14 replies to this topic

[Kirbert]

My DiFalco has ESP -- Extreme Stopping Power.  When this switch is engaged, power from the wiper at the brake end of its travel (not from the brake contact!) goes through a diode to a relay coil.  The relay energizes and connects the red and black leads together right at the power block, cutting the brake pot and all its associated wiring (including the wiring from power block to controller handle and back) out of the circuit.

 

I love how this thing works.  I'm not as thrilled with the brake operation with the ESP turned off, utilizing the conventional brake contact and pot.  I was getting inconsistent braking action which I eventually traced to the brake contact itself, in this case a flat brass surface on the trigger contacting a copper bump.  Both brass and copper get corroded and the ohmage of that contact varies -- which means the braking action varies.  A formula for coming off in the turns.

 

I replaced the copper bump with an actual contact robbed out of an electrical switch.  My braking action immediately got considerably more consistent.  I was also thinking about soldering a piece of thin stainless over the flat brass piece but never got around to it.

 

I should also point out that I've blown the brake pot on this controller about four times.  Sometimes my stupidity in connecting it up wrong, sometimes something else going on.  Once was a blown diode.

 

To the point of this thread:  I decided that if the ESP works so well for max brake operation, why not something similar for all brake operation?  I purchased another tiny relay sorta like the one used for the ESP, but I installed this one in the controller handle rather than in the power block.  I connected it to the off position of the ESP switch, so "on" operates the ESP relay while "off" operates this new relay in exactly the same manner.  I added a diode in the circuit just as the ESP circuit has, presumably to prevent the relay from energizing if the controller is hooked up wrong.  This relay works exactly the same way the ESP relay does except that it utilizes the brake pot.  I disconnected the brake contact on the trigger, so that contact remains the physical stop for trigger motion but has no electrical function.

 

I am thrilled with how well this works!  Suddenly I'm a better driver, being able to dive deep into corners lap after lap without coming out.

 

One thing worth noting:  When there's a track call and power is cut to the track, you have NO BRAKES.  If the track call happens just as you're diving into a corner, the car WILL be coming out!  Fortunately, there's a track call going on, so some corner marshal just has to put your car back on before the race resumes.

 

I expect this relay will also help prevent the brake pot from getting blown, as the relay won't energize to connect it if the power is hooked up incorrectly.  There might still be some way to blow that pot, but I believe it's far less likely.

 

For those without an ESP switch:  I believe you could make a similar mod by controlling a relay with the regular brake contact.  Variability in the contact's ohmage would make no difference, as it simply turns the relay on and off.  The relay contacts will provide consistent braking action.

 

Comments?

[Dave_12]

I clean the brake contacts on my Difalco regularly otherwise i get inconsistent brake or in some cases no brake at all . 
So far i have had no need to use the ESP . 

[Eddie Fleming]

Kirby 

 Back in the days of old when Racers were bold and electronic controls were not yet invented. It was not uncommon to replace the brake contact with a micro switch. The only trick with that is getting it adjusted so the switch actuates and deactivates  at the proper point in the trigger travel. ( you don't want the switch on when you start hitting the power bands.) Your relay has some advantages but with the switch you still have brakes after the power goes off. Once in a while the timing of a track call and no brakes can cause a big damaging hit.

 

With my Difalco's I clean the contacts and run a strong enough spring to get a good solid contact. And I try to be sure I get my finger all the way off the trigger when breaking. 

[JerseyJohn]

My DiFalco has ESP -- Extreme Stopping Power.  When this switch is engaged, power from the wiper at the brake end of its travel (not from the brake contact!) goes through a diode to a relay coil.  The relay energizes and connects the red and black leads together right at the power block, cutting the brake pot and all its associated wiring (including the wiring from power block to controller handle and back) out of the circuit.

 

I love how this thing works.  I'm not as thrilled with the brake operation with the ESP turned off, utilizing the conventional brake contact and pot.  I was getting inconsistent braking action which I eventually traced to the brake contact itself, in this case a flat brass surface on the trigger contacting a copper bump.  Both brass and copper get corroded and the ohmage of that contact varies -- which means the braking action varies.  A formula for coming off in the turns.

 

I replaced the copper bump with an actual contact robbed out of an electrical switch.  My braking action immediately got considerably more consistent.  I was also thinking about soldering a piece of thin stainless over the flat brass piece but never got around to it.

 

I should also point out that I've blown the brake pot on this controller about four times.  Sometimes my stupidity in connecting it up wrong, sometimes something else going on.  Once was a blown diode.

 

To the point of this thread:  I decided that if the ESP works so well for max brake operation, why not something similar for all brake operation?  I purchased another tiny relay sorta like the one used for the ESP, but I installed this one in the controller handle rather than in the power block.  I connected it to the off position of the ESP switch, so "on" operates the ESP relay while "off" operates this new relay in exactly the same manner.  I added a diode in the circuit just as the ESP circuit has, presumably to prevent the relay from energizing if the controller is hooked up wrong.  This relay works exactly the same way the ESP relay does except that it utilizes the brake pot.  I disconnected the brake contact on the trigger, so that contact remains the physical stop for trigger motion but has no electrical function.

 

I am thrilled with how well this works!  Suddenly I'm a better driver, being able to dive deep into corners lap after lap without coming out.

 

One thing worth noting:  When there's a track call and power is cut to the track, you have NO BRAKES.  If the track call happens just as you're diving into a corner, the car WILL be coming out!  Fortunately, there's a track call going on, so some corner marshal just has to put your car back on before the race resumes.

 

I expect this relay will also help prevent the brake pot from getting blown, as the relay won't energize to connect it if the power is hooked up incorrectly.  There might still be some way to blow that pot, but I believe it's far less likely.

 

For those without an ESP switch:  I believe you could make a similar mod by controlling a relay with the regular brake contact.  Variability in the contact's ohmage would make no difference, as it simply turns the relay on and off.  The relay contacts will provide consistent braking action.

 

Comments?

 

How did you wire it.

[wizardgm]

Here is my solution shown in pictures.

I add a piece of braid to the brake contact on the trigger and reshape the contact on the frame.

Been using for quite some time now.

 

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To the point of this thread:  I decided that if the ESP works so well for max brake operation, why not something similar for all brake operation?  I purchased another tiny relay sorta like the one used for the ESP, but I installed this one in the controller handle rather than in the power block.  I connected it to the off position of the ESP switch, so "on" operates the ESP relay while "off" operates this new relay in exactly the same manner.  I added a diode in the circuit just as the ESP circuit has, presumably to prevent the relay from energizing if the controller is hooked up wrong.  This relay works exactly the same way the ESP relay does except that it utilizes the brake pot.  I disconnected the brake contact on the trigger, so that contact remains the physical stop for trigger motion but has no electrical function.

 

I expect this relay will also help prevent the brake pot from getting blown, as the relay won't energize to connect it if the power is hooked up incorrectly.  There might still be some way to blow that pot, but I believe it's far less likely.

 

For those without an ESP switch:  I believe you could make a similar mod by controlling a relay with the regular brake contact.  Variability in the contact's ohmage would make no difference, as it simply turns the relay on and off.  The relay contacts will provide consistent braking action.

 

Comments?

 

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[Kirbert]

 

How did you wire it.

 

Starting at the unused end of the ESP switch, I connected a diode pointing away from the switch (diodes are directional).  From the diode to one of the coil terminals on the new relay.  I connected the other coil terminal to the red lead.

 

The other three connectors on this relay are common, NO, and NC.  NC is not used in this application.  I connected the common to the red lead, which means both the common and one coil terminal are both connected to the red lead.  The NO terminal is connected to the brake pot, with the other terminal of the brake pot being unaltered going to the black lead.  And, remembering to disconnect the wire from the brake contact on the trigger.  Done.

 

I'm actually thinking of connecting the brake contact back up using a really thin piece of wire, something that would blow before the pot if the controller were hooked up wrong.  That would give me brakes when the power is cut for a track call.  The rest of the time it wouldn't see any current at all, as the relay would close before the brake contact does.

[Eddie Fleming]

I like your idea of reconnecting the brake contact so you still have breaking with power off. 

[Kirbert]

One thing we have learned:  I'm not the only one concerned with consistent brake operation.  Perhaps DiFalco et al should take note and pay more attention to this issue.

 

There's another thread on silver contact buttons.  Silver is great for conductivity, but conductivity is not the concern here.  You don't care all that much what the resistance is through those points, you just want it to be exactly the same, time after time, whether you release the trigger with a snap or gradually lower it onto the brake stop.  When I connected a VOM to the red and black leads, I'd get a different reading every time!  Miserable.  That's why I delved into trying to improve it.

 

If I weren't going with this relay scheme, what I would consider the ideal setup would be stainless steel contacts, both on the moving trigger and on the stationary button it stops against.  Stainless steel may not be a great conductor, but it doesn't corrode so every brake application should be exactly the same.

 

Gold would work too, I guess, but I'd want it thick enough not to rub through, and that'd probably be costly.

[Eddie Fleming]

Just a few words for you to ponder Kerby.

 

 FET brakes as on a 3rd eye or others.

[wizardgm]

One thing we have learned:  I'm not the only one concerned with consistent brake operation.  Perhaps DiFalco et al should take note and pay more attention to this issue.

 

There's another thread on silver contact buttons.  Silver is great for conductivity, but conductivity is not the concern here.  You don't care all that much what the resistance is through those points, you just want it to be exactly the same, time after time, whether you release the trigger with a snap or gradually lower it onto the brake stop.  When I connected a VOM to the red and black leads, I'd get a different reading every time!  Miserable.  That's why I delved into trying to improve it.

 

If I weren't going with this relay scheme, what I would consider the ideal setup would be stainless steel contacts, both on the moving trigger and on the stationary button it stops against.  Stainless steel may not be a great conductor, but it doesn't corrode so every brake application should be exactly the same.

 

Gold would work too, I guess, but I'd want it thick enough not to rub through, and that'd probably be costly.

Over many years I have worked on / repaired MANY types of controller brands, not just any one particular brand, so yes it ia a common issue.

I used to work for a company that used tungsten contacts for a high current switching task.

 

These new electronic controllers with contact-less triggers (Hall effect electronics) are getting very close to perfection, but even these have issues with the mechanical brake stops moving and affecting the brakes.

 

So, nothing will be perfect.   

Just my humble opinion.

[Paul5097]

One thing we have learned:  I'm not the only one concerned with consistent brake operation.  Perhaps DiFalco et al should take note and pay more attention to this issue.

 

There's another thread on silver contact buttons.  Silver is great for conductivity, but conductivity is not the concern here.  You don't care all that much what the resistance is through those points, you just want it to be exactly the same, time after time, whether you release the trigger with a snap or gradually lower it onto the brake stop.  When I connected a VOM to the red and black leads, I'd get a different reading every time!  Miserable.  That's why I delved into trying to improve it.

 

If I weren't going with this relay scheme, what I would consider the ideal setup would be stainless steel contacts, both on the moving trigger and on the stationary button it stops against.  Stainless steel may not be a great conductor, but it doesn't corrode so every brake application should be exactly the same.

 

Gold would work too, I guess, but I'd want it thick enough not to rub through, and that'd probably be costly.

The problem isn't corrosion of the brake contact, it is arcing. The brake contact is shorting the voltage the motor generates when in braking. Turn out the lights when driving and you can see the brake contact arc every time the brakes are applied. Stainless steel would have the same issue.

 

For the best brakes, cleaning the brake contacts should be part of your pre-race routine.

[Bill Seitz]

The usual problem I find with brakes that are not working or working inconsistently has nothing directly to do with the brake contact and everything to do with the trigger return pressure and the trigger actually engaging the brake contact consistently. The trend for very light trigger actions can contribute. I pay particular attention to the mechanics of my controller trigger to make sure the trigger always returns to the brake contact with even the slightest pressure movement off brakes. Every instance of inconsistent brakes I've had were caused by this, and it was fixed either by removing a source of trigger binding or interference or by increasing the return spring force.

 

The usual cause of brake contact arcing is that the throttle is shorting through the brake contact, not the very small amount of energy the motor creates on dynamic braking. Resistor controllers were notorious for this because the wiper button often reached the brake contact while still bridging across to the first bands of throttle. It's very important to make sure the throttle is turned off before the brake circuit is engaged (the wiper button has left the first throttle band before it reaches the brake band or trigger contact reaches the brake contact), as this creates a direct short between throttle power supply and brake ground through both the throttle/power transistor and the brake pot, relay, or brake transistor. There are usually current limiters or fuses which may blow first, but the brake pot can be blown by this sort of throttle short especially when it occurs over and over. If the brake contacts are arcing, think what this is doing inside a tiny brake relay that has contacts much smaller than the controller brake contact.

[Jim Difalco]

Just back from a couple days off for Christmas so I thought I would clear up a few things.

 

1) First racers need to realize how many times your brake contact is engaged during one race. Multiply your laps by how many times you hit the brake contacts per lap plus stopping for accidents and you will see it could be over 1000 just for a short race.

 

2)Second, this is DC power and arcing will happen even with the small dynamic braking load from a motor and multiply this by 1000 times and the number of months or YEARS before a racer actually cleans their contacts and you can see why this is an issue. There is a reason the solution to this is the first line under my troubleshooting in my instructions. I have racers who have never cleaned their contacts and do not know where they are or think I am talking about the wiper bands.

 

3)I caution racers about trigger spring tension being too light but my triggers do not bind up on my factory controllers unless they have been messed with. Most of the binding I have seen was with triggers scrapping on the inside of Parma handles from the slop in the trigger pins or too heavy a wire gauge on the trigger.

 

4)Hard stainless steel contacts that Kirbert suggested are a horrible material for contacts and will pit up very quickly.

 

5)Throttle shorts with the first band and the brake contact are not possible on my controllers as they all have a thin dead band. This also prevents any shorts when the ESP brake relay engages.

 

6)Kirbert says that using this relay to turn on the brake circuit will save the brake rheostat from being damaged, it will not. What will happen is the contact arm inside the relay will blow in half or the relay contacts will weld closed if the controller is connected incorrectly and you dump full battery power across the brake circuit. Weather the relay blows first or the brake rheostat may be damaged or the fuse opens first is the question.

 

I do think about this issue. I have various concepts I am playing with to improve the consistency of the contact operation and when they are ready Slotblog readers will be the first to know. And of course I will try to make anything I come up with adaptable to all my previous controllers if possible. In the meantime please remove your front handle and clean your brake contacts and the back of your trigger of any black arcing!!!!! How often depends on how much you race.

[Kirbert]

 

The usual cause of brake contact arcing is that the throttle is shorting through the brake contact, not the very small amount of energy the motor creates on dynamic braking. Resistor controllers were notorious for this because the wiper button often reached the brake contact while still bridging across to the first bands of throttle.

 

The DiFalco with ESP has a dead band between the first band of throttle and the brake band.  It's still possible to get a short if the wiper button is wide enough to contact all three of these bands at the same time.  I try to make sure the wiper button is not that wide by filing bevels on the sides, leaving a narrower contact area.

 

While I was adding the brake relay, I considered using the NC contact to somehow cut the throttle.  Since an NC contact will always open before the NO contact closes, this would ensure no shorting.  I didn't think about it long enough to figure out how to do it, though.  If DiFalco didn't do it for the ESP, I figured it wasn't critical.

 

I've fiddled with some Third Eye controllers -- in fact, I have one in hand right now I was repairing for a friend -- but I must confess I don't fully understand how they work.  I know the wiper is ***always*** on a throttle band, so when the brakes are applied it must be somehow disabling the throttle.  It never makes it to full throttle on the resistor coil, either, so the full throttle contact bypasses the resistor coil altogether to provide wide open throttle.

 

Can someone tell me how a Third Eye provides brakes when a track call cuts the power?

[Eddie Fleming]

 

Can someone tell me how a Third Eye provides brakes when a track call cuts the power?

I suspect the cap in the controller handle supplies voltage for a short time to power the FET brakes.