Alternator output question

[goldminerusa]

On an 82 1100s, will the electrical system handle 2, 55 watt fog lights connected to the Acc. fuse? And what is the alternator output at idle and at redline?

[virgilmobile]

No.It will discharge the battery,and blow the 5 amp fuse.
5 amp X 13.8 volts = 69 watts.
2 @ 55 watt lamps = 110 watts.
They would require a # 12 wire and a 15 amp circuit on a separate switch.
Here's a general idea.
The bike was designed with enough stator capability to operate the bike and charge the battery with little left over.
On a good day,my 1100 draws 10.5 amp at 13.8 volts running at 2000 rpm,and after recharging the battery for 10 minutes at 14 amp ,it tapers off to 4 amp draw.
So with it going good and at 3500 rpm I have a whopping excess of maybe 100 watts left to play with.
You let it lollygag under 1800 rpm and it will barely keep the battery from discharging.

So if you want to add 2@ 55 watt driving lights,your gonna have to get the power from somewhere else.
First thing may be convert everything except the headlight to LED and use 35 watt lamps instead of 55 watters.
The best I've measured from a gl1100 stock stator is right at 24 amp 14.6 volts maxed out 3500 rpm.

[goldminerusa]

Yes. But, the copy of the honda service manual i have indicates a 10A fuse in the ACC location, as does the fuse box label. 10A x 13.8v = 138w, 28 watts remaining, unless we all have different versions of Mr Honda`s manual. What about the engine 15A fuse? Does the engine really need 15A to run the ignition? Yes, i know "maybe 100 watts left over". This begs the question, is there a way to upgrade the ALT. without chopping up my bike for the "poorboy conversion"?

[virgilmobile]

There are differences.My acc is a 5 amp.It all boils down to available excess power at a given rpm.
The fuse for the bike is rated at 15 amp.The bike will draw 10-12 amp normally,so it's fused at 125%.

Remember,the actual specs say the system can provide 300 watts at 5000 rpm.
You will get lower as the rpm drops and I'm sure you don't run the bike up there continuously anyways.

The stator really doesn't start to put out any excess until it hits 1800 rpm,it's output is directly proportional to the rpm.

There is,I heard,of a aftermarket stator that is made to provide up to 350 watts of power under the same conditions
The drawback is the cost plus pulling the engine to replace it.We usually just live with the fact and compensate to be able to add more lights.

[WingAdmin]

First thing may be convert everything except the headlight to LED and use 35 watt lamps instead of 55 watters.

That's exactly what I did on my 1100, and I ran it that way for many years with no problems. I did however put a relay in, hooked to the neutral switch, so that whenever the bike was in neutral, it turned off the 35 watt lights. That way, when the bike was sitting idling (meaning it already wasn't putting out enough power to run everything) it didn't have the additional load of 70 watts of lights.

[goldminerusa]

I see, and thanks to both of you. Wingadmin, do/did you feel that 70 watts of fog light is sufficient to provide a meaningful difference? And will you expand on how you wired the relay?

[goldminerusa]

Oh, and i`ve read recently that converting to LED bulbs requires changes other than simply changing bulbs, can either of you expand or correct me/us on that?

[WingAdmin]

Oh, and i`ve read recently that converting to LED bulbs requires changes other than simply changing bulbs, can either of you expand or correct me/us on that?

You will also need to change your flash relay to an electronic flasher. There are no other changes required.

[GL1800&GL1100]

...... I did however put a relay in, hooked to the neutral switch, so that whenever the bike was in neutral, it turned off the 35 watt lights. That way, when the bike was sitting idling (meaning it already wasn't putting out enough power to run everything) it didn't have the additional load of 70 watts of lights.

Hi, I've fitted two additionsl hi/low headlights to my 1981 GL1100, originally through a kill switch and a couple of relays. Then I came across your idea of hooking up to the neutral switch, although I actually tapped into the neutral light's lg/r wire. In doing so what I didn't realise is that the lg/r wire. What I've now learned is that the lg/r wire is in fact a ground because the neutral light grounds via through the neutral switch. Consequently, by splicing into the lg/r to trigger a relay the neutral light now grounds through the relay so when the bike's in gear the neutral light stays on, although very dimly. I'm therefore wondering how you got around this.

[Rambozo]

You need to measure to see if the relay coil is backfeeding the light. A properly placed diode should take care of the dim lamp glow with an incandescent bulb. If you have a neutral LED, more isolation might be required. LEDs glow with the slightest leakage current. Change your relay to a DPDT so you can use the extra contacts to isolate the neutral led.

After re-reading your post I'm not sure how you have your relay wired. I don't have a 1100 diagram so I can't id the lg/r wire. Since the neutral light is switched ground, your relay also needs to be switched ground.

[GL1800&GL1100]

You need to measure to see if the relay coil is backfeeding the light. A properly placed diode should take care of the dim lamp glow with an incandescent bulb. If you have a neutral LED, more isolation might be required. LEDs glow with the slightest leakage current. Change your relay to a DPDT so you can use the extra contacts to isolate the neutral led.

After re-reading your post I'm not sure how you have your relay wired. I don't have a 1100 diagram so I can't id the lg/r wire. Since the neutral light is switched ground, your relay also needs to be switched ground.

Thank you. All of my bulbs are original, no leds. After some late night studying of the wiring diagram: The instrument warning lights share the same 12v feed via one of the 5amp fuses, to light they ground through there respective destination switches. In other words, the reverse of a normal wiring configuration where the 12v feed to the respective light is switched, not the ground side. The neutral light grounds through the neutral switch. Therefore, having spliced the lg/r ground side of the neutral light (which goes to the neutral switch) to create a relay trigger, when a gear is selected the neutral light now grounds through the trigger output of the relay, albeit it's a very weak ground so it lights very dimly. So there actually isn't a back leak from the relay to the neutral light, which might otherwise be resolved by a diode. I've looked at a DPDT but as the issue is the neutral light grounding through the relay a DPDT won't resolve it. I just can't fathom what WingAdmin could have done. But thanks again.

[Rambozo]

I can think of several ways to fix it. But I don't have any good way to draw a diagram that I can post here.
Where are the two coil wires from your relay going to?
What I meant by using a DPDT relay is to have the neutral switch only operate the relay, not the lamp. Then switch the lamp with the extra set of contacts. This would provide complete isolation. However, I doubt that is even necessary if you wire the relay coil to both sides of the neutral lamp. The relay will only energize when the lamp is on and there won't be any voltage differential to make the lamp glow when the neutral switch is off.

[Rambozo]

Not pretty but it should be postable.

[GL1800&GL1100]

Not pretty but it should be postable.
PXL_20230420_081745574.jpg

Got it! A picture speaks a thousand words. My cul-de-sac was being stuck on grounding the trigger side of the relay independently, but if wired like your diagram it'll ground through the neutral switch and share the neutral light grounding.
64 and still lots to learn.
Thanks again.

[WingAdmin]

Correct. And the +12V for the relay doesn't have to come from the positive side of the light. Use +12V from anywhere (on only when the bike is switched on, obviously) through the relay coil, then use the neutral wire for its ground.

[Rambozo]

If you pull the coil positive from another source, there could be a slight difference between the two positives and that could cause a dim glow, especially with an LED. That is what I thought he was describing at first, and why I said adding a diode could help. Not likely, but something to keep in mind.

[Rednaxs60]

A consideration is the impact on the electrical system operation. Max stator output is at ~5500 RPM, sliding scale as RPM is reduced. If you use these new lights at low RPM and have other electrical additions, have a good battery installed because the battery is used to supplement the electrical system requirement when the stator output is insufficient for the load. A used, degrading, faulty battery can cause you a lot of grief if things start going "south", reminiscent of the days of "generators". Good luck.

[GL1800&GL1100]

Correct. And the +12V for the relay doesn't have to come from the positive side of the light. Use +12V from anywhere (on only when the bike is switched on, obviously) through the relay coil, then use the neutral wire for its ground.

Thank you both Rambozo and WingAdmin. I did use the pos side (wire Bk/Br) of the neutral light but I can see now that that wasn't actually necessary, but it's tidy all the same as I needed to access the Lg/R wire (to the neutral switch) for the ground which is located in the spagetti behind the steering counter weight. I complicated things further because I also wanted a master on/off switch to kill the 2 additional headlights during periods of prolonged low revs, e.g. crawling in town/city. This master switch triggers a SPST relay (1) which accepts a 10amp fused supple from the battery and forwards it to pin 30 on a *SPDT relay (2), which is triggered by (turned off) the neutral switch, so when in gear relay 2 forwards the 10 amp supply to pin 30 on a second SPDT relay (3), which is triggered by the bike's high beam, so pin 87A supplies the two additional low beams and pin 87 (when switched) the two additional high beams.

*For relay 2 (the neutral switch relay) I used a spare SPDT relay and blanked of pin 87, so when in gear the relay is closed and the lights work off pin 87A, but when neutral is selected the 10amps is thrown to pin 87 which is blanked off and the lights turn off. I could have bought a "normally closed" SPST relay but I'm tight and impatient!

Thanks again. You've been a terrific help.

[GL1800&GL1100]

No.It will discharge the battery,and blow the 5 amp fuse.
5 amp X 13.8 volts = 69 watts.
2 @ 55 watt lamps = 110 watts.
They would require a # 12 wire and a 15 amp circuit on a separate switch.
Here's a general idea.
The bike was designed with enough stator capability to operate the bike and charge the battery with little left over.
On a good day,my 1100 draws 10.5 amp at 13.8 volts running at 2000 rpm,and after recharging the battery for 10 minutes at 14 amp ,it tapers off to 4 amp draw.
So with it going good and at 3500 rpm I have a whopping excess of maybe 100 watts left to play with.
You let it lollygag under 1800 rpm and it will barely keep the battery from discharging.

So if you want to add 2@ 55 watt driving lights,your gonna have to get the power from somewhere else.
First thing may be convert everything except the headlight to LED and use 35 watt lamps instead of 55 watters.
The best I've measured from a gl1100 stock stator is right at 24 amp 14.6 volts maxed out 3500 rpm.

I appreciate that this is an old thread but I've added two bullet hi/low headlights to my '81 GL1100, given that the OEM headlight is not much better than a candle, and I came across this thread.

You'll see from my other posts that I've been reconfiguring the wiring installation given the experience I've had using the lights. They came with 55w/60w H4 bulbs which the bike couldn't handle on anything other than motorway (UK) speeds, so >5000rpm. On variable open road speeds 3000-4500rpm the voltmeter managed to hold its own flutuating between 12v and 13v depending the rpm. But at prolonged <3000rpm speeds, such is in town/city, the battery would discharge. I therefore added a switch for such circumstances but have now followed WingAdmin's hack of introducing an auto-cut off when neutral is engaged.

All that said, since the bike coped well with the additional 2 x 55w/60w load at >5000rpm, but only just at around +/- 3500rpm, I checked the manual which says the max output is 0.3kw @ 5000rpm, whereas you found the max output was at 3500rpm.

Anyway, I'm going to step down to 35w/35w because (i) most of my riding is at <5000rpm speeds, (ii) I dont like the idea of putting the strain on the old girl who's made it this far, and (iii) whilst replacing the alternator on my GL1800 wasn't a big deal, having to open up the rear of the GL1100 to replace the stator is not a job I want to be the cause of.