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Posted By Discussion Topic: sudden battery discharge? -- page: 1 2 3     supereal 10-02-2011 @ 5:23 AM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 Before you start swapping parts, put the leads of a voltmeter across each segment of the system with the power on. Any reading indicates loss in that part. Once you start to change parts, it is almost certain that you will have changed the problem, thinking it is fixed, only to have it happen again, probably at an inopportune time and place. As Henry put it, "diagnose, don't guess". This message was edited by supereal on 10-2-11 @ 5:24 AM fordmerc 10-01-2011 @ 1:42 PM reply profile send p.m. New Member Posts: 180 Joined: Oct 2009 A follow up note to all who have helped: TomO has solved my concern about the solenoid having continuity when battery is connected, but not when battery disconnected. The ignition switch was examined and tested on and off the car; it seems OK. There’s never been smoke. 3 solenoids do the same thing so that seems out, especially in view of TomO’s evidence. I’ve reached the conclusion that the engine shutoff and the sparking are 2 different problems: The engine shutoff may have been no gas in the tank!!! My plan is to isolate what seems to be a somewhat heat sensitive open circuit will be to isolate the various places that have been suggested as problem areas: brake switch and clock and anything else I can take out of the circuit; I can replace the current resistor with another. I feel I have eliminated the regulator cut out only because the problem has occurred with old and new voltage regulators . I have checked voltage at the coil and it is 3.4 V even when the short is present. I’ll let you all know when I have solved the problem, but it will take time because while it happens intermittently, I cannot reliably reproduce the problem. Thanks again for guidance. 37RAGTOPMAN 09-30-2011 @ 6:52 AM reply profile send p.m. Senior Posts: 1961 Joined: Oct 2009 ford merc try a different starter solinoid, and see if it makes a difference, in might not be completely shutting off,and might be feeding a certain amount of elect to the starter, not enough to make it turn over,but enough to drain the battery, I had this problem with a MODEL A one time, feel the starter to see if it is warm or hot, also feel the generator if it is warm, does anything have a smell to it ? my 3 cents, 37RAGTOPMAN unclemark 09-29-2011 @ 8:36 PM reply profile send p.m. Member Posts: 84 Joined: Dec 2009 I had a model T that did the exact same thing, it turned out to be the cut out on the generator, later in a different vehicle I had a similar problem resulting from a faulty regulator. Hope this helps a bit. TomO 09-26-2011 @ 11:20 AM reply profile send p.m. Senior Posts: 7253 Joined: Oct 2009 Fordmerc, You seem to be concerned about the continuity that you read across the solenoid. I went out to my car and checked out the continuity across the solenoid. I disconnected the ground cable from the battery and the ohm meter read 0 ohms. I suspected a ground loop, so I checked a spare starter. The meter reads continuity when it is connected from the starter lug to the case and a brush is on a commutator segment. I believe that this is what you are seeing. If a short is causing your car to stop, you should be able to smell smoke. Because you did not mention the smell, I am inclined to believe that you have an intermittent open circuit. The usual causes are loose connection at the ignition switch, resistor block and at the coil, a bad ignition switch or a bad resistor. The ignition switch is a brush that rides on a piece of Bakelite and makes contact with brass posts that the wires are connected to. After many years of wear, the Bakelite wears down and keeps the brush from making contact with the brass post. Tom fordmerc 09-25-2011 @ 6:44 PM reply profile send p.m. New Member Posts: 180 Joined: Oct 2009 I'm convinced the problem is electrical. I have not been able to cause the engine to stop as it did on the road. Battery discharge seems to occur after the car has been sitting most of the times it happened; I think it rapidly occurred only twice. Continuity across the solenoid measured with an ohmeter is same with and without power to batt side. Yes, I've tried the bigger hammer approach. Plan will be to start to try and find a short somewhere; I.e.,start over. biggest challenge is that the problem resolves spontaneously at an unpredictable rate. Dolman 09-25-2011 @ 1:06 PM reply profile send p.m. New Member Posts: 177 Joined: Dec 2010 Thanks for the reminder of the cranking amps (It's touted in every battery ad.) and the presence of reactance. Should of had the second cup of heart starter (pun intended). I'll accept the retroactive F now. supereal 09-25-2011 @ 11:59 AM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 When dealing with a coil, you have to know the impedance of the unit, as it involves both resistance (the copper loss) and the reactance of the windings. that means that without special equipment, the only test you can perform with a multimeter is resistance. The primary winding at 68 degrees F is .47 to .51 ohms, the secondary is 5800 ohms. Coils designed for 3.5 volts input will have lives shortened by higher inputs as the insulation and winding are heated. That is why the ignition resistor is used to provide a sort of voltage regulation. Anyone wishing to run coils at higher voltages, such as 12 volts, can have them specially wound for that purpose. As for the power demand of the starter, at maximum torque, 14 foot pounds, the current draw is 500 amperes. That is why the cables and connections must be correct. We check starter current with a clamp on meter, the only tool that can safely handle that level. TomO 09-25-2011 @ 11:29 AM reply profile send p.m. Senior Posts: 7253 Joined: Oct 2009 Fordmerc, You did not connect your meter leads correctly for the voltage drop test. One end should be connected to the stud with the cable going to the starter and the other end should be connected to the NEG battery post. With the starter engaged, the reading should be under 1 volt. You say that there is continuity between the battery terminal and the starter terminal on the solenoid, but no voltage present on the starter terminal. How are you measuring this? You should not be using an ohm meter on a circuit that has voltage applied to it, it will give you false readings. Because you have gas present after the engine stops, we are all assuming that the reason the engine stopped is electrical. The engine will keep running as long as the coil has enough voltage to provide a spark or the coil opens. You need to start like this is a new problem and try to isolate the sources of the problem. When the car dies, is the battery always dead? Have you checked for voltage at the coil when it dies and will not start? Have you tried vibrating the ignition switch, the resister board and the coil by tapping them with the insulated end of the screwdriver while the engine is running? Tom Dolman 09-25-2011 @ 7:46 AM reply profile send p.m. New Member Posts: 177 Joined: Dec 2010 Dr. Super, aside from fordmerc's problem, what is the effect on the longevity of the primary of the coil which is designed to see a nominal 3 volts and with the resistor bypassed, the coil then sees a nominal 6 volts? Keeping in mind that I have had only 1 cup of heart starter and I require 2 cups to fuel my brain, the resistor acts as a current limiter and with the engine running would drop 3 volts. The current through the primary would be 2 amps and dissipate 18 watts, ignoring the resistance of the coil, with the resistor jumped, the coil then drops 6 volts for a current of 6 amps and dissipates 36 watts. Considering Kirchoff's law, what is the current demand of the starter? I am clueless as to that value. If this discussion is inappropriate for this forum, if you have time, please PM me at amc@alaska.com

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