#76
IP: 199.173.226.236
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Probably would, but it doesn't do the same thing. A current limiter would vary the overall resistance up and down to keep the current at a set-point. They are made by combining a voltage regulator and a power transistor to keep a voltage drop though a sensing resistor constant. It was more a though-experiment than something I would actually build. It can also be done by using a voltage regulator followed by a ballast resistor set to precisely that voltage.
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#77
IP: 206.125.176.3
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Neil, just to throw a monkey wrench in the mix..my failed coil never got hotter than 135 F degrees. - I do not know if it got hotter than that when it wasn't failing.
I'll take some temp readings of the current set up & some more voltage readings for Kelly too. Didn't have time to run the motor yesterday, just a few extra minutes to turn the key on and grab some voltage numbers before heading home to cook dinner.
__________________
-Shawn "Holiday" - '89 Alura 35 #109 "Twice Around" - '77 C-30, #511 with original A-4 & MMI manifold - SOLD! (no longer a two boat owner!!) |
#78
IP: 24.152.131.220
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Picture time
Unfortunately my most accurate digital tester would not give meaningful voltage readings while the engine was running, they were jumping all over the place. My dumber tester that rounds voltage to the nearest integer works but the readings aren't precise at all. Oh well, here's what I have anyway:
Static unloaded battery voltage = 13.6 VDC Ignition on, engine not running = 12.5 VDC ahead of the resistor, 10.3 VDC at the coil post Resistances coil alone = 3.5 ohms coil + resistor = 4.3 ohms Here's the bracket. 3/4" x 3/4" aluminum angle Bracket and resistor View from the port side View from behind
__________________
Neil 1977 Catalina 30 San Pedro, California prior boats 1987 Westsail 32, 1970 Catalina 22 Had my hands in a few others Last edited by ndutton; 09-29-2011 at 11:33 AM. Reason: Added bracket picture |
#79
IP: 24.152.131.220
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Quote:
It reminds me of the advice on another thread from the alternator shop who cautioned against alt temps beyond 200F. Damage to the winding insulation was their reasoning.
__________________
Neil 1977 Catalina 30 San Pedro, California prior boats 1987 Westsail 32, 1970 Catalina 22 Had my hands in a few others |
#80
IP: 173.166.26.241
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Neil - Nice installation! The spiral lead, resistor to coil+ is a nice touch for a little extra resistance. BTW, regarding your digital meter fluctuations--do you have a suppressor in your alternator output circuit? They can cure a lot of fluctuation issues all over the system.
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#81
IP: 24.152.131.220
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Quote:
Quote:
__________________
Neil 1977 Catalina 30 San Pedro, California prior boats 1987 Westsail 32, 1970 Catalina 22 Had my hands in a few others |
#82
IP: 173.166.26.241
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Yes, that button head is a little substandard for you - not quite STRAK. As for suppressors, you might be pleasantly surprised how they help performance of sounders, autopilots, televisions etc. They are nothing but a big capacitor in the output circuit (actually interrupting alt + to batt+); also a big ground cable. As far as I know they can be had in 70 and 150 amp configurations.
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#83
IP: 148.170.241.1
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Quote:
Yeah, I didn't want to point that out and embarrass you, but now that you have - what the hell is up with that? Slacker.
__________________
- Bill T. - Richmond, VA Relentless pursuer of lost causes |
#84
IP: 24.152.131.220
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Re: polishing, presentation is everything. Really though, it's the little things that make a difference. If installing a track on deck, align the slots in the machine screw heads with the length of the track. If countersinking and plugging a piece of teak, try to align the holes. If making a new wood accessory that will be "finished bright", align the grain in the panels vertically even if it results in more offall (waste). It really makes a difference.
Okay, enough of that. Here's a graph of my coil temperature testing.
__________________
Neil 1977 Catalina 30 San Pedro, California prior boats 1987 Westsail 32, 1970 Catalina 22 Had my hands in a few others |
#85
IP: 75.68.130.228
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Its not stabilizing I would expect the temp to at one point level off and remain constant assuming nothing else changes
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#86
IP: 24.152.131.220
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I arbitrarily tested for only 30 minutes. As I use the boat I'll keep the temp gun handy. The rate of change (acceleration if you will) approaching the 30 minute mark was markedly different between the two. The no-resistor temp rose 10 degrees over the last 4 minutes while the with-resistor temp rose 2 degrees over the same final time interval. That's a 5:1 difference. Over the final 2 minutes the ratio was 4:1.
I think this implies the resistor setup was closer to reaching it's plateau than the no-resistor setup was. We'll see. I'll post more as I learn more. As it stands though, I'm a lot more comfortable at somewhere between 18% - 20% less coil heat even if it is at only the 30 minute mark. I'm careful not to suggest conclusions based on extrapolation. All I can say for now is 30 minute's worth.
__________________
Neil 1977 Catalina 30 San Pedro, California prior boats 1987 Westsail 32, 1970 Catalina 22 Had my hands in a few others Last edited by ndutton; 09-29-2011 at 07:13 PM. |
#87
IP: 99.88.90.212
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Another approach
I just returned from the boat after doing some "parallel" tests to Neil's.
To set the stage, I will say, at the outset, that my wiring condition is at the opposite end of the spectrum from Neil's. Most of my wiring looks to be over 30 years old and has been repaired numerous times. My approach to the tests was to try to find out just how low of a plug voltage an A4 would tolerate before performance would begin to drop. For the "doomsday" test I used an adjustable, ceramic resistor that would allow me to adjust down from my already low (11.6 volt) running coil voltage. For the record, my A4 cold starts very quickly despite this low voltage. After a brief warmup (about 5 minutes) I began adjusting the resistor down gradually and at just under 9 volts she began to stumble. At this voltage performance would certainly be affected and after shutting the engine down completely, it would not start at all, most likely because of the the additional starter induced voltage drop. After these tests, I installed a 2 ohm resistor (similar to Neil's) and despite now having a coil voltage of 10.2 volts, my engine started and ran the same as without the resistor. My coil temps were 120 degrees without a resistor and 105 degrees with the 2 ohm resistor, which seems to fall in line with Neil's findings. What is the reason for all of my testing?, simply to prove that many of us are quite likely "over volting" our ignition systems at the cost of early coil burnouts and shortened point or ignition module life. Tom |
#88
IP: 107.0.6.242
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Quote:
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#89
IP: 151.200.21.32
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Roger...temp gauge in hand the next time i run the engine. My wife loves it when we are motoring somewhere and I have my head in the engine compartment.
__________________
-Shawn "Holiday" - '89 Alura 35 #109 "Twice Around" - '77 C-30, #511 with original A-4 & MMI manifold - SOLD! (no longer a two boat owner!!) |
#90
IP: 99.88.90.212
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On the cool side
Shawn,
I have been taking my coil temp readings on the water pump side of the coil. First, on a Catalina 30, the access door makes taking that reading easy and secondly, the heat coming off of the exhaust has a tendancy to heat the port side of the coil up considerably more than the other side. Tom |
#91
IP: 24.152.131.220
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Reference the bottom picture in post #78
I took all my temp readings with the laser centered on the Flamethrower label.
__________________
Neil 1977 Catalina 30 San Pedro, California prior boats 1987 Westsail 32, 1970 Catalina 22 Had my hands in a few others |
#92
IP: 174.65.54.224
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New MMI catalogue item, "Dutton" coil resistor and mounting bracket!
With shipping and handling: $Priceless Sweet looking Neil. Thanks.
__________________
"Jim" S/V "Ahoi" 1967 Islander 29 Harbor Island, San Diego 2/7/67 A4 Engine Block date |
#93
IP: 193.253.220.149
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Coil+ vs. RPM graph
Oooooh, graphs!
Here's a go with my data. Sadly, I don't have temperature data. In parentheses I've calculated maximum amperage according to the formulas in this thread. My two resistors (0.22ohm x 2) are on the small side as I would like the maximum amperage to be a bit lower. In searching for a local solution, I struck out in the French auto parts stores, electric generator repair shop etc. and was forced to try electronic components. They look undersized to me and a bit fragile for my application...but at least I'm seeing the effects of added resistance before ordering a resistor from the U.S.
__________________
Kelly 1964 Cheoy Lee Bermuda Ketch, Wind and Atomic powered Last edited by Kelly; 09-30-2011 at 09:39 AM. |
#94
IP: 107.0.6.242
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Kelly - Your numbers are still a bit high even with the small resistors. If you are having trouble finding suitable resistors you can substitute 12 volt light bulbs. For ignition I'm guessing two 10 watt bulbs in parallel might give the right voltage. Better yet, order stock # 271-131 from Radio Shack (package of two, 1 ohm wirewound resistors).
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#95
IP: 193.253.220.149
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Hanley,
Hmmmm...thanks for the reference but I'm puzzled here. Shouldn't we be concerned by Watts in our application? When I look at the Radio-Shack product I see they label it as "10W" but it seems to be clearly marked with "2W" on the product picture. Which is true? And in our application, are we not likely to see values of near 50W (Volts x Amps = Watts; 12V * 4A = 48W) Feel free to correct me if I'm way off base here. The components I found locally are rated for 50W. Anyone want to jump in here to help clear things up??
__________________
Kelly 1964 Cheoy Lee Bermuda Ketch, Wind and Atomic powered |
#96
IP: 24.136.67.99
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Wow!
You guys amaze me with all the info you have compiled here, what a wealth of knowledge.
I think it may be time for a pole of sorts. There have to be more than a few like me who have had absolutely no trouble with the electronic ignition or the 'flame thrower" coils. It is obvious that some are having trouble and I just don't understand how it is problematic for so many. Perhaps a pole for both types and whether or not you are having trouble with your coils. I do have the Indigo and have used it for about 7~8 years now I think with absolutely no trouble. I have installed many pertronic units in dune buggies and had almost no trouble with them and seldom hear of anyone having trouble either. Is this problem a unit problem or a common issue found in OLD boats? This leads me to think wiring may be weak. There have to be many othere also having no trouble~~what say ya'? Heading out for Buccaneer Days at the Isthmus back tuesday. Dave Neptune |
#97
IP: 24.152.131.220
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Kelly,
You're in the neighborhood of 60 watts (rounded up) on the system so you'd best select a resistor capable of handling it. Dave, I have a response but late for work so I can't get into it now in any detail. The Cliff Notes version is wiring system condition and voltage drop are huge contributors and vary boat to boat. Shawn's the recent poster child for this one. Outta here
__________________
Neil 1977 Catalina 30 San Pedro, California prior boats 1987 Westsail 32, 1970 Catalina 22 Had my hands in a few others |
#98
IP: 193.253.220.149
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Just for the record, here's what I found locally (but at .22ohms). I could move up to a 100W version but they're not called the same thing: "charge resistor" in a direct translation.
__________________
Kelly 1964 Cheoy Lee Bermuda Ketch, Wind and Atomic powered |
#99
IP: 208.89.140.11
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I think what happened is the pertronix design doesn't take into account the change of alternator voltage from 13.5 to 14.2. This is an automotive product we are using in a marine environment.
Steve |
#100
IP: 107.0.6.243
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Kelly - Somebody put the wrong picture out. Here is what comes out of the package.
Last edited by hanleyclifford; 07-13-2016 at 08:32 PM. |
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