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question about shorts/grounding

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19_again

19_again

Jedi Warrior
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Hard to believe, but I have an electrical problem. When I use my lights, my ignition light comes on regardless of rpms. I'm postive ground, have reversed polarity on my generator. I think I can drive the car for days without using lights and my battery will be fine. But using lights for 30 minutes will kill the battery. The car will run until I shut it off, but will barely turn over when I try to start it, eventually not cranking at all. DPO had hand wound the wires to the headlights at a break point (as opposed to solder, crimp, or even tape). Since I have new harness on order, I just coated the joint with dielectric grease and taped it up good. As expected when I first start the car, after releasing choke I'll see the ignition light for a few seconds until rpms even out. After the battery died last time, I reversed the polarity on the generator again per instructions forwarded by Jack. Tonight it happened again after 30 minutes of lights on. New Generator/ new battery 1 month/new battery cables.
Any ideas?
 
Have you checked your regulator? They are adjustable, make sure you check voltage while adjusting.
 
Hello 19,

firstly the positive or negative earth set up is irrelevant to your problem. It is basically load versus output, so either the load is too much for the system or the system is below par. It could be the regulator, it shouldn't be the drive belt if you have fitted a new generator?. Have the headlights got some very high power lamps in them or do you have some auxiliary lights fitted?

Alec
 
Don't know if this is relevant but I kept having my battery go low every time I took the car out. Finally I paid attention to the voltmeter I had installed last year. Every time I stepped on the brakes voltage dropped to zero!

It took hours but we found the dead short and repaired the circuit. No more dead-dying battery!

Guinn
 
No auxiliary lights, standard lamps. I felt pos/neg would be in issue given generators being neg ground by default. Haven't checked voltage regulator but fuse box is new. Belt is fine, 3/4 inch movement as recommended here. No volt meter installed, YET! Haven't checked output on genny yet, assumed it was good being new. I know I know. Next step will be to start car, and as lights are turned on watch the ignition light.
 
"I'm postive ground, have reversed polarity on my generator. "

I'm confused... normally the older LBCs are/were positive ground and owners switched them to negative ground by re-polarizing the generator... to negative earth. So which is your car? Positive earth with a new-ish generator polarized for that earth?

The volt meter will help you find this problem. However, I don't like the Smiths ones because they are bimetallic and respond slowly which can hide changes that happen quickly. Consider a VDO or AutoMeter gauge (always available used on eBay) or temporarily driving around with your volt/ohm meter hooked up to the car's wiring. If you don't have a volt/ohm meter, this is a great excuse to buy one. Even the cheap $3 ones from Harbor Freight are good investments.
 
Doug,
The car is positive earth, but as I re-read the instructions I see that I have described my actions incorrectly. I changed the polarity on the voltage regulator not the genny. Jack Laird, (it's all his fault) was kind enough to forward an article by Mike Martinez detailing how to do this. It was explained that the genny will charge either way, but VR's only have one polarity. I do have an analog voltmeter and have checked the output on the genny and it's fine. It's possible at this point that I reversed polarity on a previously (by PO)reversed VR. OY! Are you aware of a method to determine the current (pun intended) polarity of the VR?
 
Some of the instructions I've read describe re-polarizing the generator using steps at the voltage regulator. Regardless of where the steps are taken, you are in fact re-polarizing the field coils of the generator. The regulator is just a bunch of points and electro-magnets and will work with either polarity.

I have never been good at adjusting the voltage regulators. The steps are detailed well enough in the manuals but I have not been able to do them correctly. You might want to consider either adjusting or replacing your regulator since the generator is new. However, if you fit a new regulator, make sure you degrease the relay contacts inside before placing it in service. The new ones are shipped with a protectant on the points that must be removed.

Before investing in a new regulator you may want to take the generator (even though it's new) to an electric shop and have it tested. I would not use the test services at the auto parts store. They may be OK testing alternators but I remember years ago having a generator from an MGB tested and was told it was fine... only to find out much later that it was toast. A full time auto electric shop did a more complete test and determined the field coils were shorted.
 
Bah, those wires all go to places. The instructions repolizared the genny without you haveing to dig for wires. The regulator can not be polarized, it just is.
 
Thank God for small favors. Thanks Doug and Jack. My harness shipped today, I may be near the end of this mystery after all.
Mike
 
Well I've been on the road for a week. Didn't have time to check regulator before I left. Tonite when I got home, I checked the old girl, she was fine so I went out to the garage and checked on my baby. When she's idling, the ignition light is not on. When I rev her up, the ignition comes on. 3500 rpm the ignition light is on, 800 rpm no ignition light. I hate idiot lights, but this time I gotta wonder. Why is tis happening? Belt is tight enough, not too tight.
 
The light will also come on if the generator is putting out too much voltage. (bad regulator) Check things with a volt meter.
D
 
Hi 19_ again, Like Dave says check the components with a voltmeter. However, 800 RPM is a bit low for most Healey generator regulators to pick up. The stock Healey is notorious for not charging at idle speed-Light On. Check very carefully with a tach and see if it does not go out around 900 or 950 RPM if it does it is probably OK if the battery stays charged.---Fwiw--Keoke
 
But his light comes on when the engine revs up. Bad bad regulator. Just replace the darn thing, not worth messing with.
 
Jack, thanks.
You know after reading the Bentley book to see how to adjust/check the voltage regulator I figured I'd bring her down to the electrical shop and let them have at it. But your comment lead me to look up pricing, shoot you're right, just replace the dam thing.
 
HI 19 Again, One note here. just buying a new control box does not guarantee that it will not have to be adjusted on the car. This is because specific calibrated units are not supplied anymore . The regulators are classified by Amperage output of the generator and given application batch numbers.--Fwiw--Keoke
 
One last question. Can I drive the car with this condition of either a bad egulator or an out of adjustment regulator? Don't want to damage anything, but was planning a short drive today of 50 miles.
 
Ifin you got your AAA card and cell phone wid you, you might make it back home, I have seen generators come in smoking when the regulator was bad- generator survived and regulator replacement cured the problem. I would take a new regulator to the shop just in case.---Keoke-- ?
 
Gotcha, looks like a highlander day after all. I promise not to add any more to this saga, thanks all.
 
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