Author Topic: Abandon Starter Relay! (?)  (Read 31045 times)

Offline TrueAce

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Abandon Starter Relay! (?)
« on: December 11, 2015, 06:30:08 PM »
Starter Relays appear to be among the TOP topics of discussion......really, just look at all the posts! Does the concept of the most critical link in the starter system "fusing contacts" every time there is lower battery amperage, or a random ground, seem right? Yeah, I know it's a 30 year old bike, but really, is there a more vulnerable electric component in a K75/100 than the starter relay?
After too many failures & replacements ($), I am thinking there is a way to re-engineer the starter system to fuction without an expensive Bosch relay.....hear me out.
So the start switch control input wires connect to the starter relay, connected to battery-in, connected to starter-out. And points get confused & fused. Why not direct wire the battery-starter connection to an appropriately amp single-throw switch, like race vehicles. Ignition "ON", Kill switch "ON", single-throw switch "ON" activates starter........ZOOM. Why does it all have to go throw an expensive, vulnerable, non-solid state/contact fusing Bosch starter relay? Hey?
  • Florida
  • '85 K100GS, '85 K100RSSC,', '94 K1100RS,'10 S1000rr,'14 Ural Sidecar, '15 R Nine T

Offline rbm

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Re: Abandon Starter Relay! (?)
« Reply #1 on: December 11, 2015, 09:08:28 PM »
Because your mechanical switch remedy has no safety feature to prevent the starter from engaging with the engine running.  The starter relay is grounded through the ICU which removes the ground if the engine RPMs are higher than 770.

The best remedy is to find a replacement relay with a lower hold-in voltage than the BMW standard one.  That way, a lower battery terminal voltage (due to weak battery) will not allow the starter relay to oscillate around the hold-in voltage.

What happens to cause the starter relay to weld:
If we look at what is happening on our bikes when we push the starter button the starter relay coil effectively receives current via the starter switch and a whole bunch of connections, if the voltage is too low the relay will not pull in because the voltage required to pull in a relay is higher than the voltage required to keep it closed (called its hold in voltage). At that point we push the button and nothing happens, if there is enough voltage to pull in the relay then the following takes place.

With a weak battery there can be just enough voltage to pull the starter relay in, it pulls in and the relay contacts close with a spark at the moment of contact, at that point voltage starts to flow into the starter motor.

The current draw of the starter is huge and as a result the voltage supplied by the battery can sag down below the hold in voltage of the starter relay so the armature of the starter relay starts to release from the coil thereby weakening the spring pressure holding the relay contacts closed until the relay contacts separate and an arc forms momentarily between the relay contacts and then extinguishes. At that point current to the starter motor stops and the battery voltage rises up to the point where the relay pulls in again and the cycle recommences. The high speed pulsing or chattering of the relay and the sparking at the contacts allows them to weld shut at the point when there is sufficient molten relay contact material present when they close and the arc stops. At that precise point as the contact is closed the molten metal freezes and the relay contacts are welded closed and as a result the starter is now permanently running until the battery goes flat.
  • Regards, Robert
Toronto, Ontario

1987 K75 - Build Blog @http://k75retro.blogspot.ca/

Offline Laitch

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Re: Abandon Starter Relay! (?)
« Reply #2 on: December 11, 2015, 09:41:37 PM »
Another affirmation that K-bikes are made to be ridden and ridden plenty, or else trickle charged during prolonged static admiration. Thanks for bringing the synopsis here, Robert.
  • Along the Ridley in Vermont.
  • 1995 K75T 68,000 miles
I wept because I had no radials until I met a man who had no splines.
http://www.motobrick.com/index.php/topic,296.msg53303.html#msg53303

Offline TrueAce

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Re: Abandon Starter Relay! (?)
« Reply #3 on: December 11, 2015, 10:01:19 PM »
Thanks, Robert, for your always concise response. I turn to the race toggle solution because a solid starter response is not effected by the input switch, yet when I introduce a lesser amp switch between starter wire and power, no problem starting, and it doesn't run on. Why not eliminate the relay.......what else does it do that a manual appropriate amp switch manually would do?
Ignition ON....check.......Kill switch ON......check.....intermittent starter switch ACTIVATE, bike starts. Can I eliminate the starter relay, and with lights direct wired, the shed relay, too? what am I not understanding, with all the handle bar switches relocated to under seat? Like headlight, i want to direct wire the starter. Guide me guru's, please!
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  • '85 K100GS, '85 K100RSSC,', '94 K1100RS,'10 S1000rr,'14 Ural Sidecar, '15 R Nine T

Offline Laitch

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Re: Abandon Starter Relay! (?)
« Reply #4 on: December 11, 2015, 10:42:22 PM »
From my understanding of Robert's post, you can do that which you propose; however, doing so eliminates a feature designed to prevent accidental energizing of the starter and the resulting havoc, unlikely though it seems.

I wonder if I've got that right. I think it's better for me to just keep the battery charged and be mindful of how I operate the switch. A cheaper relay would be nice though, in case I get distracted.
  • Along the Ridley in Vermont.
  • 1995 K75T 68,000 miles
I wept because I had no radials until I met a man who had no splines.
http://www.motobrick.com/index.php/topic,296.msg53303.html#msg53303

Offline TrueAce

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Re: Abandon Starter Relay! (?)
« Reply #5 on: December 11, 2015, 11:00:55 PM »
Laitch, I understand what you're saying. Everything I ride is on a trickle. The K100 is my project bike that I
 continue to experiment with. Having successfully removed all the handlebar switches to under-seat, I decided to upgrade that to a lighted array of manual switches......will post photos tomorrow. But the starter relay still bugs me. On a single switch throw (on/-spring back....like on race cars), there will be no continuous run with the starter, or accidental engagement while running. Seems the starter relay, and load shed relay, would be superfluous. I've bench tested with switches, using a beefy starter button, no problem activated the starter. But the damn starter relay just seems unnecessary if you apply race car starter wiring principles.
On top of that K100 story, then I pull the K75 out of the garage after two weeks idle, starts right up, idles for 5 minutes then quits. Start up yields click-click, so after a overnight charge, no click ,no start.....another low battery plus probably fused relay. That's when I began thinking there must be a better way to wire k bike starters than going through an expensive Bosch relay. Surely somewhere in 30 years of K bikes somebody has discovered a better way. 
  • Florida
  • '85 K100GS, '85 K100RSSC,', '94 K1100RS,'10 S1000rr,'14 Ural Sidecar, '15 R Nine T

Offline Laitch

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Re: Abandon Starter Relay! (?)
« Reply #6 on: December 11, 2015, 11:42:45 PM »
Well, if there's zero chance of accidental energizing with what you're proposing then I'm not certain I understand Robert's post.

As far as the K75 problem, all I can say is idle bikes are the devil's tools. I think they're especially vulnerable when they're stored for long periods in the comfort of a warm space. When I put mine up for winter, it has always been ridden hard the day before that. It sits in an unheated shop that's far from air-tight although inside is way more comfortable than outside in windchill. The interior temp sometimes goes double digits below 0ºF. The muffler is plugged, the battery removed to be stored and charged once a month off-site in a heated room and that's it. When the temperature is tolerable, I do whatever maintenance is on the schedule until spring. The more I read here, the more I'm thinking it's a miracle that I can just gas it up and go every spring. 

I keep reading about the problems arising from corroded, dirty or loose electrical connectors and components. I had one of those loose ones that I fixed in two seconds once I knew where to look. I'm starting to think that riding my bike at a wide range of speed and in wet weather fosters its durability and keeps those miracles coming.
  • Along the Ridley in Vermont.
  • 1995 K75T 68,000 miles
I wept because I had no radials until I met a man who had no splines.
http://www.motobrick.com/index.php/topic,296.msg53303.html#msg53303

Offline TrueAce

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Re: Abandon Starter Relay! (?)
« Reply #7 on: December 11, 2015, 11:58:57 PM »
Yeah, Laitch, I think the battery just reached the end of its service life, but I tried to restart and froze the starter relay,that's my next maintenance task, already have the battery & relay coming. But my K100 project is a non-stock project that I am going to apply my Dale Earnhardt starter switch concept to next! News & photos to follow!
  • Florida
  • '85 K100GS, '85 K100RSSC,', '94 K1100RS,'10 S1000rr,'14 Ural Sidecar, '15 R Nine T

Offline Scud

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Re: Abandon Starter Relay! (?)
« Reply #8 on: December 12, 2015, 12:35:24 AM »
I was able to get replacement relays for my Moto Guzzis for super-cheap through Digi-Key's website. Somebody else, who understands electronics better than I do, figured which ones worked. Here's the link in case somebody has the technical knowledge to figure out exactly what relay is needed:

http://www.digikey.com/
  • Carlsbad, CA
  • 1992 K75s. 2002 Moto Guzzi V11 Scura, 2003 Moto Guzzi V11 LeMans. 2007 Husqvarna TE450

Offline Laitch

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Re: Abandon Starter Relay! (?)
« Reply #9 on: December 12, 2015, 01:33:08 AM »
OK. Here's something for starter relay welding victims to contemplate—a K75 starter relay (at least the part number of the one pictured at MAX, although with some additional suffix characters)—at an interesting price. Minimum order of two.
http://www.digipart.com/part/V23232A0001X005-EV-263
  • Along the Ridley in Vermont.
  • 1995 K75T 68,000 miles
I wept because I had no radials until I met a man who had no splines.
http://www.motobrick.com/index.php/topic,296.msg53303.html#msg53303

Offline TimTyler

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Re: Abandon Starter Relay! (?)
« Reply #10 on: December 12, 2015, 02:01:23 AM »
The sticky starter relay is definitely a pain. I've tried everything, fresh batteries, super heavy duty battery leads, 100% trickle charging, cleaned ground connectors and when I least expect it, it'll stick. Most often right after fueling up. I carry a spare relay, and both the installed and spare have been disassembled, had their contacts sanded and reassembled. In the last 10k miles I've probably only had it stick three times, maybe four. I carry a breaker bar in the tragkorb (with a socket for rear wheel changes) and I use that to whack the side of the relay box and un-stick the starter relay. I actually drew an X in silver Sharpie on my relay box so I'd know where to whack it :)

I direct line switch to the starter is a novel idea.

Offline F14CRAZY

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Re: Abandon Starter Relay! (?)
« Reply #11 on: December 12, 2015, 12:33:11 PM »
I've heard about sticking starter relays, and I believe what I've heard about them, but I haven't had the issue. I've had low batteries turn the starter slowly before and have had a couple times where the battery was able to just turn it but stop, but still no fused relay
  • Grand Rapids, MI
  • '87 K75C
'87 K75C w/ Pichler V1 fairing. LED's, CATZ driving lights, Audiovox cruise, LT top case, tons of other mods by Drake...


Offline TimTyler

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Re: Abandon Starter Relay! (?)
« Reply #12 on: December 12, 2015, 01:00:27 PM »
What brand of breaker bar do you use, Tim?

It's a 24" 1/2" bar. Maybe Craftsman or Harbor Freight.

F14Crazy - Yeah, the relay sticking is not predictable on my bike. I've also had a low battery turn the engine slowly without the relay sticking, and I've had a strong battery cause the relay to stick. It's happened in cold and hot weather. Almost every time the relay stuck I was starting after a quick break after hard riding, like at a gas station or rest stop. It happened fairly regularly before the battery cable upgrade but not so much anymore. I also cleaned/overhauled the starter when I installed the new cables. (Easy job if you can get the screws out without stripping them.)

A couple of times I rode with the relay stuck / starter running for miles before I noticed something wrong. If you don't notice the starter's grinding noise over the engine sound the only other indication is that the lights and speedo are probably off (thanks to the load shed relay).

Offline TrueAce

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Re: Abandon Starter Relay! (?)
« Reply #13 on: December 12, 2015, 01:57:32 PM »
TimTyler......did you experience starter relay problems on your cross-country trip? The unreliability of the K100/75 starter relay is so uncharacteristic of my long BMW experience.
  • Florida
  • '85 K100GS, '85 K100RSSC,', '94 K1100RS,'10 S1000rr,'14 Ural Sidecar, '15 R Nine T

Offline TimTyler

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Re: Abandon Starter Relay! (?)
« Reply #14 on: December 12, 2015, 02:37:15 PM »
TimTyler......did you experience starter relay problems on your cross-country trip?

Couple of times that I remember.

Offline F14CRAZY

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Re: Abandon Starter Relay! (?)
« Reply #15 on: December 12, 2015, 02:41:34 PM »
I hope this isn't going off topic but...

If you're on a trip or something and don't have access to a new relay, what can be done to work around the issue? Disconnect the starter and bump-start the bike?

I take it the starter relay is a sealed unit and you can't disassemble it and clean the contacts
  • Grand Rapids, MI
  • '87 K75C
'87 K75C w/ Pichler V1 fairing. LED's, CATZ driving lights, Audiovox cruise, LT top case, tons of other mods by Drake...


Offline rbm

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Re: Abandon Starter Relay! (?)
« Reply #16 on: December 12, 2015, 03:27:33 PM »
I was pointing out the reason why BMW chose a fragile starter relay - to implement a rider safety feature.  There are other safety features of the bike including sidestand interconnects, sidestand switches on later models, neutral detect, and the bulb monitoring unit, all designed to make riding the bike safer.  There's nothing to stop anyone who owns these bikes from defeating any or all of these safety features; in fact, it's often done.

Your idea of a SPST momentary toggle switch between a source of power and the starter.  If you implement your circuit, you'd most likely connect the switch between the battery and starter, I assume, with a large gauge wire to give the maximum umph. Right?

There was  a BMW service bulletin published in the mid-nineties that called for the use of a redesigned relay in police vehicles, I believe (Inge would probably know more).  I am not able to find that bulletin online.  It did not state exactly what the new relay did, but probably there was circuitry in the unit that stopped the contacts welding with a low battery condition.

F14, As for the starter relay, it's not sealed; it can be opened and serviced.  Depending on how it failed will determine whether it is salvageable or must be replaced.  In a pinch, you'd remove the relay from the relay box to stop the constant turning of the starter.  Come time to get it going, it should be possible to bump start the bike.
  • Regards, Robert
Toronto, Ontario

1987 K75 - Build Blog @http://k75retro.blogspot.ca/

Offline F14CRAZY

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Re: Abandon Starter Relay! (?)
« Reply #17 on: December 12, 2015, 04:41:21 PM »
Could you just use like a jumper wire in place of the relay?
  • Grand Rapids, MI
  • '87 K75C
'87 K75C w/ Pichler V1 fairing. LED's, CATZ driving lights, Audiovox cruise, LT top case, tons of other mods by Drake...


Offline The Mighty Gryphon

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Re: Abandon Starter Relay! (?)
« Reply #18 on: December 12, 2015, 05:22:31 PM »
It is no wonder these relays have problems.  You connect a 300+ CCA battery to a set of contacts rated for 150A. 

Here is an idea, replace the BMW relay with a real starter solenoid.

http://www.autozone.com/batteries-starting-and-charging/solenoid/duralast-solenoid/82182_0_0/?checkfit=true
  • In my garage in Marilla, NY
  • '94 K75RT Mystic Red, '92K100RS White, '94 K75S Dakar Yellow
Current:
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'94 K75S "Cheetos"
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Offline TrueAce

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Re: Abandon Starter Relay! (?)
« Reply #19 on: December 12, 2015, 06:39:09 PM »
Yes, that will work! Little big to hide in the delay box, but I've managed to put lithium battery in the box. You could fit the solenoid , hide the lithium elsewhere.
  • Florida
  • '85 K100GS, '85 K100RSSC,', '94 K1100RS,'10 S1000rr,'14 Ural Sidecar, '15 R Nine T

Offline rbm

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Re: Abandon Starter Relay! (?)
« Reply #20 on: December 12, 2015, 07:58:23 PM »
Could you just use like a jumper wire in place of the relay?
I was assuming that the relay had welded close.  It would have to be isolated from the circuit to stop the starter from continuously turning.  Was my assumption wrong?
  • Regards, Robert
Toronto, Ontario

1987 K75 - Build Blog @http://k75retro.blogspot.ca/

Offline F14CRAZY

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Re: Abandon Starter Relay! (?)
« Reply #21 on: December 12, 2015, 10:29:04 PM »
Could you just use like a jumper wire in place of the relay?
I was assuming that the relay had welded close.  It would have to be isolated from the circuit to stop the starter from continuously turning.  Was my assumption wrong?

Yeah...if the contacts weld the circuit would close and keep the starter spinning. But if you disconnect the relay and can't replace the relay like if you're on a trip can you use a jumper in place of the relay?
  • Grand Rapids, MI
  • '87 K75C
'87 K75C w/ Pichler V1 fairing. LED's, CATZ driving lights, Audiovox cruise, LT top case, tons of other mods by Drake...


Offline The Mighty Gryphon

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Re: Abandon Starter Relay! (?)
« Reply #22 on: December 13, 2015, 12:54:22 AM »
If you are careful and have a couple of small jewelers screwdrivers and some 400 or 600 grit paper, it is possible to pop the case on the starter relay.  Separate the contacts, and clean them up with a few passes of the paper.  I don't know if you'll get another 50,000 miles out of them, but they should get you home.
  • In my garage in Marilla, NY
  • '94 K75RT Mystic Red, '92K100RS White, '94 K75S Dakar Yellow
Current:
'94 K75RT "Ilsa, She Wolf of the SS"
'94 K75S "Cheetos"
'91 K100RS "Moby Brick Too

Offline F14CRAZY

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Re: Abandon Starter Relay! (?)
« Reply #23 on: December 13, 2015, 12:18:31 PM »
If you are careful and have a couple of small jewelers screwdrivers and some 400 or 600 grit paper, it is possible to pop the case on the starter relay.  Separate the contacts, and clean them up with a few passes of the paper.  I don't know if you'll get another 50,000 miles out of them, but they should get you home.

Doesn't hurt to keep some emery cloth on board
  • Grand Rapids, MI
  • '87 K75C
'87 K75C w/ Pichler V1 fairing. LED's, CATZ driving lights, Audiovox cruise, LT top case, tons of other mods by Drake...


Offline Martin

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Re: Abandon Starter Relay! (?)
« Reply #24 on: December 13, 2015, 03:58:31 PM »
I've had my k75 for approx 16 years .Just after I got it the relay stuck and the starter just kept cranking until the battery overheated & the side of the battery blewout.Battery acid everywhere lucky I had access to plenty of water.After it happened for the second time & I knew to disconnect the earth lead, resulting in one burnt finger.I have now fitted an in line battery isolator switch ( the smallest I could find).This has been fitted behind the side cover it required the cutting of the earth lead to accommodate the switch and soldering in two lug connectors.I can now isolate the battery and it can be used as a security device by removing the key.You can access the switch without having to remove the side cover.it is virtually invisible and would be even harder to see if you painted the removable switch black.Somebody else pointed out that he had a Ural which was fitted with one as standard. It was handy when you wanted to work on the bike & needed to isolate the electrics .I have posted pictures and installation instructions in the Workshop under Re: Starter relay stuck November 22nd.
Regards Martin
  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

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