100W at 12V is around 8.3A. I like around a 30% margin for safety and variance of the element making the draw, so let's call it 10.8A. For continuous power transmission (ie: headlight type draw), you need an 11AWG conductor for 12A, 12AWG for 9.3A.

I don't know what wire gauge is used on the headlight harness for the TW, but I'm pretty sure it's closer to 17AWG'ish giving you a whopping 2.9A or 34.8W worth of capability.

If you plan on running higher current lighting like that, you should run an appropriate gauge wire through a fused link straight from the battery, and use the stock 12V feeds to main/high beam to toggle relays that switch the line from the battery. That will give you OEM functionality without melting your wiring and leaving you in the dark or pulled over by the local constabulary.

Next thing to consider is how much power the generator setup on the bike can supply reliably. I'd be surprised if it put out 50W-75W total (I really have no idea, just guessing at this one), meaning you're going to end up with a dead battery and possibly blown generator after your riding time exceeds the capacity of your battery. Unless of course you run a big battery, take very short rides, and stick it on a charger between rides.

In short, it's probably a bad idea. As mentioned, LED is the way to go for more light output on meager wattage. There are several options for that.


Edit: Are you sure stock is a 55/60W? I seem to recall reading here on the forum that stock light is about 30W-35W.

 

Going to 100 watts may fry your wiring.

 

I have been using this for three years now. Not sure how the fan will do with mud I ride mostly street https://www.cyclegear.com/parts/sp...ed-conversion-kit?gclid=EAIaIQobChMIgMuMv5Ow2gIVUzuBCh1BtgQhEAQYASABEgLl0fD_BwE


Sent from my iPhone using Tapatalk

 

I have also been using this for a few years also and ride home from work at night just about every day. One of the best things I have changed after my seat concepts seat....

 

LED is the best choice.

 

18 gauge, for short distances, will handle 10 amps
16 gauge...12 amps
14 gauge...15 amps

See chart for higher amperage: Ampacity Charts

For most primary wiring, automotive or motorcycle, I use 16 gauge (or larger) for physical strength.

Stock wiring for a 100 watt high beam may be OK, but I know of several H-D riders who have melted the 1/4" blade connector to the H4.

I am a big fan of LED: My truck has been converted for dome, cargo and high brake lights. Both travel trailers 100% converted (to run longer on a solar charged battery).

LED has an initial purchase expense, but has much longer life, more vibration resistance, and uses much less electricity.

 

I was going by this chart: https://www.powerstream.com/Wire_Size.htm

I do recall when I had the front bits off taking measurements for CAD that the wiring seemed a bit on the light side. I tend to err on the side of bigger is better. Maybe it's leftover trauma from my days playing with BL cars. All hail Lucas, prince of darkness.

I searched this site when I was planning my lighting upgrades, and could swear I found a post claiming that the stock wiring wasn't good for more than 35W or so, but I can't seem to find it again. The light going on mine is pretty low draw anyway at 3A high/1.5A low (TL 27270C).

Even still, I'd be wary of trying to run 100W worth of light on this thing. Does anyone know how much power the stock generator can put out?

 

The earlier TW from 88 to 2000 ran a 30/35 – from 2000 on, it went up to 55/60

If you wire it up post battery, the only complications are how long you use it for, and as has been mentioned, the wiring

So the only things to watch out for are the wiring melting, and boiling the battery dry

“Some of us” have questioned this before, mostly on heated grips etc – but it’s the same thing – however, no-one has admitted to detailed results yet. All we get is “I’ve used this for years”, without any considered damage reports

The problem with reporting is likely to do with “variables” – how long did you use the high beam for, how long did you use heated grips for etc – you get the idea …….

 

The Mr.Gizmo TW came with an upgraded Hella H4 bulb that was much brighter than the stock H4. I will report back if I can find any wattage identification. I never had any discharge issues with it using stock incandescent bulbs everywhere else and a lead acid battery. It is available to a good home since I have subsequently replaced it with a LED H4 I like better.

 

Great info. I can only imagine how dark it was for pre-2000 bikes, the stock bulb in my `09 was barely adequate for around town. I currently have an LED drop-in from yonder bike shop (better but kinda blue'ish with an iffy pattern), but looking forward to getting some proper light thrown out of the front. I'm (half) mirroring the lighting setup I have on 3 of the cars with a 7" high/low LED main, and 4" aux/fog LED covered in yellow Lamin-X.

 

I have the H4 LED from superbrightleds and love it. They thought out some things that a lot of others have not. One it has no fan or the big dangly heatsink strips. It also was easy to install and retains the factory rubber boot to keep crap out of your housing. Best part for me was the beam pattern is very close both high and low beam to the stock halogen, keeps that wide pattern with a pretty sharp cutoff on low, and pretty much floods the area with light on high beam. It uses multiple rows of tiny LEDs in roughly the same positions as the halogen filaments and even has that reflector cup under the low beam LEDs like a halogen H4 has under the low beam filament. There is a darker spot here and there but hardly noticeable for the most part. Less than 20 watts and brighter than the stock bulb. Was around $40 or so when I got mine last year.
https://www.superbrightleds.com/mor...adlight-bulb-conversion-kit-with-compact-heat-sink/3930/8566/#tab/Photos&Videos

As a side note I had a Cyclops LED bulb before and the beam pattern was the same round spot both high and low, it just got brighter.

Oh, and another detail. End of summer last year I was riding in traffic on 100 degree days commuting with the SBLED bulb. Was worried that the fact they went with just a heatsink with no fan might be a problem. Still works just fine.

 

I have the H4 LED from superbrightleds and love it. They thought out some things that a lot of others have not. One it has no fan or the big dangly heatsink strips. It also was easy to install and retains the factory rubber boot to keep crap out of your housing. Best part for me was the beam pattern is very close both high and low beam to the stock halogen, keeps that wide pattern with a pretty sharp cutoff on low, and pretty much floods the area with light on high beam. It uses multiple rows of tiny LEDs in roughly the same positions as the halogen filaments and even has that reflector cup under the low beam LEDs like a halogen H4 has under the low beam filament. There is a darker spot here and there but hardly noticeable for the most part. Less than 20 watts and brighter than the stock bulb. Was around $40 or so when I got mine last year.
https://www.superbrightleds.com/mor...adlight-bulb-conversion-kit-with-compact-heat-sink/3930/8566/#tab/Photos&Videos

Lots of good items at superbrightleds.com
I need to check bucket space on my CB1100, although I seldom ride at night.

 

Installed an LED headllght on my TW and so far, so good.

I installed a 38,000 lumen LED H4 headlight on my 2014 TW yesterday. The light is white instead of yellow and i’m pretty sure I will be able to see better and my battery will hold up longer. It was a tight squeeze and I had to make a back cover out of duct tape and electrical tape. The manufacturer is Cyron, the part number is ABH4-C6K. I bought it from J&P Cycles for my Dyna Low Rider, but it did not fit (no room inside the headlight bezel and no hole in back to route the active cooling system). I will let you know how it holds up.

 

i'll also endorse the H4 fanless LED headlight bulbs from superbrightleds.com, i copied twbigblake's dual headlight / grom mod and am running two of the H4-HLV4-M bulbs on a splitter from the usual headlight, no amperage issues, and yeah, they are super bright.

also worth mentioning these bulbs come w/ a lifetime warranty, i recently had one go bad after an ill-considered water crossing - blame the chintzy headlight enclosure not the bulb here, everything inside the enclosure was soaked - and superbrightleds issued the full value of the purchase as store credit so i could pick a new one, as the models had changed slightly since my purchase. great when a product is good and the vendor that sells it is also legit.