PLASMA II PLUS WIRING

My RV6 very slow build in New Zealand is almost ready for engine runs.

The engine is a Lycoming O-320-D1A, and I have replaced the RH Slick Magneto with a Light Speed Engineering Plasma II+ Electronic Ignition (EI) unit.

The wiring instructions state that the EI must be fed direct from the Battery (ie via its own CB), and the braided power wire must bridge the CB.

During wiring continuity & voltage checks I have discovered that this earthing arrangement results in me always having 12 V at the "upstream" terminal of the Master Switch, even with the EI CB is pulled, and the battery earthing strap disconnected.
I don't understand why this happens but can well imagine that it should not surprise me. The "continuous" braided earth wire seems to be the cause.

Proof of this is that if I disconnect the main earthing strap but leave the EI earth connected directly to the battery, and pull the EI CB, the 12V at the master switch remains.

On its own this seems a harmless arrangement, but it could be a trap for maintainers who wish to disconnect the battery as they would have to disconnect two wires to entirely disconnect the battery.

I have inquired with LSE re this matter, but they have not replied.

My question is what LSE mean by requiring the EI power to be earthed DIRECTLY to the battery. i.e. Can I ground this circuit at the firewall end of the earthing strap instead so that disconnecting this strap will always completely remove all power??

Sorry to bother you & I would be grateful for any feedback.
Maybe also my experience might be useful to others.

It would be very helpful if anybody with this system could do a voltage check at the Master switch input with all CB's pulled.

Or have I completely missed some more subtle cause?

Kind Regards.
Graham Murphy
New Zealand. (Winter is just starting here).

I got 1000 hrs on a Plasma II + on one side of a O320D2J . My interpretation of that was run an isolated ( single sourced) power ( 12vDC) directly off the battery or in my case comes off the lug on the battery side of the starter solenoid ( or could be battery side of master solenoid). It is shielded 18 guage single conductor power wire. That routes thru firewall and over to a CB Specifically for the Plasma Ignition. That " pull off " CB is located adjacent to the mag switch and labeled " Plasma II + IGN Aways HOT" Left position. it stays Pushed In ( all time ) and the ground for that side "Mag" is wired out of the DB connected on the Plasma unit to the Bendix mag switch. The ground ie shield was treated as any other ground. Don't remember where its terminated at the source end ,but would be fine to run it all way back to a common firewall ground which is connecting the Battery side ground cable. Kinda where the power wire originated there on lower firewall. The other end of the shield goes to GRND on my mag switch.

I believe the intent from LS is to have Always HOT ( 12vDC ) on the Plasma unit all all times. ie conventional MAG grounding is done thru the Plasma II+ box.

Sounds like you may have power source wired as " Only hot when the master is hot"

All above is FYI, yours may be wired differently.

Graham said:

My RV6 very slow build in New Zealand is almost ready for engine runs.

The engine is a Lycoming O-320-D1A, and I have replaced the RH Slick Magneto with a Light Speed Engineering Plasma II+ Electronic Ignition (EI) unit.

The wiring instructions state that the EI must be fed direct from the Battery (ie via its own CB), and the braided power wire must bridge the CB.

During wiring continuity & voltage checks I have discovered that this earthing arrangement results in me always having 12 V at the "upstream" terminal of the Master Switch, even with the EI CB is pulled, and the battery earthing strap disconnected.
I don't understand why this happens but can well imagine that it should not surprise me. The "continuous" braided earth wire seems to be the cause.

Proof of this is that if I disconnect the main earthing strap but leave the EI earth connected directly to the battery, and pull the EI CB, the 12V at the master switch remains.

On its own this seems a harmless arrangement, but it could be a trap for maintainers who wish to disconnect the battery as they would have to disconnect two wires to entirely disconnect the battery.

I have inquired with LSE re this matter, but they have not replied.

My question is what LSE mean by requiring the EI power to be earthed DIRECTLY to the battery. i.e. Can I ground this circuit at the firewall end of the earthing strap instead so that disconnecting this strap will always completely remove all power??

Sorry to bother you & I would be grateful for any feedback.
Maybe also my experience might be useful to others.

It would be very helpful if anybody with this system could do a voltage check at the Master switch input with all CB's pulled.

Or have I completely missed some more subtle cause?

Kind Regards.
Graham Murphy
New Zealand. (Winter is just starting here).

Click to expand...

That is because the master switch is a grounding switch and still has a path back to the battery through the ground in the EI box still connected to the battery. All connections to the ground (earth) lug on the the battery must be removed if you want to isolate the battery.

DennisRhodes said:

I got 1000 hrs on a Plasma II + on one side of a O320D2J . My interpretation of that was run an isolated ( single sourced) power ( 12vDC) directly off the battery or in my case comes off the lug on the battery side of the starter solenoid ( or could be battery side of master solenoid). It is shielded 18 guage single conductor power wire. That routes thru firewall and over to a CB Specifically for the Plasma Ignition. That " pull off " CB is located adjacent to the mag switch and labeled " Plasma II + IGN Aways HOT" Left position. it stays Pushed In ( all time ) and the ground for that side "Mag" is wired out of the DB connected on the Plasma unit to the Bendix mag switch. The ground ie shield was treated as any other ground. Don't remember where its terminated at the source end ,but would be fine to run it all way back to a common firewall ground which is connecting the Battery side ground cable. Kinda where the power wire originated there on lower firewall. The other end of the shield goes to GRND on my mag switch.

I believe the intent from LS is to have Always HOT ( 12vDC ) on the Plasma unit all all times. ie conventional MAG grounding is done thru the Plasma II+ box.

Sounds like you may have power source wired as " Only hot when the master is hot"

All above is FYI, yours may be wired differently.

Click to expand...

You may want to reconsider this location for an uninterrupted power source for your EI.
Looks like you may have power source wired as " Only hot when the master is hot" also.

gasman said:

You may want to reconsider this location for an uninterrupted power source for your EI.
Looks like you may have power source wired as " Only hot when the master is hot" also.

Click to expand...

Plasma IS hot off battery ALWAYS. NO WAY is it powered off a master buss that can be turned off! It is connected on the LUG of the starter solenoid that is hard wired to battery positive same as the lug on the master solenoid. The pull off CB is the ONLY way you can kill power on the Plasma for N908DR.

The Vans suggested wiring shows a single battery cable attached to a copper lug which terminates to both the starter AND master solenoids. Ie battery connection.

DennisRhodes said:

Plasma IS hot off battery ALWAYS. NO WAY is it powered off a master buss that can be turned off! It is connected on the LUG of the starter solenoid that is hard wired to battery positive same as the lug on the master solenoid. The pull off CB is the ONLY way you can kill power on the Plasma for N908DR.

The Vans suggested wiring shows a single battery cable attached to a copper lug which terminates to both the starter AND master solenoids. Ie battery connection.

Click to expand...

Would you post the Van's drawing that shows this connection.