Larry,
The newer brake controllers like the Prodigy, P3, Brakesmart, and others will tell you how much voltage is being supplied by the controller to the trailer brakes. That voltage varies according to how hard you press down on the brake pedal and the rate of deceleration of the TV.
Barney
2004 Sunnybrook 30FKS TT
Hensley "Arrow" 1400# hitch
2002 Ford F250 Super Duty, 7.3L PSD
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LarryJM on 05/31/08 03:37pm wrote: Please explain since as far as I know the magnets run off the DC voltage of the TV which is fixed depending on the charge of the TV battery and doesn't change and how does the voltage change and how and what are using to measure this increase in brake voltage.
Larry
The display on the P3 Prodigy shows the voltage. It can be controlled manually with the slide switch or automatically with the brake force. The higher the voltage, the more force on the brakes (magnets) If you have an older controller without a display, it would be a good investment to get a new one.
Az. Jim wrote: I won't consider myself an expert. However I drove a semi years ago when we didn't have "Jake" brakes, some did, but we didn't. Over the years I drove about 3 million miles, coast to coast. That was back in the days when a 220 cummins was a big power plant.
I found out, being extra cautious was the best policy. Number 2 method is the only way. I would suggest, on any mountain grade, if you have any concerns, come almost to a stop at the top. Choose a low, (or lowest gear), start down, if that gear seams too low, you can always select the next higher gear to procede down the mountain.
Remember, it's your life thats important and the time it takes to go down the mountain is not important.
I remember a mountain in W.V., years ago. I think its was Blue Mtn, that had a sign at the top that said, ALL TRUCKS MUST STOP, the sign went on to say something like, IN THE LAST 5 YEARS 6 TRUCKERS HAVE BEEN KILLED BY RUN-A-WAY TRUCKS. Belive me when you read that you stop and check everything out before heading, carfully, on down the mtn.
Very well said AZ Jim - similar to the quote in the Mountain Directory - You can go down a mountain many times too slow but only once too fast (and I'm paraphrasing).
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BarneyS wrote: Larry,
The newer brake controllers like the Prodigy, P3, Brakesmart, and others will tell you how much voltage is being supplied by the controller to the trailer brakes. That voltage varies according to how hard you press down on the brake pedal and the rate of deceleration of the TV.
Barney
Barney, your statement is not quite accurate. The topic of this discussion deals with braking downhill. Prodigy and P3 work off of a motion sensor that senses the deceleration of the tow vehicle, then adjusts the braking power according to the deceleration of the tow vehicle. Since this topic deals with hills, it has to be stated that it takes more brake pressure going down hill to create the exact same rate of deceleration as it does going uphill. Even when not towing, you have to hit your brakes harder when you are going down a steep hill.
Your statement is however accurate about Brake Smart. Brake Smart does place a sensor in the hydraulic brake line. It knows when you hit the brakes harder. It knows when you let up on the brakes slightly as you approach a traffic light. It knows exactly how hard you are pressing on the brake pedal at any moment and instantly adjusts the power to your brakes accordingly.
So, basically, I disagree with only one word in your post. You need to change the word “and” to “or” in your last sentence. “That voltage varies according to how hard you press down on the brake pedal or the rate of deceleration of the TV.” Prodigy and P3 don't know how hard you are pressing on the brake pedal and Brake Smart doesn't need to know the rate of deceleration.
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Sandy and Shirley,
You may be right, but I'm not so sure my last sentence was incorrect. The Prodigy and other like controllers DO vary the voltage according to how hard you press on the brake pedal. Pressing harder increases the rate of deceleration - hence more voltage to the brakes. I was however, responding to the post made by LarryJM and not the OP. He was questioning how a controller could tell how much voltage was getting to the brake magnets. As far as I know, the BrakeSmart varies and reports that voltage just as the others do. It just uses a different method of detecting how much voltage is necessary.
Barney
Well Barney, the differences are a bit subtle, but very important. The braking power required to create a certain level of deceleration will vary when going up or down a steep hill. It is not a huge difference, but there is a difference. Prodigy and P3 add an extra step to the equation. You press on the brake pedal, the tow vehicle begins to slow down, the controller senses the rate of slow down and adjusts the braking power based on the rate of slow down. Since the rate of slowdown varies on road conditions, hills, traction, etc, the amount of braking power will not exactly match your pedal pressure and you also have to wait till the tow vehicle reacts to the brakes being applied, admittedly a very short time delay.
Brake Smart reacts instantaneously to the pressure you exert on the brake pedal. It actually senses the pressure in the hydraulic brake line. If you apply more brake pressure to stop while going down hill, it senses that and applies more brake power to the RV brakes to match what you asked the tow vehicle to do.
Bottom line, the differences are subtle. Keeping your RV brakes instantly in perfect sync with the tow vehicle brakes is definitely a nice feature and it is a little better than what Prodigy does, but it costs 5 times as much to do it that way. Like I said, it is better, but nowhere near 5 times better. My comment about Prodigy vs. brake Smart has always been that Prodigy, and now P3, are the best bang for the buck. But, if you are willing to basically overpay for the very best, Brake Smart is the very best.
On Edit:
Barney,
While I was at lunch I was thinking of this thread and came up with an example, though rare, where the Brake Smart would perform better than the Prodigy.
It’s October and you decide to drive into the mountains to view the changing colors of the leaves. You leave on Sunday morning and are headed down the mountain. It is raining lightly and the roads are covered with leaves, not an unheard of situation. Or it is snowing lightly, less likely situation. Either way, you come to a panic stop situation and slam on the brakes. Due to the slippery conditions you lose traction and the tow vehicle start to slide. The Prodigy would recognize your “deceleration” as a gentle slow down because that is how the truck is stopping because of the skid and it would then gently apply the brakes to the RV. If you had a Brake Smart, it would sense the “high pressure” of the brake pedal on the hydraulic fluid and apply maximum braking power to the RV.
* This post was
edited 06/10/08 11:35am by Sandy & Shirley *
BarneyS wrote: Larry,
The newer brake controllers like the Prodigy, P3, Brakesmart, and others will tell you how much voltage is being supplied by the controller to the trailer brakes. That voltage varies according to how hard you press down on the brake pedal and the rate of deceleration of the TV.
Barney
So, basically, I disagree with only one word in your post. You need to change the word “and” to “or” in your last sentence. “That voltage varies according to how hard you press down on the brake pedal or the rate of deceleration of the TV.” Prodigy and P3 don't know how hard you are pressing on the brake pedal and Brake Smart doesn't need to know the rate of deceleration.
I dont see why Barney's statement is inaccurate. Redundant maybe, since pressing the brake pedal equals the rate of deceleration, but not inaccurate.
Sandy & Shirley wrote:
Barney,
While I was at lunch I was thinking of this thread and came up with an example, though rare, where the Brake Smart would perform better than the Prodigy.
It’s October and you decide to drive into the mountains to view the changing colors of the leaves. You leave on Sunday morning and are headed down the mountain. It is raining lightly and the roads are covered with leaves, not an unheard of situation. Or it is snowing lightly, less likely situation. Either way, you come to a panic stop situation and slam on the brakes. Due to the slippery conditions you lose traction and the tow vehicle start to slide. The Prodigy would recognize your “deceleration” as a gentle slow down because that is how the truck is stopping because of the skid and it would then gently apply the brakes to the RV. If you had a Brake Smart, it would sense the “high pressure” of the brake pedal on the hydraulic fluid and apply maximum braking power to the RV.
Interesting you would consider the Brakesmart an advantage here. I would consider the Prodigy a possible advantage here. Im using the MaxBrake (also uses a sensor in the brake line, just not as many 'extras' as the Brakesmart). I havent really done extensive wet weather testing but I can tell you threshold braking will be in order. Jamming the pedal and letting the trucks ABS sort it out will likely result in a jackknife as the trailer brakes will be at full power/skidding in a low traction situation. The Prodigy would 'sense' the lesser deceleration caused by the ABS and apply less power to the trailer, lessening the chance of a skid. Probably a moot point either way, but I would suggest threshold braking with either a MaxBrake or Brakesmart.
Well, just to add more to a long thread... I once asked a guy that drives one of those vans full of people up and down the Mt. Washington auto road in New Hampshire how often they change brake shoes on the vans since they must use the brakes a lot on the way down. His answer was simply, we don't use the brakes on the way down, we use the transmission. At that time they used Dodge vans with 360 engine and 4:11 rear end.
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Did you then ask him how often they had to swap out the transmission?
That is a road, no doubt, with a HUGE penalty for losing brakes (running off the edge).
Funny story about that road - when we drove up, I was a little concerned about the weight in my loaded pickup (we were tenting then). Every so often on the way up, I heard this sizzling sound coming from under the dash - I thought for sure I was frying something. I would stop at the emergency pull-offs and after a few minutes it would stop.
Long story short - eventually I figured out it was the pressure leaking out of a water bottle on the floorboard and not my truck burning up. It was a tense few miles
Dirk
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06 GMC Sierra 1500 Crew Cab, 5.3L V8, 3.42rear
05 30QBSS Trail-Cruiser, Prodigy BC, Reese Dual Cam W/D
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I was however, responding to the post made by LarryJM and not the OP. He was questioning how a controller could tell how much voltage was getting to the brake magnets. As far as I know, the BrakeSmart varies and reports that voltage just as the others do. It just uses a different method of detecting how much voltage is necessary.
