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Relay for starter (Button on Tostens stick)

Big NO.I doubt that's rated for the amps. Get a dedicated starter contactor designed for that duty. You the contact circuit will be switched on the hot side versus ground side for fail-safe mode so four terminal, etc. Check Vans, ACS, auto parts store, whatever. Save money on something expensive.
 
No reason why you can’t use your PH relay to drive the starter relay (switching a ground contractor to a positive output).
 
A big maybe

The stock starter contractor draws 3.5 amps. The manual says only the circuit that can handle 5 amps is the Flap circuit because of the board trace size. The trim motors draw little current. Better ask PH.
 
Use an automotive relay to keep current low at the tiny stick grip switch. Ground the relay coil through the switch, and use the 30 & 87 terminals to control the start contactor.
 
Sounded like he was asking for the relay side of the device. If not, would you want serial devices between the start button and the contact coil? He'll probably already need serial devices on the power side of the start button. Hopefully a start enable would be a must-have for a stick mounted start button. Ground-to-energize makes this more important from a fail-safe standpoint. Why overcomplicate it further?

There are many relays besides the legacy silver cans that can handle the start conditions and draw milli-amps on the contact side (GigaVac for one). Again, spend a little extra and don't overcomplicate it. IMO.
 
Yep - first RV project started off life with the start button on the stick. The stick button provided a ground path for the standard 12vdc, 30 amp contact relay (it drew 100ma to hold close). That relay provided power to the firewall mounted solenoid that provided power to the starter. It all worked just fine - and the location of the stick button was such that it was way too easy for it to be pressed when you did not want it to be pressed (as in engine running). After ~20 hours this feature was removed and a standard start button installed on the side panel (RV-8A).

I never put the start button on the stick again.

Carl
 
Add a starter disconnect switch to panel.

Carl Froehlich said:
Yep - first RV project started off life with the start button on the stick. The stick button provided a ground path for the standard 12vdc, 30 amp contact relay (it drew 100ma to hold close). That relay provided power to the firewall mounted solenoid that provided power to the starter. It all worked just fine - and the location of the stick button was such that it was way too easy for it to be pressed when you did not want it to be pressed (as in engine running). After ~20 hours this feature was removed and a standard start button installed on the side panel (RV-8A).

I never put the start button on the stick again.

Carl
Click to expand...

Works well, also if using VPX their start circuit will not let the starter engage while seeing RPM's over 500.
 

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Surprising Philosophy

I'm a little surprised two people have mentioned switching/control on the ground circuit on the starter relay. I had assumed (incorrectly?) the other way was better.

For bus isolation, relay (contact side) control on the ground makes sense; no related circuit protection, very short/no wire runs.

- FMEA open circuit -> no difference/advantage between hot side control.
- FMEA short circuit -> bus isolation lost but it is still fail-op/ bus isn't (uncommanded) taken off-line; typically a lessor effects multiplier of the matrix.

For engine starter control, the aforementioned makes less sense to me.

- FMEA open circuit -> same as above
- FMEA short circuit -> depending on where short is: loss of switch safety to inadvertent starter engagement.

Having an uncommanded starter engage can be dangerous if the engine is not running. Having it engage while it is running is expensive at the least.

From this, contact control should be via the hot side. Am I seeing it wrong or not the whole picture?

If this is an old dead horse topic, my apologies. Intelligent responses/reasoning would be appreciated. "xxx hours so far. No problems" responses won't be helpful. This is one of those "fine until it suddenly isn't scenarios."

Anyone?
 
You don’t have to run the starter wires on the Tosten grip through the PH relay. In fact I wouldn’t given the potential current draw. Since my flaps were wired differently I had Tosten wire my momentary flap switch with three wires for flap circuit completion. This way my stick flap switch (which is only on the pilot’s grip) doesn’t go through the PH relay and still allows the panel flap switch to work independently. Just a thought!

I had to send one grip back to Tosten for him to rewire the momentary switch for this configuration but Kevin was happy to accommodate it for minimal cost.
 
Last edited:
Xkuzme1 said:
I’m assuming that I’ll also need a relay for the starter?
Click to expand...

I have my starter button on an Infinity grip and like it there. I'm also using a PH 3-channel UTRB. I had to use an additional (small) 12V relay to switch from pos to neg (or vice versa) for the starter contactor so that eliminated the concern of the PH relay being up to the task.

It's been awhile and I can't remember the details at the moment but the current coming out of the Infinity grip/PH-UTRB is the opposite of what I needed. As I recall, it was positive and the starter contactor needed negative. So, adding the additional relay was a no brainer.

I cannot speak to how the Tostens grip function. Hopefully all that doesn't confuse things.
 
The relay between the Infinity Grip and the firewall mounted start solenoid is needed as the switch on the stick is not rated for the firewall mounted solenoid current draw.

Carl
 
Infinity States Relay not Req.

Carl Froehlich said:
The relay between the Infinity Grip and the firewall mounted start solenoid is needed as the switch on the stick is not rated for the firewall mounted solenoid current draw.

Carl
Click to expand...

The Infinity grip order form states that a relay is not required if using the NO button for start. Switch is rated 6A @ 12V.
Question: is that acceptable, or is a relay a better option?
 
This is a topic that many people have opinions against adding a starter button to the stick. I wired mine to allow it for now. Some people have also added an additional switch as an enable which is only turned on during starting so that accidental touching of the stick starter button can be effectively ignored.

I used an automotive relay as Dan suggested. I used a TE PN: 3-1393303-4 relay with an 1N4007 protection diode. This relay seems like a reliable selection from my investigation.
 
Start on stick has been a happy thing for 1150 hours now. That said, note the arm switch and flashing LED to indicate the start system is armed.

I can't bring myself to starting a light tailwheel airplane without the stick being full back. Probably not an issue with the -8, but knowing for sure could be expensive.
.
 

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I did something similar. I’m sure it is configuration and pilot specific but I have never inadvertently hit the button and love being able to hold the stick on startup. I can’t hold the stick back with my knees like in a Citabria.
 
andoman said:
The Infinity grip order form states that a relay is not required if using the NO button for start. Switch is rated 6A @ 12V.
Question: is that acceptable, or is a relay a better option?
Click to expand...

Perhaps that 6A switch would work, but for me that is cutting it too close to load draw. I’d use a relay.

Carl
 
Tinker,
Mine is an automotive Start Solenoid. A Cole Herse( I would have to dig to find a part number). It is hot all the time and needs a ground to engage the relay. The button on my infinity grip is used to create the ground to the relay. I have a guarded safety switch between my start button and the relay for protection. My Rocket is almost 10 years old. No issues.
Ryan
 
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