raydurr Posted June 7, 2016 Share Posted June 7, 2016 I have been having headlamp bulbs burn out for sometime. I have 21 CP installed now, which have burned out. I have lost no other bulbs. I have checked my charging system output with a voltage meter. It shows 7.6 volts as a maximum reading with engine revved up. What should the maximum permissible voltage be? Link to comment Share on other sites More sharing options...
27donb Posted June 7, 2016 Share Posted June 7, 2016 I thought bulbs of that kind were rated 6-8 volts. Maybe they are burning out because you are close to the limit on your voltage reading. Link to comment Share on other sites More sharing options...
Larry Schramm Posted June 9, 2016 Share Posted June 9, 2016 IMO, 7.6 volts should not be too high unless there is a spike in the voltage. Link to comment Share on other sites More sharing options...
DonMicheletti Posted June 10, 2016 Share Posted June 10, 2016 A long shot is that cruddy battery terminals are letting the generator spike from time to time. But I agree, the 7.6 volts shouldnt be a problem Link to comment Share on other sites More sharing options...
Larry Schramm Posted June 10, 2016 Share Posted June 10, 2016 10 hours ago, DonMicheletti said: A long shot is that cruddy battery terminals are letting the generator spike from time to time. But I agree, the 7.6 volts shouldnt be a problem Agree. Check all connections at the battery and generator. Might be a bad internal connection in the generator? Link to comment Share on other sites More sharing options...
Thriller Posted June 12, 2016 Share Posted June 12, 2016 Harder to measure, but many components will fail due to excess current. A short in the circuit could be at fault. Link to comment Share on other sites More sharing options...
raydurr Posted June 14, 2016 Author Share Posted June 14, 2016 All wiring has been replaced. Battery connection is clean and tight. Generator output appears to be steady according to the ammeter . Headlamp switch has been reconditioned. No electrical gremlins whatsoever other than the headlamps bulbs failing. Link to comment Share on other sites More sharing options...
Guest Posted June 14, 2016 Share Posted June 14, 2016 Could be offshore bulbs or vibration. Vibration will cause a bulb to fail almost as quick as too much voltage. Link to comment Share on other sites More sharing options...
AzBob Posted June 14, 2016 Share Posted June 14, 2016 (edited) Ray, Don't know for sure if your '29 headlamps is wired like my '26, (Positive wires to the socket bulb terminals and is grounded through the socket shell to the headlamp bucket to the lamp crossbar). I was not getting a good ground due to paint rust, etc. I installed separate ground wires connecting each bulb socket direct to a point on the frame. Works great. Edited June 14, 2016 by AzBob spelling correction (see edit history) Link to comment Share on other sites More sharing options...
Morgan Wright Posted June 14, 2016 Share Posted June 14, 2016 50 minutes ago, AzBob said: Ray, Don't no for sure if your '29 headlamps is wired like my '26, (Positive wires to the socket bulb terminals and is grounded through the socket shell to the headlamp bucket to the lamp crossbar). I was not getting a good ground due to paint rust, etc. I installed a separate ground wires connecting each bulb socket direct to a point on the frame. Works great. What I did was remove and disassemble all light fixtures and soak them in vinegar for 2 hours. It removes all rust, it comes off with a toothbrush right down to the bare metal. Vinegar is AMAZING at removing rust, Link to comment Share on other sites More sharing options...
raydurr Posted June 14, 2016 Author Share Posted June 14, 2016 2 hours ago, Tinindian said: Could be offshore bulbs or vibration. Vibration will cause a bulb to fail almost as quick as too much voltage. American made , NORS bulbs from different sources. Link to comment Share on other sites More sharing options...
raydurr Posted June 14, 2016 Author Share Posted June 14, 2016 1 hour ago, AzBob said: Ray, Don't no for sure if your '29 headlamps is wired like my '26, (Positive wires to the socket bulb terminals and is grounded through the socket shell to the headlamp bucket to the lamp crossbar). I was not getting a good ground due to paint rust, etc. I installed a separate ground wires connecting each bulb socket direct to a point on the frame. Works great. My headlamp plug configurations sounds to be the same as yours. All parts were stripped . Parts were masked to ensure good connection once reassembled. Power supply to bulbs appears to be strong and even. Bulbs usually fail when driving. No vibrations or adverse road conditions. Link to comment Share on other sites More sharing options...
DonMicheletti Posted June 14, 2016 Share Posted June 14, 2016 Everything seems to point to voltage spikes. The ammeter only indicates current not voltage. I have no idea how you could check it. If there are just spikes, "catching it in the act" could be difficult. Link to comment Share on other sites More sharing options...
hidden_hunter Posted June 14, 2016 Share Posted June 14, 2016 We found it much easier to diagnose what was going on with the electrical system by using an analogue multimeter, couldn't get a great reading with the digital multimeter Link to comment Share on other sites More sharing options...
Larry Schramm Posted June 14, 2016 Share Posted June 14, 2016 If you get a good Fluke DVOM meter (not cheap) it has a record function that can record both min & max voltage. Here is one that will do a min/max record. http://www.myflukestore.com/p6050/fluke_113.php Link to comment Share on other sites More sharing options...
FLYER15015 Posted June 15, 2016 Share Posted June 15, 2016 Just as a low cost test, could you install 12 volt bulbs and run them for awhile ? If THEY blow, it would indicate to me a dead short. Link to comment Share on other sites More sharing options...
Larry Schramm Posted June 16, 2016 Share Posted June 16, 2016 23 hours ago, FLYER15015 said: Just as a low cost test, could you install 12 volt bulbs and run them for awhile ? If THEY blow, it would indicate to me a dead short. ?? How does that work electrically?? A 12 volt bulb vs a 6 volt bulb is that the 12 volt bulb is a larger resistor? To make a bulb light one side is run to ground and the other side goes to voltage. Shorting the ground wire to ground does nothing. Grounding the power side wire would burn something up stream of the bulb. At least that is the way I was taught and understand the electrical system?? Link to comment Share on other sites More sharing options...
FLYER15015 Posted June 17, 2016 Share Posted June 17, 2016 In "raydurr's first post, he stated that in his 6 volt system he was getting 7.6 volts as his max generator output. Maybe the 6 volt bulbs don't have the capacity to absorb that extra 1.6 volts ? A 12 volt light bulb certainly can handle 7.6 volts. Won't be a bright as they should, but if they DO blow, then we'll know there is something else going on in that circuit. Mike in Colorado Link to comment Share on other sites More sharing options...
Larry Schramm Posted June 18, 2016 Share Posted June 18, 2016 12 Volt systems are designed to operate up to a peak of 16 volts without damaging components in the system. Normal operating voltage output of the generator on a 12 volt system is usually about 13.0 - 14.5 volts depending upon the state of charge of the battery and what accessories and lights, etc are on at any one time. 7.6 volt max output should not be a problem. Might just be on the higher side of "normal" but should be fine. Just IMO. The best course of action would be to get a meter that can record the minimum and maximum voltage in the system while driving and running. Anything else is just throwing parts at the issue and not fixing the root cause. Link to comment Share on other sites More sharing options...
Mark Shaw Posted June 18, 2016 Share Posted June 18, 2016 NOS bulbs have a shorter life span. You might just try buying some new bulbs to see if they last longer... Link to comment Share on other sites More sharing options...
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