Why do British Leyland vehicles have notorious electrical issues?

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Discussion Overview

The discussion revolves around the electrical issues commonly associated with British Leyland vehicles, particularly focusing on the performance of generators and the implications for car electrical systems. Participants explore concepts related to electromagnetic principles, battery usage, and the specific challenges faced in older vehicle models.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants suggest that Lenz's law explains the difficulty in turning a generator when a load is connected, as it induces a current that opposes changes in magnetic flux.
  • Others describe the concept of "electromagnetic drag," noting that increased electrical load results in greater resistance to rotation of the generator.
  • One participant shares a personal experience of running a car on battery power after the alternator failed, indicating that the age and electrical demands of the vehicle affect battery life.
  • There is a discussion about using a relay or toggle switch to cut out the alternator to reduce electromagnetic drag for racing purposes.
  • Concerns about the electrical systems of British Leyland vehicles are raised, with one participant mentioning plans to completely re-wire a TR7 due to the notorious reputation of its electrical issues.
  • Participants express curiosity about the duration a car can run on battery power without the alternator, with varying opinions on the factors that influence this duration.

Areas of Agreement / Disagreement

Participants express a range of views on the electrical issues faced by British Leyland vehicles, with no consensus on the best approach to address these problems. There is also uncertainty regarding the specifics of battery life and electrical load impacts.

Contextual Notes

Limitations include the lack of detailed mathematical analysis regarding battery life and electrical load, as well as varying definitions of terms like "electromagnetic drag." The discussion does not resolve the complexities of the electrical systems in older vehicles.

Who May Find This Useful

Individuals interested in vintage car restoration, particularly those working on British Leyland models, as well as those curious about the principles of electromagnetism in practical applications.

linux kid
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Have you ever cranked a generator? When it's not connected to anything it's easy to turn but when you connect it to a something (like a light bulb) it gets hard to turn.:confused: Why is that?
 
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I think Lenz's law could explain this one :smile:. unfortunately, I do not have enough time to post a complete answer, but basically Lenz's law states that the current is induced in a direction such to oppose any chnages in magnetic flux, thus producing a force. Try googling for Lenz's law.

~H
 
The work done by your load must be done on the generator. When there is no load you do no work, therefore it is easy to turn. When a load is attached you must provide the energy which does work at the load therefore it is harder to turn.

Think of it of "pushing" electrons through the load.
 
Can't give you any math on it. We just used to call it 'electromagnetic drag'. The more electrical load there is, the more resistance there is to rotation. In fact, we used to have 'alternator cut-out' switches in our cars so we could drop the EM drag out of the picture for racing. It's worth a few horsepower.
 
Interesting. How long can a car run on battery (without the alternator)?
 
I really don't know, gnome. I made it home from over 20 miles away, with my low-beam lights on, when my alternator packed it up a few years ago. Of course, with the age of my vehicles the only electrical draw when running (except for the lights) is the ignition system. Those new things full of computers and electric fans and such are probably a different story.
 
Oh, I wasn't even thinking about computers & such; just wondering about how long the battery can supply ignition. I'm thinking in terms of a project I'm planning for this summer -- a 1980 TR7.

So, your alternator cut out would be what -- a relay breaking the circuit between the alternator & battery?
 
You could use a relay. We just spliced a regular toggle switch into the wire. I think that the only way you can figure out the life of a battery that's not being charged is to disconnect your alternator and let it idle. I rather suspect that it might run out of gas before it runs out of electricity. If it's a major concern, you could always replace your stock distributor with a magneto. That supplies it's own power from the engine rotation.
 
No - not a major concern. Just curiosity. Thanks.
 
  • #10
Gnome, electrics should be the least of your worries with a TR7 project! :smile: Start worrying about rust!

My fan belt snapped on my 1600 Seven; I got about 120 miles before I needed a boost. The battery was about 1 year old at the time, and was running no electrical ancilliaries except for the ignition, instrumentation and indicators. (Fan is electric but switchable.)

Gnome, you in the UK?
 
  • #11
To teach us to appreciate the power of a field generator, our junior high school electronics teacher, Mr. Murphy, invited us to hold the leads while he cranked. Yeow!

Might this thread be referring to reverse EMF? Both mechanical friction and inductive impedances play a part in the initial description.
 
  • #12
brewnog said:
Gnome, electrics should be the least of your worries with a TR7 project! :smile: Start worrying about rust!

Gnome, you in the UK?
No -- opposite side of the ocean. My TR7 spent most of its life in the southwest, so actually rust isn't an issue. Electrics, on the other hand, what a mess ... It lives up (or down) to all the wonderful things people say about British Leyland electrical systems. We're definitely going to totally re-wire it.
 

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