of all types...just in case. 

[Avanti]

Also look here.
http://www.cycleterminal.com/index.html

[Peteg]

Thanks, I'll record those sites in the electrical section of my shop manual.

[Itinifni]

A good general rule when adding accessories is fuse for 2x the expected load and wire for 2x the fuse.

[Pluggy]

Here's a short helpful explanation.  This one mentions selecting a fuse 1.1 to 1.5x greater than the maximum expected load.

https://www.oznium.com/blog/how-to-determine-the-fuse-wire-size-for-your-project/

Electronic items, like audio gear, typically provide the fuse in the power wire.  If you can't determine if there is a fuse, contact the manufacturer of the item for a recommendation.  A fuse will protect the bike wiring, but we don't want the electronics to be the fuse.

[Jess from VA]

I use fused or circuit breaker powerstrips on all electronics, many of which also have their own in-line fuse.

We used to get frequent short brown outs, which played hell on electronics.   

[cheeseman1969]

Just to add on. I am rewiring right now for the connectors going to the rear. I have a standard bike but the previous own put on a trailer plug that worked well and no issues. But now I got a interstate trunk so redoing it all. I am using https://www.jrdtools.com/  connectors. Work really really well so far. Get the crimp tool to. Makes it easier. NOTE: This is Chinese/Taiwan company but saw on two different youtube revival car shows of the host using it. So figured to try it out.
 Also, make sure that you have good wiring diagrams. Helps alot to match up.