Voltage Loss Across Running Light Circuit

[Harryc]

I installed a voltage meter (small Koso unit) on the Valk Tourer and wired it into the front running light circuit in the headlight bucket using the ground screw at the bottom of the bucket for ground. All connections are soldered. Prior to checking anything else I checked that the voltage displayed on my Fluke meter was exactly the same at the running light bullet connector in the headlight bucket and on the koso meter as displayed, so I know the koso meter is accurate. What I noticed right away when I turned the key on is the displayed voltage is low. It is also low while running the bike at speed. Key on about 11.5vDC, running about 12.8vDC. So I stuck my fluke meter on the battery. With the ignition off it reads 12.5vDC, and while running about 13.8vDC. Both of these voltages seem normal to me. My question is, where could I possibly be losing a 1vDC between the battery and the headlight bucket in the running light circuitry? I do have a run-turn-brake controller installed and it does have a load resistor hooked to it. I removed the load resistor, no difference. (I thought I had it there. ) The only other place I added resistors is in the indicator (turn signal) circuit because I installed LEDs for neutral, turn, and brights.  Ideas? I'm not going to tear the bike apart for this because I can just either add a volt while looking at the meter or run it directly to the battery, but if someone else has seen this maybe I can make the meter accurate with the right fix. Thanks!

[Challenger]

Your voltage loss is probably through the starter switch. On a STD and Tourer all the lights are powered through  that switch, I had a 1.75 voltage difference between my headlight and battery. Installed a smart switch by Bonz and now only show .25 voltage differential.

[Harryc]

Your voltage loss is probably through the starter switch. On a STD and Tourer all the lights are powered through the that switch, I had a 1.75 voltage difference between my headlight and battery. Installed a smart switch by Bonz and now only show .25 voltage differential.

I can check that with a meter I suppose, as long as there is an input and output access point, like a connector near the switch. I'll look into it, thanks. I don't guess installing a smart switch would have any impact on the running lights ... might be wrong. If that is the problem, I think a new starter switch would be the fix for running lights. At that point though 4 feet of wire to the battery is much cheaper.

[Valkpilot]

Check voltage between the positive connection to the volt meter and a different ground, either the main frame or a green wire in the wire loom, or direct to the battery negative terminal.

The bucket ground may not be reliable because its connection to the frame ground is through the head bearings.

I run a separate ground wire from battery (via auxiliary ground block) to the headlight bucket before relying on it.

Also, if you haven't already, your starter switch should be routed through a relay. 

http://www.valkyrieforum.com/bbs/index.php/topic,56705.msg546076.html#msg546076

[Harryc]

Check voltage between the positive connection to the volt meter and a different ground, either the main frame or a green wire in the wire loom, or direct to the battery negative terminal.

The bucket ground may not be reliable because its connection to the frame ground is through the head bearings.

I run a separate ground wire from battery (via auxiliary ground block) to the headlight bucket before relying on it.

Also, if you haven't already, your starter switch should be routed through a relay. 

http://www.valkyrieforum.com/bbs/index.php/topic,56705.msg546076.html#msg546076

Thanks, I'll look into all of this as well. Good stuff on the starter switch relay, I never ran into that one.

[Chrisj CMA]

Voltage on my batteries are just under 13V engine off.

Engine running is at or just over 14V.

I think the readings you reported are a bit low.

[indybobm]

Actually, the running lights are not powered through the starter switch. The voltage for the front running lights does go through the turn signal switch. in addition to the possibility of that switch reducing the voltage due to corrosion, there are many bullet connectors from the battery to the running lights. Each connector can add a small amount of voltage drop. Not too long ago, someone was losing 1 volt through the ignition switch. Lots of places to look.

[Harryc]

Actually, the running lights are not powered through the starter switch. The voltage for the front running lights does go through the turn signal switch. in addition to the possibility of that switch reducing the voltage due to corrosion, there are many bullet connectors from the battery to the running lights. Each connector can add a small amount of voltage drop. Not too long ago, someone was losing 1 volt through the ignition switch. Lots of places to look.

Interesting. What's the difference between the starter switch and the ignition switch?

[Harryc]

Voltage on my batteries are just under 13V engine off.

Engine running is at or just over 14V.

I think the readings you reported are a bit low.

You didn't read or understand my posts. At the battery and above idle I am seeing 13.8vDC . According to my manual (Honda Tech manual for the Tourer) that is within spec. I'd guess your system is overcharging and you're frying your battery. The spec from the manual is 13.2 to 13.8vDC regulated voltage.

[indybobm]

Actually, the running lights are not powered through the starter switch. The voltage for the front running lights does go through the turn signal switch. in addition to the possibility of that switch reducing the voltage due to corrosion, there are many bullet connectors from the battery to the running lights. Each connector can add a small amount of voltage drop. Not too long ago, someone was losing 1 volt through the ignition switch. Lots of places to look.

Interesting. What's the difference between the starter switch and the ignition switch?

What I meant is the starter switch is the push button on the right handlebar. The ignition switch is operated by the key.

[Valkpilot]

... and wired it into the front running light circuit in the headlight bucket using the ground screw at the bottom of the bucket for ground.

When you say "running light circuit" do you mean the lights in the turn signal housing?

Or, are you referring to aftermarket driving lights?

If you are referring to the running (AKA position) lights, that's problematic for a couple of reasons.  1) Power is disconnected from the running light on the side that the turn signal is flashing when you engage the turn signal switch.  2) The bulbs in the circuit act as resistors that could result in a voltage drop.

Standard/Tourer Position and Signal Circuits

Standard/Tourer Headlight and Horn Circuits

Your best bet for stability and accuracy with your volt meter is to come either directly off the battery or off an auxillary fuse block.  All the stock circuits have connectors and/or switches and/or bulbs that potentially interfere with your readings.

BonS created the Smart Switch to both protect the starter switch and deliver full voltage to the headlight for this reason.  Installing relays as suggested earlier also help with this, if you don't have a Smart Switch.

Interesting side note:  I installed a digital volt meter on my GL1800 Wing and tapped into the low-amp auxillary power circuit near the dash.   Two things happened.  If I used the power port that was daisy-chained in, there wasn't sufficient juice available to also power the voltage meter.  Second, when the wires heated up (Wings get hot under all that Tupperware) the increase in resistance on the wires caused the indicated voltage to drop as much as a volt.  I ran dedicated wires to the volt meter and fixed both issues.

[Gryphon Rider]

Voltage on my batteries are just under 13V engine off.

Engine running is at or just over 14V.

I think the readings you reported are a bit low.

You didn't read or understand my posts. At the battery and above idle I am seeing 13.8vDC . According to my manual (Honda Tech manual for the Tourer) that is within spec. I'd guess your system is overcharging and you're frying your battery. The spec from the manual is 13.2 to 13.8vDC regulated voltage.

14V from the alternator isn't going to fry the battery.

As indybobm said, power for running and turn signal lights does not go through the start button at the right hand grip.

It's not surprising that you're getting 1V lower at the headlight bucket than at the battery; Honda uses thin wiring to save weight and space.

[Harryc]

Thanks for the help guys. I think I am just going to go directly to the battery. It's just easier. .