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LettersFromFlyoverCountry 03-08-2011 04:19 PM

Toggle switch - ignition wiring
All of the plans I've seen for the RV electrical systems involve the keyed ignition switch and, of course, two mags.

I'm not doing things that way. I'm using regular old toggle switches -- one for the left mag, and one for Lightspeed and I'd like to find a schematic somewhere (Aerolectric Connection has one but it involves a double throw switch) that shows exactly how these should be wired.

I really don't want to screw this part up.

Any help would be appreciated.

DakotaHawk 03-08-2011 04:31 PM

What's the purpose?

What do you want your ignition switches to do?

For example, if you want to use simple single pole single throw SPST toggle switches, then just route 14V+ through one switch to the LS ignition, and route ground through the other switch.

On the other hand, if you want to make sure that the engine will only start with just the LSE, then you need to have DPST switches to get the logic worked out. My LSE/Mag is set up with the DPST switches. The starter contactor will only engage if the LSE is ON and the Mag is OFF.

hobby_rv6 03-08-2011 04:56 PM

You are doing exactly what I did. I used three NO-NC toggle switches in a row, just to the right of my keyed master switch (which is only an off/on switch). The toggle switch closest to the master switch is the alternator field switch, next is the p lead on the magneto and the last one is for the 12v lead to the electronic ignition controller module (I used an Electroair unit).
Lastly, I used a momentary push button switch to engage the starter solenoid. My original design used the button type switch with a ring around it to protect against an inadvertent push, but I didn't like the way that it looked. I ended up with a switch like this

This momentary switch is a "security" kind normally used on vending machines which mounts flush with the surface and cannot be accidentally bumped. I found it at a local electric supply shop for about $5.


LettersFromFlyoverCountry 03-08-2011 08:22 PM

Basically, I want to see a schematic so I can understand the principles of how they work and how the switching is best accomplished between the mag and the EI. BTW, didn't I read something somewhere that the engine is best started on the mag and the EI is brought online after engine start?

szicree 03-08-2011 08:42 PM

I had one mag and a lightspeed wired with toggles. The diagram is in something called Express PCB (I think). I'd be happy to email you a copy of my diagram, but I think you'll need the software to view it. It was a free download though.

RV10Rob 03-08-2011 08:50 PM

Start on the EI
One of the benefits of the EI is easy starts. I know some people with a mag + lightspeed start on the mag only, but I have no idea why. I have a Plasma III and impulse coupled mag, so I start on both.

As for the wiring, for the mag, you attach one end of the switch to the p-lead and the other end of the switch to ground. For the mag, the switch is mounted "upside down"; that is, when the switch is "up" it's actually open, which for most things would mean off. When the mag is "off" (disabled), the switch is closed, which grounds the p-lead.

The Light Speed is straightforward. One end goes to the lightspeed power (connected directly to your battery) and the other end to the controller box. The Light Speed installation manual shows this, too.


DakotaHawk 03-08-2011 08:59 PM


Here's a quick and dirty diagram.

If your mag is impulse coupled, then you can start on either the LSE, the Mag, or both.

If your mag is not impulse coupled, then you must have the mag off to start.

Starts are always easier on the LSE because of the hotter spark that is optimized by the LSE circuitry for best start.

vmirv8bldr 03-08-2011 09:20 PM

Bob, that depends on your mag and whether or not it is impulse coupled. Most people prefer to start on the EI. It fires a hotter spark for a longer duration which will aid in starting. I will attempt to upload a pic of the wiring schematic I made. It is based off of 'lectric Bob's schematic where the starter can only be engaged when the EI is on and the Mag is Off.

(EDIT: I corrected the drawing to show the correct switch)

N427EF 03-08-2011 11:19 PM

Follow LSE diagram.
Follow the lightspeed diagram precisely and nothing else.
The diagram is on LSE's website and it should be in your documentation.
Klaus is very specific about using the shield (ground) all the way to the battery ground and 12V directly to the battery terminal with a PCB in between.
As has been pointed out upside down for the mag switch, this is especially important when you use anti rotation keyed switches plus all the other reasons mentioned.
Most people who use an LSE use a mag with impulse coupling in wich case
you can start on both, or LSE only, or mag only.
I see no reason why you would want a mag without the impulse coupling
and an LSE ignition.

LettersFromFlyoverCountry 03-09-2011 07:00 AM

Bill Pendergrass sent me just what I was looking for:

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