Skytec HT wiring question

cjensen · #1 10-06-2008, 10:40 AM

I have the HT model starter for my O-360, and I'm a bit confused on the wiring for it. There are two model drawings to go off of from Skytec...

One is for "Experimental" applications with only a Master solenoid...

The other is for "Certified" applications with a Master and Starter solenoid, which is per Van's plans...

I'd like to use a push button start switch. It seems that with the master and starter solenoid, only a standard key switch should be used.

Can I use a push button switch with this starter and a master/starter solenoid combo?

uk_figs · #2 10-06-2008, 10:48 AM

I wired per the second diagram but I have the regular key switch from Van's, I do not see why you could not use a momentary push switch in it's place as long as you are using a master and starter solenoid configuration. The first drawing is only if you have a single master solenoid configuration.

scard · #3 10-06-2008, 10:53 AM

I wired like the second diagram and use a push button.

cjensen · #4 10-06-2008, 10:56 AM

Okay, sounds good...now for a stupid question as I'm still trying to learn all this wiring mumbo jumbo...

I have the copper bars between the starter and master solenoids installed...the drawings show a "bus" between the two with the starter switch wired to the bus. I'm assuming the bus and the copper bars are two different things? Again

...

gasman · #5 10-06-2008, 11:08 AM

I also wired mine like the second diagram. It is more of a standard way of doing it. And I used a push button also. The key switch is an item that can cause you many problems, like kickback and HOT MAG! Switches are better and so easy to install.

The top dwg can be used if you want to use the power lead from the starter back to the bus bar as a feed for your alternator load. BUT THEN YOU HAVE A BIG WIRE that is HOT all of the time the master is on..................... not good!

gasman · #6 10-06-2008, 11:15 AM

Quote:

Originally Posted by cjensen

Okay, sounds good...now for a stupid question as I'm still trying to learn all this wiring mumbo jumbo...

I have the copper bars between the starter and master solenoids installed...the drawings show a "bus" between the two with the starter switch wired to the bus. I'm assuming the bus and the copper bars are two different things? Again

...

The way it is in the sketch will work. But what it is showing is that the button needs power to close the starter sol.

You want to run a wire from your MAIN BUS FUSED, to the starter button, and then to the starter sol small stud.

rocketbob · #7 10-06-2008, 11:31 AM

Wiring per drawing 1 will give you the best performance. A small amount of resistance with the second contactor per dwg 2. can and will equate to a significant drop in starter performance.

rocketbob · #8 10-06-2008, 03:55 PM

A while back I did some experiments with trying to improve the mediocre performance of my LS series starter. If you ever go to a RV flyin, watch how many RV's have to "bump" the starter to get the prop over first compression. This doesn't happen with the new inline Skytec or the B&C, in my casual observation. Anyhow... got my trusty old Scopemeter out and did some experimenting. During cranking I have measured a 200mV drop across a NEW starter contactor where the inrush current was well over 300A. 0.2V may not sound like much but lets do a some math to put things into perspective as to why having two starter solenoids is really not a bright idea (no pun intended). Ohm's law is E=I*R (voltage=current*resistance), in this case since we know what E and I are we can solve for R. Now we have R=E/I so resistance in this case is R=0.2/300=0.00067. 0.00067 ohms at 300 amps doesn't sound like much but just follow me for a moment. Power (watts) is P=E^2/R so solving for power we have 0.2^2/0.00067=59.7. Lets just call it 60 watts. Having that additional contactor in there is the same as having a 60 watt bulb in series with your starter. Would you ever put a 60 watt light bulb in series with your starter?

vlittle · #9 02-17-2009, 03:35 PM

Foks, I've just reviewed Skytec's technical documentation and have emailed them questions.

Basically, I am trying to understand the risks of wiring up the Starter directly through a switch (or auto relay) rather than using a hand-grenade contactor.

My questions relate to G-performance and reliability of a direct connection (preventing stuck contacts). For example, they contradict Van's recommendations directly, and don't show an inverted contactor which I thought was better for higher positive G loadings.

The answers are mechanical, not electrical I'm sure. If the starter is immune from G loading, then wiring directly is simpler, lighter, cheaper and more reliable.

Vern

Mel · #10 02-17-2009, 03:55 PM

Quote:

Originally Posted by rocketbob

A while back I did some experiments with trying to improve the mediocre performance of my LS series starter.

Bob,
I think he is referring to the HT starter. They have much more power than the LS series. I've been running the HT for over 14 years on my -6 with 9.5:1 compression and it performs beautifully.
BTW, I used diagram 2 because I don't want a "big hot" lead up there all the time the master is on.