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Negative Earth Mixup please help

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0123 Mike D
Biddulp, Staffs, UK   GBR
Does yer no that for a fact Phill?

I assumed Andrew had got it to start.

So I felt free to encourage Jim
to learn folks some techy stuff smiling smiley

In reply to # 25364 by 66jalopy And his car still doesn't start.

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emjay Jim English
Marietta, PA, USA   USA
For your entertainment while we wait for an update on the Andrews sparks. I don't see "System International unit for force / SI unit is Kilograms per Metre Square Metre."

Pressure is Pascal = Newton / square meter or kilogram per meter per square second or similar denominations.

Force is Newton = kilogram meter per square second as in Force = mass times acceleration.

Yield stress of tin is 9-14 Mpa. Contact normal force for tin 100-500grams or 0.98-4.9Newtons.

area = F/P = 0.98N/14000000Pa =0.00000007sqM or 0.070 sq mm. Using the other limits 4.9/9000000=0.0000005 or 0.544 sq mm. That would be the total effective contact area for each of the rolled sides of the contact. That is why connectors heat up more than wires but the distance is so short and the surrounding structure acts as a heat sink everything is manageable when within operating limits. Temperature rise is a critical parameter for contact/connector design. As I recall the max temperature target is something like 125°C meaning as the ambient temp rises the allowable current must be lower.

The good ole Tin Commandments. See #2
http://www.te.com/documentation/whitepapers/pdf/sncomrep.pdf

0123 Mike D
Biddulp, Staffs, UK   GBR
You have my unfettered permission to please yourself Jim thumbs up

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0123 Mike D
Biddulp, Staffs, UK   GBR
Have you solved your problems please Andrew?

In reply to # 25297 by andrewdh Hi.

Number one Son tried to Jumpstart our 1958 Minor but connected the Jumpstarter to to the battery the wrong way around. In his defence I suppose he attached the black to the black unfortunately because its been converted from positive earth to negative earth the Black as they say was in fact the red.

So he connected positive to negative and negative to positive and then tried to start the car, nothing much happened except he noticed a brown smell coming from the Alternator (it has one of those as well).

I disconnected the Jumpstart battery and in a vain hope than nothing bad had happened reconnected it the right way around. The ignition light came on and the petrol pump ran but pulling the start button doesn't do anything, silence ensued.

So before he becomes Number Omega Son what is he likely to have blown, Solenoid, Starter Motor, Coil, I think the Alternator is shot he said a decent amount of smoke came out of it and when I arrived in the Garage it smelt terrible.

Thanks in advance.

Andrew

andrewdh Andrew Harrison
Rougham, Suffolk, UK   GBR
Hi, I sourced a replacement plug and fitted it with a new Alternator, the car is running fine. Number one sons mixup wasn't too expensive.

Thanks for the advice

andrewdh Andrew Harrison
Rougham, Suffolk, UK   GBR
Thanks for all your advice, i changed the connector, fitted a new alternator and Grasshopper, the car is Green is back on the road.

Andrew

0123 Mike D
Biddulp, Staffs, UK   GBR
smileys with beer

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andrewdh Andrew Harrison
Rougham, Suffolk, UK   GBR
Yes thanks for the help. New Alternator, new connector, its all working fine.

Regards
Andrew

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