1971 MG Midget with a Strange Alternator Fault
Discussion
In early 1983, all of the adults in my family had lost their job owing to the Recession. Borrowing £30 from my grandma, I rented a £20/month old garage, placed an advert in the local press and started my own car repair business.
Doing mostly clutches and servicing, it was a success. With my dad helping, we worked our socks off. I was 18 and still wonder why folk would hand their car keys to me when I looked about 12. I was still getting asked for ID when I was 30.
I remember one car, a student's MG Midget with the 1275 Austin engine and Lucas alternator. Returning home for Christmas, he charged the battery on the old car. Each time he connected the second lead, there was sparking so bad, he asked us to take a look. If the alternator was disconnected, all was well. The car ran and everything but the fuel gauge worked.
As the Lucas ACR alternator is so simple in the wiring department, we tried a new alternator. Same fault. Then another. To cut a long story...
Two auto-electrician men couldn't work it out.
Can you?
All clues are above. The car's wiring is just fine. The alternator was also in good order.
I will answer straight away in another post, otherwise I'll forget and you'll hate me :-)
Doing mostly clutches and servicing, it was a success. With my dad helping, we worked our socks off. I was 18 and still wonder why folk would hand their car keys to me when I looked about 12. I was still getting asked for ID when I was 30.
I remember one car, a student's MG Midget with the 1275 Austin engine and Lucas alternator. Returning home for Christmas, he charged the battery on the old car. Each time he connected the second lead, there was sparking so bad, he asked us to take a look. If the alternator was disconnected, all was well. The car ran and everything but the fuel gauge worked.
As the Lucas ACR alternator is so simple in the wiring department, we tried a new alternator. Same fault. Then another. To cut a long story...
Two auto-electrician men couldn't work it out.
Can you?
All clues are above. The car's wiring is just fine. The alternator was also in good order.
I will answer straight away in another post, otherwise I'll forget and you'll hate me :-)
The clue lies in the chump* returning from Uni and finding the car's flat battery, he decided to charge it: He Reverse-Charged the Battery:-
The battery was so utterly flat (old lead-acid batt tech and old batt charger too here, so batteries don't terminally fail if the charge voltage or EMF ((if you are a physicist, lol)) drops too much) that when he connected the charger leads the Wrong Way Round, the robust old-style charger eventually reversed the polarity of the battery.
When he refit the battery and cables, the alternator diodes protested, causing the sparks and ruining two good alternators. A 'new' battery was all that was required.
Around one year later, he wanted all of his money back.
He'd snapped off the +Ve terminal when he tried to charge it!
It was free!
He then proceeded to argue the toss with my dad.
Showing off his 'superior' intellect - as he arrogantly called it and very foul language too - to my dad, dad ran rings round him. You see my late father was one of the most intelligent men I've ever met. A brilliant dad and a thoroughly decent man too.
From memory, the bill came to £29. The new alternator was £19.00 and we spent all day, plus stood the auto-electricians' bills ourselves. Idiots for being so nice. I just remembered that he never even fully paid the £29 anyway!
Did You Get the Right Diagnosis?
Top marks if you did! It took us about sixteen hours between us in 1983 :-)
The battery was so utterly flat (old lead-acid batt tech and old batt charger too here, so batteries don't terminally fail if the charge voltage or EMF ((if you are a physicist, lol)) drops too much) that when he connected the charger leads the Wrong Way Round, the robust old-style charger eventually reversed the polarity of the battery.
When he refit the battery and cables, the alternator diodes protested, causing the sparks and ruining two good alternators. A 'new' battery was all that was required.
- I call him a chump because: he was studying advanced physics. He should have been able to charge a simple lead/acid 12v battery!
Around one year later, he wanted all of his money back.
He'd snapped off the +Ve terminal when he tried to charge it!
It was free!
He then proceeded to argue the toss with my dad.
Showing off his 'superior' intellect - as he arrogantly called it and very foul language too - to my dad, dad ran rings round him. You see my late father was one of the most intelligent men I've ever met. A brilliant dad and a thoroughly decent man too.
From memory, the bill came to £29. The new alternator was £19.00 and we spent all day, plus stood the auto-electricians' bills ourselves. Idiots for being so nice. I just remembered that he never even fully paid the £29 anyway!
Did You Get the Right Diagnosis?
Top marks if you did! It took us about sixteen hours between us in 1983 :-)
Gassing Station | Home Mechanics | Top of Page | What's New | My Stuff