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Infinity grip switch driving S702 starter relay

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recapen(at)earthlink.net
Guest

Posted: Tue Mar 03, 2015 5:09 am Post subject: Infinity grip switch driving S702 starter relay

Anyone else using an Infinity grip switch to actuate a S702 starter relay?



According to the specs of the Infinity grip switches, the contacts are rated at 6Amp.

 	  Quote: 	
		  From the B and C site, the S702 has a 2.5Ohm coil - so the math at 14volts works out 

to 5.6Amps...and that would be a max since the battery would provide less at cranking 
	


time.



The numbers say it should be OK - I'm looking to find out if anyone is doing it for 

real - and how is it working for you?



Thanks,

Ralph Capen

rnewman(at)tcwtech.com
Guest

Posted: Tue Mar 03, 2015 5:32 am Post subject: Infinity grip switch driving S702 starter relay

Ralph.  I would recommend you look at our Smartstart module for doing this function if you want to use the stick grip switch to drive the start contactor.    The switches used in the stick grip may be rated at 6 amps, but that would be for a resistive load.   The start contactor is an inductive load and has a significantly different effect in switches than a pure resistor.  

Additionally, our module has a built in one minute timer and an interlock feature, making the stick grip starting concept safer and more useful.  



All the info is at www.tcwtech.com 

Bob Newman

TCW Technologies, LLC

610-928-3420



 	  Quote: 	
		   On Mar 3, 2015, at 8:07 AM, Ralph E. Capen <recapen(at)earthlink.net> wrote:

 

 

 

 

 Anyone else using an Infinity grip switch to actuate a S702 starter relay?

 

 According to the specs of the Infinity grip switches, the contacts are rated at 6Amp.

> From the B and C site, the S702 has a 2.5Ohm coil - so the math at 14volts works out

 to 5.6Amps...and that would be a max since the battery would provide less at cranking 

 time.

 

 The numbers say it should be OK - I'm looking to find out if anyone is doing it for 

 real - and how is it working for you?

 

 Thanks,

 Ralph Capen

recapen(at)earthlink.net
Guest

Posted: Tue Mar 03, 2015 5:50 am Post subject: Infinity grip switch driving S702 starter relay

Interesting - I'll look in to this....

How many are out there interfacing the Infinity grip switch to the Starter relay?



Still want to hear if anyone is using my stated configuration though....



Thanks





--

flying-nut(at)cfl.rr.com
Guest

Posted: Tue Mar 03, 2015 6:21 am Post subject: Infinity grip switch driving S702 starter relay

Ralph, you may find some folks that are using the infinity switch direct 

for the starter contactor but our fleet is relatively young.  Problems 

won't surface 'till down the road a ways.  My start switch is is on the 

key so I didn't have your same situation. However, it's far better to 

wire in a relay now than later, IMHO.



My question is why put the starter on the grip anyway?  You only use it 

once each flight and typically don't need to have your hand on the grip 

at that time.  Plus, what keeps you from accidentally hitting that 

switch while you're in the air???

Linn



On 3/3/2015 8:48 AM, Ralph E. Capen wrote:

[quote] 

 Interesting - I'll look in to this....

 How many are out there interfacing the Infinity grip switch to the Starter relay?



 Still want to hear if anyone is using my stated configuration though....



 Thanks





 --

recapen(at)EARTHLINK.NET
Guest

Posted: Tue Mar 03, 2015 6:40 am Post subject: Infinity grip switch driving S702 starter relay

Linn,



Good points made!



I currently have it on a relay that the hand-grip activates with a safety interlock 

switch - my line of thinking is to simplify by removing the relay and driving it direct.



My initial line of thinking for putting it on the hand-grip was for an in-flight restart -  

which would require one hand on the stick while the other works throttle and mixture.



What I currently have works very well - but it is complex and I am trying to simplify...

Looking for evidence of the problem you alluded to.



Thanks,

Ralph

--

dmaib@me.com

Joined: 25 Apr 2006
Posts: 454
Location: New Smyrna Beach, Florida

Posted: Tue Mar 03, 2015 6:53 am Post subject: Re: Infinity grip switch driving S702 starter relay

I agree with Linn and others concerning the need for a relay. I wish I had used one of my Infinity Grip buttons for starting. I do want to hold the stick when starting, and I find that for activating my start button, manipulating mixture and throttle, and holding the stick, I am short one hand. (especially starting when the engine is hot) In my case, the VP-200 would take care of the issue of activating the starter when you don't want it activated. Otherwise, I would use Bob's TcwTech start protection switch.

_________________
David Maib
RV-10 #40559
New Smyrna Beach, FL

carl.froehlich(at)verizon
Guest

Posted: Tue Mar 03, 2015 6:55 am Post subject: Infinity grip switch driving S702 starter relay

Ralph,



On the RV-8A the first version had the bottom push button on the stick being

the start button, providing power to the starter solenoid.  This button does

not have the capacity to operate the starter solenoid directly.  I installed

a small 12VDC relay (100ma coil, ~$1.50 from Allied Electronics) in the

circuit such that the stick button operated the relay, the relay then

provided power to the starter solenoid.



But - this setup was quickly changed as twice during the first flights I

inadvertently bumped the stick start button while the engine was running.  I

kept the relay set up and just added a small momentary pushbutton out of the

way at the top of the right side switch/breaker panel to use instead of the

stick button.  



On the RV-10 I just used the standard 10amp panel pushbutton for engine

start to directly provide power to the starter solenoid.



Bottom line - recommend not using the stick buttons to operate the starter

solenoid.



Carl



--

recapen(at)earthlink.net
Guest

Posted: Tue Mar 03, 2015 7:16 am Post subject: Infinity grip switch driving S702 starter relay

Carl,



Thanks for your input.



I have a secondary safety switch to prevent the accidental activation along 

with the relay like you described currently installed.

My intent was to simplify by removing the relay.  Sounds like my best bet 

is to leave it as is!  It works great for me.....



Ralph





--

recapen(at)earthlink.net
Guest

Posted: Tue Mar 03, 2015 7:17 am Post subject: Infinity grip switch driving S702 starter relay

David,



Thanks for the info.  I'll probably leave mine as is since the relay and safety switch work well!



Ralph





--

flying-nut(at)cfl.rr.com
Guest

Posted: Tue Mar 03, 2015 9:52 am Post subject: Infinity grip switch driving S702 starter relay

Ah, it seems the answer is ...... "If it ain't broke, don't fix it!!!"



Linn ..... couldn't resist

do not archive



On 3/3/2015 10:16 AM, Ralph E. Capen wrote:

[quote] 

 David,



 Thanks for the info.  I'll probably leave mine as is since the relay and safety switch work well!



 Ralph





 --

Tim Olson

Joined: 25 Jan 2007
Posts: 2871

Posted: Tue Mar 03, 2015 11:16 am Post subject: Infinity grip switch driving S702 starter relay

This post since it was cross posted, may not have gotten

the same follow-up on all lists, but I'll add my reply

to another poster's comment on prop windmilling being

enough in-flight...



---



I know in my case I've done complete mixture cut-off tests

in the plane where I've stopped the engine completely,

and also flown it dry on tanks for testing, and the prop

keeps spinning so fast that you may even perceive that

the engine is still making power.  You just feel the loss

of thrust.  So unless you happen to pull the nose up and

near-stall the plane, I doubt the starter will ever need to

be cranked to re-start.  For me, as soon as the fuel

supply was there again, it roared back to life.

Also, the start operation isn't *that* complicated.

I understand the want to have a hand on the stick

and one on the throttle/mixture, but my knees do a fine

job of holding the stick for a normal start.

Additionally, if the plane is in trim, I don't see

the worry about holding the stick with a hand

while doing that once-in-a-hundred-years in-flight

restart that you may do.  The knees would do ok

there too, but in actuality, you're not going to be

manipulating the mixture and throttle much if you're

doing an in-flight start.  It's not like you'll be

doing a hot-start procedure at 7,000'.



Tim

recapen(at)earthlink.net
Guest

Posted: Tue Mar 03, 2015 11:34 am Post subject: Infinity grip switch driving S702 starter relay

Agreed!





--

vanremog(at)aol.com
Guest

Posted: Tue Mar 03, 2015 7:03 pm Post subject: Infinity grip switch driving S702 starter relay

It may also be an AC rating.  DC is significantly harder on contacts during switching.  The combination of DC switching and collapsing flux field from a large inductive would be death fro the switch.  In DC applications always ensure that you have a back biased catch diode installed across an inductive load or the back EMF can take out the switching component in short order.

   

  -GV

   

   

  --

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