Re: Jumper cablesquantumelfMarch 28 2007, 23:07:05 UTC
My dad made me memorize this when I got my driver's license:
"Positive, Positive, Negative, Ground!"
Typically you connect the positive terminal of the good battery to the positive terminal of the bad battery, then the neg terminal on the good battery, then the other negative cable to chassis ground on the car with the bad battery.
The reasons are as follows...
Current flows from positive to negative (or positive to ground.) If you connect both terminals of the good battery first, you risk (scenario 1) the other two cable clamps touching each other while you are walking over to the other car, thereby shorting out the good battery or creating massive sparks. If you connect positive on good car, with positive on bad car and then negative on bad car before neg on good car, you risk (scenario 2) draining the good battery of the first car enough that it won't have enough juice to support the turnover of the second car. This is because you complete a circuit within the bad battery which is receiving its ion source from the positive terminal of the good battery. If you leave the first car running, this can somewhat protect against scenario 2, but you still risk giant sparks near batteries as in scenario 1. Sparks near batteries are bad. This is also the reason for connecting to chassis ground on car 2 rather than its negative terminal, to avoid creating a spark at the negative terminal of the battery.
"Positive, Positive, Negative, Ground!"
Typically you connect the positive terminal of the good battery to the positive terminal of the bad battery, then the neg terminal on the good battery, then the other negative cable to chassis ground on the car with the bad battery.
The reasons are as follows...
Current flows from positive to negative (or positive to ground.) If you connect both terminals of the good battery first, you risk (scenario 1) the other two cable clamps touching each other while you are walking over to the other car, thereby shorting out the good battery or creating massive sparks. If you connect positive on good car, with positive on bad car and then negative on bad car before neg on good car, you risk (scenario 2) draining the good battery of the first car enough that it won't have enough juice to support the turnover of the second car. This is because you complete a circuit within the bad battery which is receiving its ion source from the positive terminal of the good battery. If you leave the first car running, this can somewhat protect against scenario 2, but you still risk giant sparks near batteries as in scenario 1. Sparks near batteries are bad. This is also the reason for connecting to chassis ground on car 2 rather than its negative terminal, to avoid creating a spark at the negative terminal of the battery.
*bows politely and exits stage left.*
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