Voltage Reduction System - Convertible Hydraulics
#81
10-22-2010, 06:12 AM
Kevin,
Just wanted to be sure no misimpressions are left here re: battery load.
Raising or lowering the top draws an average current on the order of 12 amps for 30 seconds (actually less, but let's be conservative). Crunch a couple of numbers and we see that this is about 0.1 amp-hours. So, for a 100 amp-hour battery, we have extracted ~ 0.1 % of its charge. By way of comparison, we would extract more by playing the stereo while washing the car.
Jaguar does not recommend running engine-off, nor installing voltage reduction, nor installing a relief valve. It's because of what happens when we follow that path that we're having all of these discussions.
Best,
Just wanted to be sure no misimpressions are left here re: battery load.
Raising or lowering the top draws an average current on the order of 12 amps for 30 seconds (actually less, but let's be conservative). Crunch a couple of numbers and we see that this is about 0.1 amp-hours. So, for a 100 amp-hour battery, we have extracted ~ 0.1 % of its charge. By way of comparison, we would extract more by playing the stereo while washing the car.
Jaguar does not recommend running engine-off, nor installing voltage reduction, nor installing a relief valve. It's because of what happens when we follow that path that we're having all of these discussions.
Best,
#82
10-22-2010, 07:21 AM
Veteran Member
#83
10-22-2010, 07:58 AM
#84
10-22-2010, 10:28 AM
Veteran member
Gus is right and glad he jumped in here before it continued further. Let's just accept the fact that there are different ways to pursue the pressure issue in the lines...one by an electrical approach, the other by mechanical means.
Until we know what Kevin's issue is, lets not assume its the resistor.
Dennis, you can crunch numbers all day long (as I do for a living) and use it as a basis for justification, but you also must keep in mind there are other variables that may and can contribute to kevin running out of juice during his top op cycle. He could have a lower starting voltage, he could have poor conductance thru grounds and wiring (i'm an engineer, but not an electrical one) we will not know more unless he puts a voltage meter and measures the value during the process.
Doug was exaggerating I believe, cycling the roof once or twice w/o the engine running just seems like a lot of energy draw, and after doing so...if the battery was weak in the first place, may not allow the car to start? Anyway, it read to me just an attempt to remind everyone that we should all consider the priorities of the car's systems when incorporating relatively new operational processes and what it may affect, and to what degree.
There are pros and cons for each option for this pressure reducing goal. I have my opinion as to which one I will implement. I could explain my reasons for doing so, but the most important one is what I am most confident in installing, after weighing the advantages and disadvantages presented.
Just like which weight of oil and dino vs synth debate, so we will now put this comparison into the 'flammable' and very opinionated ranks. Of which, as of now, should be addressed delicately under moderator watch.
Until we know what Kevin's issue is, lets not assume its the resistor.
Dennis, you can crunch numbers all day long (as I do for a living) and use it as a basis for justification, but you also must keep in mind there are other variables that may and can contribute to kevin running out of juice during his top op cycle. He could have a lower starting voltage, he could have poor conductance thru grounds and wiring (i'm an engineer, but not an electrical one) we will not know more unless he puts a voltage meter and measures the value during the process.
Doug was exaggerating I believe, cycling the roof once or twice w/o the engine running just seems like a lot of energy draw, and after doing so...if the battery was weak in the first place, may not allow the car to start? Anyway, it read to me just an attempt to remind everyone that we should all consider the priorities of the car's systems when incorporating relatively new operational processes and what it may affect, and to what degree.
There are pros and cons for each option for this pressure reducing goal. I have my opinion as to which one I will implement. I could explain my reasons for doing so, but the most important one is what I am most confident in installing, after weighing the advantages and disadvantages presented.
Just like which weight of oil and dino vs synth debate, so we will now put this comparison into the 'flammable' and very opinionated ranks. Of which, as of now, should be addressed delicately under moderator watch.
#85
10-22-2010, 10:31 AM
Veteran Member
I did not mean to take a "dig" at anyone else and really could care less about which "solution" is chosen for addressing the convertible top issue. My SOLE misgiving is doing anything at all that tinkers with the obviously touchy electrical systems of these cars. Aside from the Nikasil issue and the tensioner issue, I think you will find the most posts of problems at this and other forums will typically have something to do with wacky behavior of the electrical system. Moreover, more likely than not, the solution of those problems will be related to the battery. This was also pointed out when I brought the car to the dealer for a few problems and the service guy told me how sensitive the various electrical network systems were to battery condition. I hope you guys don't "Juan Williams" me for just wanting to discuss all of the pluses and minuses.
Doug
Doug
#86
10-22-2010, 10:56 AM
#87
10-22-2010, 11:14 AM
H20boy,
Kevin and I were, and are, doing just fine. Neither he nor I thinks at this point that the resistor is the problem (as least I believe that's his view). If you'll take a pass back through the thread I think you'll see that this is so.
My numbers exercise was simply to show that the assertion (which did not come from Kevin) that the voltage reduction system will "wear the hell out of your battery" is demonstrably untrue. This in not "an exageration"; it is totally untethered to the real numbers which show the battery load to be quite small. If the keepers-of-the-keys here feel that such a wrong assertion should be left unchallenged, I'm at a loss to understand that.
I think you will find I have never said anything other that that both approaches are valid. You never have, and never will, hear anything from me remotely like "wear the hell out ..." discussing someone else's work.
But if I'm to participate here, I won't let go unchallanged things posted about this system which are just plain wrong, and so mislead or confuse people. If that doesn't work for you, so be it.
Kevin and I were, and are, doing just fine. Neither he nor I thinks at this point that the resistor is the problem (as least I believe that's his view). If you'll take a pass back through the thread I think you'll see that this is so.
My numbers exercise was simply to show that the assertion (which did not come from Kevin) that the voltage reduction system will "wear the hell out of your battery" is demonstrably untrue. This in not "an exageration"; it is totally untethered to the real numbers which show the battery load to be quite small. If the keepers-of-the-keys here feel that such a wrong assertion should be left unchallenged, I'm at a loss to understand that.
I think you will find I have never said anything other that that both approaches are valid. You never have, and never will, hear anything from me remotely like "wear the hell out ..." discussing someone else's work.
But if I'm to participate here, I won't let go unchallanged things posted about this system which are just plain wrong, and so mislead or confuse people. If that doesn't work for you, so be it.
#88
10-22-2010, 11:27 AM
Veteran Member
I remember the good old days when you would get a lot of advance warning when a battery was going low in a car. Even then it used to be easy to squeeze one more start or two just before the battery totally died by knocking on the battery post or jiggling the terminal. With more modern cars I have owned (by modern I mean since the 1990s or so), I notice there is almost NO warning when a battery is going south. The car will start just fine going to work or going on an errand and a few minutes/hours later all you get is a click. I think the modern electrical systems are just much more sensitive to battery voltage so you end up not being able to crank at all once the system senses voltage is below some acceptable level. It is really for that reason alone that I have gotten in the habit of avoiding operating anything electrical without the engine running for fear that I could be at that voltage threshold. So of course I wait to turn headlights on until after starting. Ditto for operating windows, adjusting seats, turning on heaters/air conditioning, etc. I guess the "warning" you get with the Jaguar system is quirky warning messages, front windows that do not assume the correct position when opening/closing the doors, etc. Doug
#89
10-22-2010, 11:57 AM
Veteran member
But if I'm to participate here, I won't let go unchallanged things posted about this system which are just plain wrong, and so mislead or confuse people. If that doesn't work for you, so be it.
Answering questions, averting confusion and preventing misleading ideas and opinions will be much more difficult with this resistor approach, than it is in the relief valve. You see that, right? Electricity and the principles on which it is used isn't as easily understood, nor taught, to most people as the simplicit nature and function of the mechanical valve. I have no doubt you can adequately handle, as you have so far, to keep the facts visible and the uncertainty and doubt tamed as best you can.
Sometimes its all in how you respond to comment of unknown intention. In response to the 'wear the hell out' comment, I would have said something along the lines of "with a good battery, and no other systems on - headlamps, climate control fans, stereo, interior lights (as I have most on when turning the key to the 'on' position), and cycling the top one time' shouldn't draw enough to cause battery wear, if you mean excessive voltage drop by the term 'wear' " I often see the worse case scenario in everything, as is my vocation, and perhaps doug does also when the 'engine off' procedure is used, and which you do promote, correct? See, initially, that makes me think all sorts of consequences, when the top's system seems like a huge electrical requirement.
Such as this question you may be able to help me understand. Lets say Kevin's issue is more frequent. Let's say you hold the button down during the stall hoping to overcome that peak and think it'll close...just give it a second or two...will something happen to the motor in its attempt to continue closing? Will that 'stall' draw more amps from the battery and drain it quicker than a successfully operating top?
Anyway, my point was to only remind everyone of the etiquette and there nobody is targeted for oblivion based on the last few posts.
Everyone proceed, and I apologize for the rambling. Must be the friday getting to me.
Last edited by H20boy; 10-22-2010 at 12:08 PM. Reason: added more stuff
#90
10-22-2010, 12:26 PM
Veteran Member
Hey Matt--I guess that explains it. We are both engineers (you civil and me structural/earthquake)!
Doug
#91
10-22-2010, 03:30 PM
H20boy,
Well, on this issue of diplomatic writing, I suppose we could all (as in all) stand some improvement. Along the same lines, it could be that what catches your eye as potentially inflammatory -- and what does not -- might too be worth a little reflection.
Technical stuff ...
"... when the 'engine off' procedure is used, and which you do promote, correct? See, initially, that makes me think all sorts of consequences, when the top's system seems like a huge electrical requirement."
Engine-off? I believe we should be running these convertible tops at the lowest peak pressure consistent with reliable function. If everything works OK engine-off I would run that way, because engine-on produces ~ 150 PSI more peak pressure (this does not apply with relief valve). That's when and why I like engine-off.
Is it a "huge electrical requirement"? In my post this morning I ran through the actual numbers to show that it is some 0.1% of the battery charge. I don't know how better to show that it is a very small load indeed. But let me know if something there still troubles you.
"Lets say Kevin's issue is more frequent. Let's say you hold the button down during the stall hoping to overcome that peak and think it'll close...just give it a second or two...will something happen to the motor in its attempt to continue closing? Will that 'stall' draw more amps from the battery and drain it quicker than a successfully operating top?"
First off, we should NOT run the system this way repeatedly; the peak pressure is right at the edge, and can barely close the latch. Remedies were discussed most recently here: https://www.jaguarforums.com/forum/s...5&postcount=65
What is happening is not a motor stall but a "dead-head" condition: the pump and motor are turning, but there's not enough pressure to close the latch. All the energy goes into heat, so we don't want to hold that button down for more than a few seconds with nothing moving. Without dragging out all the graphs and stuff, let me just say that releasing and again pushing the button might close the latch (since the motor makes its peak torque at zero rpm) and that the current will go up a bit in such a case vs. a "normal" latch closure.
Much of this is old ground for those of us who have rolled around in this stuff in prior posts.
Well, on this issue of diplomatic writing, I suppose we could all (as in all) stand some improvement. Along the same lines, it could be that what catches your eye as potentially inflammatory -- and what does not -- might too be worth a little reflection.
Technical stuff ...
"... when the 'engine off' procedure is used, and which you do promote, correct? See, initially, that makes me think all sorts of consequences, when the top's system seems like a huge electrical requirement."
Engine-off? I believe we should be running these convertible tops at the lowest peak pressure consistent with reliable function. If everything works OK engine-off I would run that way, because engine-on produces ~ 150 PSI more peak pressure (this does not apply with relief valve). That's when and why I like engine-off.
Is it a "huge electrical requirement"? In my post this morning I ran through the actual numbers to show that it is some 0.1% of the battery charge. I don't know how better to show that it is a very small load indeed. But let me know if something there still troubles you.
"Lets say Kevin's issue is more frequent. Let's say you hold the button down during the stall hoping to overcome that peak and think it'll close...just give it a second or two...will something happen to the motor in its attempt to continue closing? Will that 'stall' draw more amps from the battery and drain it quicker than a successfully operating top?"
First off, we should NOT run the system this way repeatedly; the peak pressure is right at the edge, and can barely close the latch. Remedies were discussed most recently here: https://www.jaguarforums.com/forum/s...5&postcount=65
What is happening is not a motor stall but a "dead-head" condition: the pump and motor are turning, but there's not enough pressure to close the latch. All the energy goes into heat, so we don't want to hold that button down for more than a few seconds with nothing moving. Without dragging out all the graphs and stuff, let me just say that releasing and again pushing the button might close the latch (since the motor makes its peak torque at zero rpm) and that the current will go up a bit in such a case vs. a "normal" latch closure.
Much of this is old ground for those of us who have rolled around in this stuff in prior posts.
#92
10-22-2010, 05:04 PM
Veteran Member
Hey Dennis,
I was wondering if you had a handle on how much juice goes into raising and lowering the roof versus having headlights on. I do not know much about electrical engineering but for some reason, my gut feel is that working the top takes more power than having the headlights on.
In my last car, I could get a gut feel for how much power something drew by watching the voltmeter with the car running while operating the device. For example, it always surprised me that the voltmeter needle would take a pretty large dive when turning on the rear window defroster and also when raising a power window and keeping my finger on the button too long, but not take that much of a dive from turning on the headlights.
The reason I ask is that I have had cars with weak batteries that would just barely start if nothing was on but would NOT start if the headlights were on--that bit of current draw from the headlights was just enough to prevent starting. So using the headlight draw as some pseudo-baseline, how much does operating the top draw from the battery (e.g., 25% less, 50% more, 100% more?). My intuition is that it draws more but you are saying the draw is pretty incremental.
Thanks,
Doug
I was wondering if you had a handle on how much juice goes into raising and lowering the roof versus having headlights on. I do not know much about electrical engineering but for some reason, my gut feel is that working the top takes more power than having the headlights on.
In my last car, I could get a gut feel for how much power something drew by watching the voltmeter with the car running while operating the device. For example, it always surprised me that the voltmeter needle would take a pretty large dive when turning on the rear window defroster and also when raising a power window and keeping my finger on the button too long, but not take that much of a dive from turning on the headlights.
The reason I ask is that I have had cars with weak batteries that would just barely start if nothing was on but would NOT start if the headlights were on--that bit of current draw from the headlights was just enough to prevent starting. So using the headlight draw as some pseudo-baseline, how much does operating the top draw from the battery (e.g., 25% less, 50% more, 100% more?). My intuition is that it draws more but you are saying the draw is pretty incremental.
Thanks,
Doug
#93
10-22-2010, 07:51 PM
Veteran member
I appreciate the additional explanation Dennis, thank you. And yes, I have not rolled around the entire thread as much of a participant in the subject but with my moderator hat on instead... so I may have easily missed some of the content that would have answered my last questions. Sorry about that.
#94
10-23-2010, 07:53 AM
If we're back above water again on this thread, I just want to say I have had my resistor in now for a week/10 days, something like that. Everything is working as I've hoped.
I have one customer who has been chomping at the bit to get one installed in his XKR. I'll do that first of next week. I'll have a couple more data points out there now, but eventually more as other customers will use it too.
I have one customer who has been chomping at the bit to get one installed in his XKR. I'll do that first of next week. I'll have a couple more data points out there now, but eventually more as other customers will use it too.
#95
10-27-2010, 07:51 AM
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I am new here and still considering either the hydraulic or the electric solution. As an electrical engineer, I do find some appeal in the electrical solution, and of course I'm thinking of ways to improve it. Ha!!! :-)
I cannot contribute much to the hydraulic one since it is not my domain and it also seems beautifully researched and implemented.
Back to the electrical solution for now... Instead of making your own connections to the Jaguar circuitry, did you consider getting a pair of identical connectors and plugging them in series with the existing connectors? I looked at mine and the connectors are AMP 926474. A quick web search revealed that the new equivalent seems to be AMP 180907. Mouser.com has them available for $.30 each plus about $7 for shipping!! They may be cheaper elsewhere, but the shipping is the killer anyway.
Go to mouser.com and search for p/n 180907.
In my opinion, using the AMP connectors would make the design even more elegant and secure. There will be no splicing of wires, the connections would be as secure as the factory's, it would be trivial to remove or add the resistor and it would look more "stock" versus home-made.
Thoughts?
I cannot contribute much to the hydraulic one since it is not my domain and it also seems beautifully researched and implemented.
Back to the electrical solution for now... Instead of making your own connections to the Jaguar circuitry, did you consider getting a pair of identical connectors and plugging them in series with the existing connectors? I looked at mine and the connectors are AMP 926474. A quick web search revealed that the new equivalent seems to be AMP 180907. Mouser.com has them available for $.30 each plus about $7 for shipping!! They may be cheaper elsewhere, but the shipping is the killer anyway.
Go to mouser.com and search for p/n 180907.
In my opinion, using the AMP connectors would make the design even more elegant and secure. There will be no splicing of wires, the connections would be as secure as the factory's, it would be trivial to remove or add the resistor and it would look more "stock" versus home-made.
Thoughts?
#96
10-27-2010, 08:33 AM
That is a very good idea. I'd like to see it done. I've already installed my own by splicing and using the spade connectors so I can reverse using some heat shrink tubing if I choose, but going forward on customers' cars, it would be a more elegant installation. Glad to have you weighing in, BTW.
#97
10-27-2010, 08:48 AM
Sailrboy,
Your idea on connectors works for me. There is also a method, along the lines you suggested, contributed by test_point. You'll see it in the final section of the latest PDF available here ...
http://www.scorekeeper.com/jaguar/jaguar02.htm
(I'm guessing that you may have seen only the first PDF. That one did not show the improved installation, only my crude initial method.)
Best,
Your idea on connectors works for me. There is also a method, along the lines you suggested, contributed by test_point. You'll see it in the final section of the latest PDF available here ...
http://www.scorekeeper.com/jaguar/jaguar02.htm
(I'm guessing that you may have seen only the first PDF. That one did not show the improved installation, only my crude initial method.)
Best,
Last edited by Dennis07; 03-10-2011 at 08:23 AM. Reason: updating location to download latest PDF
#98
10-27-2010, 03:39 PM
Dennis
Just an update on the resistor that I added several weeks ago. Since the weather is getting better to have the top down here in Florida I have operated it on numerous occasions and as I said on the other forum, other that adding a few seconds to the cycle time all is well.. Again thanks for your efforts.
Just an update on the resistor that I added several weeks ago. Since the weather is getting better to have the top down here in Florida I have operated it on numerous occasions and as I said on the other forum, other that adding a few seconds to the cycle time all is well.. Again thanks for your efforts.
#99
10-27-2010, 04:25 PM
#100
10-27-2010, 04:33 PM
Veteran Member
Failure to Latch
I just experienced my first 'failure to latch' after installing the resistor and through 30 cycles of the top. Since I believe that lower voltage results in lower hydraulic pressure I have been operating the top in 'engine off' mode. In all fairness, the car had not been driven in 5 days.
Releasing the 'up' switch and operating it again closed the latch and all was fine. I have not been able to duplicate the failure.
I got out the old VOM and the battery read 12.36v at rest, a little low from an expected 12.6v. While connecting the VOM I discovered a cold solder joint on the resistor as it broke off. After re soldering and connected to the load side of the resistor it read 9.57v during down operation with a momentary dip to a low reading of 7.5v at the end of the cycle. The up operation, surprisingly since I expected higher current draw, read almost exactly the same, with the spike/dip to about 7.5v at latch closing.
Guess I will clean/lube the latch mechanism as it has been reported as a problem even without a reduced pressure system in place and see what happens. I am sure that my latch has never been addressed before. Perhaps we are operating at the ragged and unmanaged edge of the performance capability of the resistor solution at 0.20 ohms, especially in the 'engine off' mode.
Anyone that experiences a 'failure to latch' or any other malfunction of the resistor solution please let us know via a post.
Releasing the 'up' switch and operating it again closed the latch and all was fine. I have not been able to duplicate the failure.
I got out the old VOM and the battery read 12.36v at rest, a little low from an expected 12.6v. While connecting the VOM I discovered a cold solder joint on the resistor as it broke off. After re soldering and connected to the load side of the resistor it read 9.57v during down operation with a momentary dip to a low reading of 7.5v at the end of the cycle. The up operation, surprisingly since I expected higher current draw, read almost exactly the same, with the spike/dip to about 7.5v at latch closing.
Guess I will clean/lube the latch mechanism as it has been reported as a problem even without a reduced pressure system in place and see what happens. I am sure that my latch has never been addressed before. Perhaps we are operating at the ragged and unmanaged edge of the performance capability of the resistor solution at 0.20 ohms, especially in the 'engine off' mode.
Anyone that experiences a 'failure to latch' or any other malfunction of the resistor solution please let us know via a post.