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Author Topic: Are Push Button Starter Switches Any Good?  (Read 5328 times)
boogiethecat
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« Reply #15 on: April 03, 2007, 10:20:16 PM »

Jerry, sorry to pop your bubble but in this particular case, and regarding ANYTHING with a coil, diodes ARE very important.  Vibrators went out in the 50's although I'd ask you to think about WHY they may have had longer point life (is that any different than a switch?) or less radio noise with diodes... gee, exactly the reason I was talking about!  You need to do some studying and get yourself into the modern world... at least please don't tell people here to forget things that you obviously don't understand.  That kind of misinformation is not healthy.  And FWIW these days almost all cube relays have built in diodes or MOV devices... why? because they protect that which is energizing them.

Ok, someone else can have the soapbox now.  Smiley

G
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Dave Siegel
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« Reply #16 on: April 04, 2007, 04:59:01 AM »

OK guys, be nice now. Boggiethecat is probably very right, the problem is I don't understand a word he said. That's my problem. Electricity. I have a handle on 120 but 12 volt stuff can be very confusing for me. So here we go again.

I have determined from all your posts that I have wired my ignition switch incorrectly. (Understand that our bus sat in a field for 10 or 12 years wide open, there, the furry birds with no wings scratched and ate at every piece of wiring in the entire coach. I spent months removing every inch of wiring and replacing it as I needed it.) There are 2 8D batteries that supply power to the dash where I have a momentary on rocker switch that goes back through the rear electrical panel box and then on to supply power to the starter selenoid. N0 relay. Not bypassed, no relay. I guess that's where I went wrong. Now I want to fix it.

I understand about the little cubed relay and it sounds cheaper than the Ford firewall style starter relay. But wouldn't I be better off to #1 replace the starter switch with a heavy duty ignition switch and then #2  add a Ford style relay to feed the starter selenoid? I guess I would place the Ford style relay in the rear electrical panel box and then #4 run heavier wire to the starter selenoid from there?

Thanks for all your suggestions.

Dave Siegel
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JackConrad
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« Reply #17 on: April 04, 2007, 05:28:06 AM »

Dave,
   I agree with BoogieThe Cat. You definately need something to prevent ALL the current from going through your start switch. Although a "cube" relay would probably work and they are cheaper, I would use a Ford type solenoid. They are much heavier duty and should be longer lasting. I have had "cube" relays fail running driving (actually aircraft landing) lights. I would install it as you stated. Adding a diode on the solenoid will prevent damage to electronics. I don't remember how I installed the diodes, but hopefully BoogietheCat will post the "how to". He is the one that told me how to do it.  Jack
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« Reply #18 on: April 04, 2007, 07:59:51 AM »

If you install a starter relay or solenoid, there is no need (in my opinion) to install a heavier duty starter switch. The very low energizing current of the relay will not harm the starter switch and there is not enough inductive kick back from the small coil to require a diode.

 Having said that, a diode across the starter relay would not hurt anything,  but as Jerry said, we went a loooooong time without the benefit of the shunt diodes. LOL

Probably in the olden days, long before even the invention of the diode, the contacts were much heavier duty to be able to better absorb the arc caused by the inductive kickback.

Richard


OK guys, be nice now. Boggiethecat is probably very right, the problem is I don't understand a word he said. That's my problem. Electricity. I have a handle on 120 but 12 volt stuff can be very confusing for me. So here we go again.

I have determined from all your posts that I have wired my ignition switch incorrectly. (Understand that our bus sat in a field for 10 or 12 years wide open, there, the furry birds with no wings scratched and ate at every piece of wiring in the entire coach. I spent months removing every inch of wiring and replacing it as I needed it.) There are 2 8D batteries that supply power to the dash where I have a momentary on rocker switch that goes back through the rear electrical panel box and then on to supply power to the starter selenoid. N0 relay. Not bypassed, no relay. I guess that's where I went wrong. Now I want to fix it.

I understand about the little cubed relay and it sounds cheaper than the Ford firewall style starter relay. But wouldn't I be better off to #1 replace the starter switch with a heavy duty ignition switch and then #2  add a Ford style relay to feed the starter selenoid? I guess I would place the Ford style relay in the rear electrical panel box and then #4 run heavier wire to the starter selenoid from there?

Thanks for all your suggestions.

Dave Siegel
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Dallas
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« Reply #19 on: April 04, 2007, 08:25:37 AM »

Dave,
YOur bus at one time had a starter relay in the engine control box.
I have a master parts book for many of the older models, including transits and parlor coaches.... pretty much everything from PD2903 up to PD4104 and TD 3209 to TD5104 all of them had a relay.
It should look a lot like a horn relay or a relay on one of the old cars/trucks.
The part number in the book is 1116852.

I understand why some people temporarily disconnect the relay, but I've seen too many that have left it that way and end up burning something up. In your case it's the switch.
Just remember, the relay takes the load off the switch and creates a buffer to keep from letting the smoke out of stuff.
In your case, since you aren't using a relay, your switch is acting like a circuit breaker, being the weakest link in the circuit, it dies, allowing the wiring to live. If you put a heavier switch in, you may no longer have a safety device there and the wire can burn in many bad places.

Please be careful!

Dallas
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DavidInWilmNC
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« Reply #20 on: April 04, 2007, 08:56:58 AM »

My bus is 30 years old and has one of those chrome heavy duty push buttons for the starter (it works through a solenoid in the engine compartment).  From the looks of it, it hasn't ever been changed.  Good Luck, TomC

That's exactly what I was going to say.  Mine is just a basic MCI chrome pushbutton that looks original.  I'm sure you can pick up one of these from Luke for cheap.  Also, I've seen momentary toggle switches with high DC current ratings that might help.  They seem (to me) to be sturdier than rocker switches.  Does your bus have a toggle for on/off, or does the rocker do it all, like on most generators (off/run-on/start)?  Good luck with it.

David
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boogiethecat
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« Reply #21 on: April 04, 2007, 09:49:51 AM »

Pie in face... Stan pointed out to me (privately) that I 'd swapped the words "anode" and "cathode" in my post.  Oops, it's now correct.  I did get the physical description right.  Guess I'm gettin old!!!

Stan also pointed out that 3 amp diodes might be a better option.  They're harder to find but physically they're more stout and there'd be nothing wrong with using them.  I acutally have a ton of 3 amp 400 volt fast diodes that I've offered to you guys before, for the price of a SASE to my PO box.  I'll send anyone some if they want...
Gary Stadler
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Here's a couple diagrams for those who need to see one.  First is one that is probably the most common, just a solenoid driving the starter. The second is how you'd put a cube relay in, on a system that has a solenoid built on to the starter motor.  Both diagrams show where you'd put diodes.



Cube relays- intersestingly I've seen many variations on how they have their internal diode connected.  Mostly it's as in diagram two, so you have to be careful to hook (+) to terminal 85 and (-) to 86.   Many these days incorporate an MOV varistor instead of a diode... it does much the same function but has no polarity- these are the best as you don't have to worry about it at all.  And then I've seen some cube relays that had the diodes "shown" installed the way they should have been but actually physically installed backwards, resulting in a big poof when energized.  They are all kinda cheepo and you have to watch your back when using them Smiley
« Last Edit: April 04, 2007, 09:56:06 AM by boogiethecat » Logged

1962 Crown
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« Reply #22 on: April 04, 2007, 01:59:44 PM »

1)   Diode will not prevent Daveís under (current) rated switch burn-out.
2)   No harm to add diode but not necessary when solenoidís armature is fully inward to avoid higher than normal spike feed back voltage. However all vehicle that has electronic system devises within should have diode between coil's pos to grd. PS..I recorrected my earlier statement instead of "between switch contacts"
3)   Momentary current is near 50 amps until its armature fully inward (engaged) than it reduce to about 8 amps at 12v.
4)   Experience has always been best the teacher.

FWIW

Sojourn for Christ, Jerry

« Last Edit: April 05, 2007, 04:22:05 AM by Sojourner » Logged
Hartley
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« Reply #23 on: April 04, 2007, 06:00:23 PM »

Some cube relays 30 amp have MOV's instead of diodes, Makes no difference then which
is hook to ground....

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« Reply #24 on: April 04, 2007, 08:35:43 PM »

Dave,

I have to disagree completely with Jerry. The 4104 has a small relay in the rear electrical compartment and a big solenoid on the starter. I just spent most of today looking at that compartment and am really sick of it right now!! The relay allows a very small current to run about 50' through small wires.

The starter relay is located next to the reverse relay and serves the same purpose. They look alike and probably are the same relay since both are used only for a few seconds at a time.

The purpose of the relay is to save the starter panel switch from the exact problem you are having. You don't need heavy duty anything in the panel starter switch circuit.

You can install the key type starter if you want a lock but that would be the only reason for it.

I don't really understand the diode stuff because these things went for many years with no diodes and it is a mystery to me why they need them now?
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boogiethecat
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« Reply #25 on: April 04, 2007, 08:51:22 PM »


I don't really understand the diode stuff because these things went for many years with no diodes and it is a mystery to me why they need them now?


Simple Gus, years ago manufacturers got away without them and things worked Ok, but nowadays they are used everywhere and things work better (and more reliably).  There were also many years without GPS, onboard computers, digital dash gauges, entertainment systems and oh yeah, electronically controlled engines.  In those days one could get along with some really nasty spikes in your electrical system and not hurt things, and replace switches and buttons that ate it.  But these days are different and diodes are really a good thing to install if you don't already have em!! They just clean up an act that needs to be cleaned up...
 
Just as one simple example, I originally installed a 100A solenoid to join my house battery banks to the engine starting battery so my alternator could charge both while on the road.  Lots of people do that.  I did not put a diode across the coil... until one day, the spike generated from switching off that solenoid took out my $400 CD/DVD player.  It went from happy music to dead duck in less than a second.  From that day on, ALL solenoids on my bus  (and any relays on my bus as well) have diodes!!!!  Additional things that should get them: Jake solenoids, fan clutches, to some extent DC motors... basically anything with a coil. They all make spikes.
« Last Edit: April 04, 2007, 08:59:51 PM by boogiethecat » Logged

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« Reply #26 on: April 05, 2007, 12:55:11 AM »

Just want to say that it's guys like Gary and Jerry that make these BBS's so great - thanks again
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« Reply #27 on: April 05, 2007, 09:48:52 AM »

Some cube relays 30 amp have MOV's instead of diodes, Makes no difference then which
is hook to ground....



What is a MOV?
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boogiethecat
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« Reply #28 on: April 05, 2007, 09:56:33 AM »

Metal oxide varistor
They are cheap, supress voltage spikes, have no polarity issues, come in sizes ranging from very tiny to gigantic, and they work well.
They are the basis of almost all power line surge supressors

There are a number of ways to supress voltage spikes of the nature we've been talking about, amongst them plain vanilla diodes, MOV's, transorb devices (also known as avalanch diodes) and for the really nasty stuff (lightning), gas discharge tubes.  Each has benefits and drawbacks that are probably a bit "off topic" with respect to this thread.
 In simple terms, MOV's are easer to use because they don't have polarity problems, but diodes do a better job of getting rid of inductive spikes if properly chosen and will definitely last longer, because MOV's degrade just a bit with every surge that they soak up- diodes don't.

For a really thorough (but poorly written in terms of understandability) writeup on MOV's, check this

http://en.wikipedia.org/wiki/Metal_oxide_varistor
« Last Edit: April 05, 2007, 10:08:11 AM by boogiethecat » Logged

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Dave Siegel
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« Reply #29 on: April 05, 2007, 02:25:02 PM »

Thank you everyone for the great wealth of information. As usual, you came through.A lot of it I don't understand at all, but I can figure it out with the drawings provided. Thank you, I'll let you know how it works out.

Dave Siegel
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Dave & Jan Siegel    1948 GMC  "Silversides"
               Naples, Florida
   Dave is Host to the "Help Assist Pages"
  (Free roadside help for Bus Conversions)
         www.help-assist-list.com
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