[badlag86]

So I confirmed some of my fears tonight while trying to install a normal h4 hi/lo HID kit. I had some suspicion that it wouldn't work. Low and behold, it didn't. Here's why.

Most motorcycles of decent size (over 300cc) run their headlights on a 12VDC system. What I mean by this is that the lights get their power DIRECTLY from the battery and the electricity only travels in one direction; from battery to light to ground.

Most smaller bikes (such as the Grom) run their lighting on an AC system. This means that the direction of the electricity alternates from one way to the other creating temporary lulls, and peaks, in power.

Looking at the wiring diagram made me think otherwise, since the power wire feeding the headlight comes from the regulator/rectifier. I assumed it would be a DC circuit. After busting out my handy-dandy-multimeter and a direct voltage adapter (DVA) or PVA (also known as 'peak voltage adapter' for measuring peak AC voltage) and a few quick tests later I came to realize that both the High and Low beams operate on AC current. Not only is it AC current, but it peaks around 30VAC.

The HID kit comes with a relay setup and connects directly to the battery for the main power source. The big problem lies in the fact that the lulls in AC power cause the relay to open the circuit, causing the HID bulb to flicker (which is damaging to both the relay AND the bulb).

Currently I'm figuring a work-around that will still allow me to use the stock hi/lo switch and make the lights functional. My biggest concern right now is figuring out how much I'll end up cutting into the wiring harness/soldering back together to make it happen. I'm thinking it may be as simple as hard-wiring the switch to the battery (instead of the regulator/rectifier) and putting in a secondary ground-control switch to be able to turn the lights off when I turn the bike off.

I know a few of you have found ways to make it work, but I get the feeling you may be using a different kit than myself. Any better ideas out there?

 

[The_Outrider]

I'm a little surprised by this, the Grom stator looks huge compared to the Wave/Nice...which are about double the size of the old Z50 setup. I had guessed that the Grom was fitted with a 100-150W alternator. EFI needs a lot of current to operate. Apparently, it takes even more than expected. Honda fitted the old Z50 (and 72c variants that were based on it) with a "balanced" elelctrical system, that feeds half of alternator output to the headlight, directly as AC and the other half to a half-wave rectifier, which leaves a feeble 25% of alternator output as DC...barely enough to charge the battery, on those models.

Since this setup was used as a cheap workaround for a inadequate alternator output, it's only logical think that it may be on the Grom for the same reason. If so, converting to a total full-wave DC system may prove difficult for most. It may not even be viable. Assuming that you possess the electrical knowledge, keep an eye on system output. If it cannot keep up, you may end up dead on the road...when voltage drops below fuel pump & ECU requirements.

 

[LateNA]

First, are you using a motorcycle specific HID harness such as the Morimoto Motocycle harness? It connects directly to the battery and then to a frame ground. It does have an input for the stock H4 connector, but I believe this is just to control hi/low beam. This is all theory as I do not have my HID headlight in just yet, it is in transit.

 

[Fat Grom]

I went with the DDM 15K kit, but I'm only running Low beam no high Beam. Reason for not running high beam, too lazy didn't want to mess with the same problem you are having. Solution: I'll wire it one of these rainy days when I'm less lazy!


Sent from my iPhone using HondaGrom.net

 

[badlag86]

I'm a little surprised by this, the Grom stator looks huge compared to the Wave/Nice...which are about double the size of the old Z50 setup. I had guessed that the Grom was fitted with a 100-150W alternator. EFI needs a lot of current to operate. Apparently, it takes even more than expected. Honda fitted the old Z50 (and 72c variants that were based on it) with a "balanced" elelctrical system, that feeds half of alternator output to the headlight, directly as AC and the other half to a half-wave rectifier, which leaves a feeble 25% of alternator output as DC...barely enough to charge the battery, on those models.

Since this setup was used as a cheap workaround for a inadequate alternator output, it's only logical think that it may be on the Grom for the same reason. If so, converting to a total full-wave DC system may prove difficult for most. It may not even be viable. Assuming that you possess the electrical knowledge, keep an eye on system output. If it cannot keep up, you may end up dead on the road...when voltage drops below fuel pump & ECU requirements.

I don't see any reason why the stock alternator couldn't keep up with the demands of FI and HID's. Although, putting a full-wave system in would be ideal since you'd really only have to change out the alternator and regulator/rectifier. The question is whether or not you can find a regulator/rectifier that is built to output the correct voltages for this system. I haven't the electrical prowess to create one of my own, so I'll probably shy away from that until someone else does it for me. lol.

 

[badlag86]

First, are you using a motorcycle specific HID harness such as the Morimoto Motocycle harness? It connects directly to the battery and then to a frame ground. It does have an input for the stock H4 connector, but I believe this is just to control hi/low beam. This is all theory as I do not have my HID headlight in just yet, it is in transit.

Correct. I am using a motorcycle specific HID harness. It works exactly as you describe, but since the stock H4 connector controls a relay inside the bulb housing for hi/lo, it just sits there and vibrates the whole time the bike is running.* Low doesn't work at all and High will flicker on/off. I'm contemplating wiring the yellow wire going into the hi/lo switch to the tail lights, which run off 12VDC and turn on when the bike turns on. As long as I start the bike right away, I don't think it'll affect amperage to my starter motor too greatly.

*edit* the power going to the stock headlight harness from the switch is AC voltage. Causing the relay to vibrate very quickly because of the constant on/off/on/off/on/off effect of AC.

 

[badlag86]

I went with the DDM 15K kit, but I'm only running Low beam no high Beam. Reason for not running high beam, too lazy didn't want to mess with the same problem you are having. Solution: I'll wire it one of these rainy days when I'm less lazy!


Sent from my iPhone using HondaGrom.net

I'll have to look into how that kit is wired so I might be able to copy it somehow. Either that or cut it up, solder everything back together in a giant mess of speaker-wire and heat-shrink tubing, and call it a franken-bike... lol (j/k)

 

[Fat Grom]

I'll have to look into how that kit is wired so I might be able to copy it somehow. Either that or cut it up, solder everything back together in a giant mess of speaker-wire and heat-shrink tubing, and call it a franken-bike... lol (j/k)

Mine isn't flickering at all BTW.


Sent from my iPhone using HondaGrom.net

 

[Eurobeaner]

instead of using the signal for the relay as the headlights, tap into the front signal (running light) or rear tail light. those 2 should be dc and constant

 

[Marcuscc]

I had the Hi/ low setup originally and don't know how it ever worked plugging it in normally because of the AC system. But the high beam ended up being useless because it wouldn't function once the bike was moving anyways. Something went wrong with that system and I just wired it to my ignition key that gives off a straight 12v from the battery once the key is in the ON position and connected the ground straight to my battery. Have been running it like this in my bike for almost a month now with no issues

 

[LateNA]

I am using the H1 bulb with a mechanical cutoff to activate the high beam, so we will see if it works or not.

 

[The_Outrider]

Short of adding an ammeter, the only way know for sure if the charging circuit output is keeping up with the demands of your HID ballast is to see if the battery ultimately discharges over time. Electric start requires a lot of battery capacity and quick recharging, to work reliably. Perhaps the charging circuit has enough untapped "safety margin" to handle an HID. It's also possible to run at a partial loss and that could take hours before the battery is discharged.

 

[gromjohn]

instead of using the signal for the relay as the headlights, tap into the front signal (running light) or rear tail light. those 2 should be dc and constant

The front signal is constant until you use the turn signal. It turns off when turn signal is applied then goes back to constant 12v.

 

[Nerfkhat]

i have hid setup on my bike. I noticed as well that hid wouldnt work if i tapped into the h4 bulb socket. So i rewired it with a relay and used the signal for high beam to turn on the hid's. Which uses a direct battery source for the ballast. Works fine for me. But i will eventually pickup the TRS motorcycle relays so i can take advantage of my bi-xenon projector. I used high beam because i have a halo angel eye i use as my DRL.

 

[badlag86]

So I solved my HID problem... using the following method. I realized that the relay that determines hi/lo was powered by the actual hi/lo switch, which derives it's power from the alternator. In order to feed it direct current, I de-pinned the yellow wire (power in) going into the hi/lo switch and wired it directly to the tail light power wire. This has made my lights fully functional in the easiest way possible (meaning the least amount of cutting and soldering). Also the least amount of alteration to the wiring harness. I did not have to modify the HID kit at all for this. My high and low beams function as intended. The only downside is that the lights come on as soon as I turn on the key. I'm ok with this.

Thought I'd let y'all know. If anyone would like a make-shift wiring diagram, I'll be more than happy to draw one up and send it to you.

 

[LateNA]

Badlag, if you don't mind, I would appreciate this wiring diagram. Since I am using an H1 bulb and a projector that moves a flap to create a high beam, I am not sure if I will have an issue until I get the setup in hand and see how it works. I will have it Monday but have a feeling I may need to do that mod you did.

 

[badlag86]

Badlag, if you don't mind, I would appreciate this wiring diagram. Since I am using an H1 bulb and a projector that moves a flap to create a high beam, I am not sure if I will have an issue until I get the setup in hand and see how it works. I will have it Monday but have a feeling I may need to do that mod you did.

Give me a day or two to get it drawn up. I haven't got anything to draw on around me, but I'll grab my notepad from work tomorrow and try to post tomorrow night.

 

[badlag86]

forget that last post. I found a piece of paper, lol. It's a pretty basic diagram, but since I don't have any pencils in my house, I decided to keep it simple.

 

[LateNA]

You the man!

 

[LateNA]

So today I hooked everything up as per badlags instructions and I am still getting strobing from the headlight. I thought it was my grounds so I tried a different one and got the same outcome. Anyone have any ideas?