Negative Ground for a Single Device

I have a dilemma, I would like to run a modern device on my Norton, but at this point in time I really don't want to convert the whole bike to negative ground. Is there a device or a way around this issue, or is converting the whole bike over the only way to go?

I had a old mini that was + earth and when installing a new stero that was - earth I had to insulate it and wire it directly to the battery, so maybe will have to do the same thing on the Norton.

You can do it with a relay, and as Ashman says by isolating it from chassis + ground. I'm considering putting a very small electronic tach on my Norton, but will probably make a mount out of 1/4" black plexiglas sheet to isolate it. Not elegant, but I know I can make it work.

maaseyracer said:

I have a dilemma, I would like to run a modern device on my Norton, but at this point in time I really don't want to convert the whole bike to negative ground. Is there a device or a way around this issue, or is converting the whole bike over the only way to go?

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More info would help. If the device has only two wires and does not require a ground via whatever mounts it, then there's no issue.

Certain items as Greg implies, will be more difficult. I'd like to a brake light flasher and/or a turn signal cancelling flasher unit, but all products I have looked into are negative ground only. The flasher lights and brake lights on our bikes use only a single power wire, and ground out via direct mounting points to the frame or ancillaries. Would need to operate on the lamps to insulate from frame grounding and fit a new wire to the lamps to connect to battery negative, then switch the incoming power lead to be fed from the brake flasher or turn light flash canceller unit output wire.

Bit tricky to figure out but could be done if the desire is great enough.

I'm not a sparky nor know what your device is but you can't wire it back-to-front? - i.e. +ve terminal to earth (maybe through switch) and -ve to "power" (brown?)
I've done that on my ES2

maaseyracer said:

a modern device

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Is the type of device a secret?

Unless this modern device is grounded through its case it does not care if the vehicle is -ve or +ve earth. Red wire goes to +ve black to -ve and the rest you need to work out from the wiring diagram but again as long as its not grounded it does not care.

maaseyracer said:

I have a dilemma, I would like to run a modern device on my Norton, but at this point in time I really don't want to convert the whole bike to negative ground. Is there a device or a way around this issue, or is converting the whole bike over the only way to go?

Click to expand...

Massey,
I run 2 wires connected directly to the battery (negative ground)with an SAE plug that I use for my electric vest and GPS going up to the handlebars.Its there if I need it and has been working fine.
Mike

Tornado said:

Certain items as Greg implies, will be more difficult. I'd like to a brake light flasher and/or a turn signal cancelling flasher unit, but all products I have looked into are negative ground only. The flasher lights and brake lights on our bikes use only a single power wire, and ground out via direct mounting points to the frame or ancillaries. Would need to operate on the lamps to insulate from frame grounding and fit a new wire to the lamps to connect to battery negative, then switch the incoming power lead to be fed from the brake flasher or turn light flash canceller unit output wire.

Bit tricky to figure out but could be done if the desire is great enough.

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Tornado,
I use a flasher that is also a self canceling unit from MotoGadget(M-stop) which they said would not work however I just reversed the polarity on the advice from another guy on the forum and has been working fine for quite some time.Another plus is that it is very small.
Mike

YING said:

Tornado,
I use a flasher that is also a self canceling unit from MotoGadget(M-stop) which they said would not work however I just reversed the polarity on the advice from another guy on the forum and has been working fine for quite some time.Another plus is that it is very small.
Mike

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Interesting. I bought a cheapo brake flasher unit, with one wire in, one out, to fit inline to a brake with a positive power feed. Figured it should work if I just flipped its connections around so that the black wire went to the brake switch and red to the light, but alas it did not work. Perhaps the voltage drop on the red wire coming from frame ground, through light (led in my case) to unit was not tolerated?

Tornado said:

Interesting. I bought a cheapo brake flasher unit, with one wire in, one out, to fit inline to a brake with a positive power feed. Figured it should work if I just flipped its connections around so that the black wire went to the brake switch and red to the light, but alas it did not work. Perhaps the voltage drop on the red wire coming from frame ground, through light (led in my case) to unit was not tolerated?

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If wired normally, your brake switch has a white and a brown wire. White is hot (negative) and brown goes to the brake light bulb. The other side of the bulb goes to red (ground).

On a Norton, the frame is not a reliable ground - red wires are the ground (if still positive ground).

A LED taillight would require a 2-wire LED-ready flasher to do what you want (assuming you want your brake light to flash when engaged).

marshg246 said:

If wired normally, your brake switch has a white and a brown wire. White is hot (negative) and brown goes to the brake light bulb. The other side of the bulb goes to red (ground).

On a Norton, the frame is not a reliable ground - red wires are the ground (if still positive ground).

A LED taillight would require a 2-wire LED-ready flasher to do what you want (assuming you want your brake light to flash when engaged).

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The turn signal lamps do use the frame, via the headlamp ears and license plate bracket & mudguard, to reach earth...not a direct wire. But I agree the brake & tail lamp does get a direct wire to earth.
Brake light flashers are not just standard turn signal flashers...they have a short period of flashing then go steady on until brake is off/on cycled. The one I fit on my modern Bonneville, a Kisan "Tail Blazer" unit, uses a decaying rate (fast to slow) of flash for a few seconds before going steady on.

Tornado said:

The turn signal lamps do use the frame, via the headlamp ears and license plate bracket & mudguard, to reach earth...not a direct wire. But I agree the brake & tail lamp does get a direct wire to earth.
Brake light flashers are not just standard turn signal flashers...they have a short period of flashing then go steady on until brake is off/on cycled. The one I fit on my modern Bonneville, a Kisan "Tail Blazer" unit, uses a decaying rate of flash for a few seconds before going steady on.

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There is a red wire in the headlight with a crappy connector to the headlight shell. That is where the ground for the turn signals comes from in standard wiring. That also makes all the frame somewhat a ground but grounding through headstock bearings and the clutch cable is not something I would call reliable.

I add a ground to both front and rear turn signals so I can be sure I have a reliable ground when I wire bikes. Also, I have a reliable ground to the tail and brake lights.

I know the brake light flashers are no standard flashers - that's why I said "assuming you want your brake light to flash when engaged".

What you describe is very simple electronics, but not with two wires if you need to be isolated from a positive ground system, it would require three wires and most likely re-wiring of the brake and tail lights depending on where the device provides power or ground to it.

Better is that there are inexpensive 4-wire LED brake flashers that can easily be wired to a positive ground system as the input power and output are isolated.

marshg246 said:

More info would help. If the device has only two wires and does not require a ground via whatever mounts it, then there's no issue.

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Masseyracer,
If it is something like this,I added a quad lock charging device to charge phone ,two wires, installed as per instructions keeping wires isolated from the frame but added a fuse into the -ve wire of the quadlock ,along with the already included fuse in the +ve wire .
No issues works well ,
Cheers Hendo

A 1961 Aston Martin that I occasionally work on is Positive earth, but it has a CD player fitted that is negative earth. I fitted a perspex mounting box so that the CD unit is completely isolated from the chassis and ran the wires to the appropriate polarity feed. It has worked fine for over twenty years.