Headlight wiring/relays

[Guest rotorhead]

I think this topic may have been addressed before but I thought this might help as well. I have rewired the healight in an effort to bypass the switch at the handlebar and also increased the wire size to allow a better current flow. I actually got these instructions from a chap on the msg board over at Moto Guzzi groups on Yahoo. He was willing to distribute freely so I thought I would pass it on......it works quite well

 

Hopefully the schematic will load here....if not and there is someone out there that knows how to post it better than me, I will email to you and you can post it for me if you would. I'll give it a shot but don't know if I can make it work.

 

This is an attempt to make the conversion from stock headlight wiring to a much more efficient direct battery feed simple. The headlight on my Motto Guzzi EV (with all of its 7 connectors and finally what looked like a 16 gauge wiring, from connector to headlight) was not real bright. After talking to several Guzzi riders and Mike @ MPH (you should get to know him) I decided to change from stock wiring to a direct feed, using 12-gauge wiring and 2 heavy-duty headlight relays. Bear in mind there are different schools of thought on this. There is a suggestion that 14-gauge wiring from the battery to the headlight relays for both ground and power is a good way to go. I used 12-gauge I thought it would be best to give the electrons almost unrestricted paths. I soldered in the fuse holder. I don’t like crimp connectors but was forced to use crimp type spade lugs. I mounted everything in the headlight can. I had an old neoprene-kayaking glove lying around (I never throw anything away, drives the wife nuts) and pushed everything in there to keep it insulated and keep it from vibrating. After about an hours work I was finished. I took it for a ride and WOW!!

 

I noticed a great improvement in the headlight brightness. I should add that I don’t like to cut any stock wiring and I didn’t. I used male spade lugs and pushed them into the old headlight plug then bought a new plug from O’ Reilly auto parts and connected that to the relays. This way if something should go wrong I could always disconnect the relays and plug the headlight back into the old headlight plug, I like redundancy I used to ride Harleys.

 

Be aware since the headlight is substantially brighter aiming it is critical. Follow this link http://www.webmaster10.com/ldr/headlight_aiming.html and you’ll find a simple method of headlight aiming

 

Well good luck.

 

List of Materials:

 

2 Heavy-duty headlight relays, from Car Quest

1 Replacement H4 headlight plug (I had to show the O’Reilly salesman a new bulb, which matched my old one, so he knew what I needed).

8 insulated female spade lugs

3 male spade lugs

1 insulated in line fuse holder

6 feet of 12-guage wire, red

6 feet of 12-gauge wire, black

2 ring connectors (for connecting to the battery)

2 ft of tubing (I like to make my wiring nice and neat)

 

 

I modified this alittle and used velco to secure the relays to the back of the bucket. Relays were purchased at autozone for about 4 bucks each (2 required). I also wired directly from btry. using an inline fuse and splice into existing wires where neccessary.

[Guest rotorhead]

YIKES.............It post alright!! Apologies for the size of the thing

[al_roethlisberger]

Excellent

 

 

Mike Haven at MPH was supposed to also be working on a similar plug-and-play kit for this. I don't know if they've finally got the product/kit ready

 

al

[dlaing]

This also eliminates the excessive load on the starter relay on the earlier bikes!

[Guest Marcel]

And for the metric types amongst us :

 

what is 12-gauge wire and what is 14-gauge wire? It's probably to do with the amount of copper per foot but just like to make sure ....

[Guest rotorhead]

12 gauge is heavier (larger diameter) than 14 gauge. Much of the wire on the bike now is either 14 or 16 gauge. Twelve gauge is quite heavy and is probably overkill....I dunno the direct correlation to metric though.

 

Take a look at this and see if it helps

 

http://www.reade.com/Conversion/wire_gauge.html

[Guest Marcel]

Right, so 12 gauge is equivalent to 2 mm2 wire.

 

That is heavy indeed for bike wiring as we use 10 gauge (2,5 mm2) for wiring 16 amps on 230v in house.

[docc]

 

Lookherefor more on this topic of rewiring the headlamps.

[Guest Bruce]

12 AWG wire is .087 inches in diameter or 2.2 mm

14 AWG wire is .070 " " " 1.7mm

16 .055 1.4 mm

 

These are approximate # as there are different ways of making it.

 

If I remember my High School Physics

 

Wattage = Current times the voltage

 

so a 60W bulb in a 12V system will draw 5amps of current, a 100W bulb would draw 8.33 amps.

 

Power lost in the system is Current squared times the total resistance

 

Therefore even though the resistance is a small number, it gets multiplied by 25 in the first example and 69.4 in the second example.

 

Resistance is dependant on the material ( all the same here ), heat, cross sectional area, and the length of the wire used. The smaller the AWG the bigger the diameter, the lower the resistance.

 

Total resistance would also have to include 'contact' losses through relay contacts and various connectors.

 

So, to reduce the total resistance eliminate contacts, use a larger diameter wire, reduce the run length, and keep the wires as cool as possible.

 

 

Based on what I've seen there are more contacts than needed and individual wire lengths are often 3 to 4 times longer than needed. This is because MG, like everyone else, buys wiring harnesses which are designed to strap on to the frame and plug in various componets as quickly as possible. Ultimately this works out to cheaper. Wire is cheap, labor is expensive.

 

Next winter I am planning to greatly simplify and beef up my head light circuitry and isolate it from the starter control circuitry. Less contacts, larger wire, shorter wiring runs.

 

If, as reported, the head light is noticably brighter I would suspect the contacts as the primary source of excess resistance. Its excess contact resistance that spoils the fun in the starter circuitry. With over 30 years of experience with electrical things gone wrong, the number 1 cause of the trouble is the contacts.