jump starting


Old 12-15-06, 02:24 PM
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Join Date: Dec 2004
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jump starting

The other day a friends car wouldn't start. While two of us planned on just jumpstarting the car from ours another friend said doing this with two newer cars(2002&2004) could lead to trashing the cars computers. Pleading total ignorance on this does anyone know wether this is true. If it is are you able to jump start cars at all anymore?
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Old 12-15-06, 02:50 PM
Join Date: Dec 2001
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there are alot of electronics on late model vehicles that could potentially be damaged by jump starting but if you use caution when putting on the cables and make sure they are hooked up correctly and do not short them then you usually will not have a problem.
Old 12-15-06, 02:57 PM
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Read the owners manual on the dead car; it SHOULD give you guidance. SOME vehicles have specific pre-jump requirements such as turning off the radio. Some of the problems are related to the excess voltage being put out by the jumper if the engine is running; this can be somewhat avoided by using a jump-box vice cables or jumping without the engine on the jumper car running so that your output voltage will be limited to about 12-12.5 volts.

Bottom line: Read the owner's manual.

What make/model was the dead vehicle, I can look it up in our towing/service reference manual.
Old 12-15-06, 03:05 PM
Join Date: Jan 2006
Location: Owen Sound Ontario Canada
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I will say that yes boosting can harm a computer as well as other stuff
Just as with your home computer which you use right now, voltage transients can harm the delicate microchips.
We use surge protectors with our home computers or UPS's to flatten out the voltage spikes to the best of our ability.
A UPS is more or less just a lead acid battery and can stabalize the voltage
Just like your car battery.
When boosting both batteries are under load and voltage is down so the batteries cant act as this electrical shock absorber.
My nephew recently took out my fathers computer by boosting his truck and taking the voltmeter down in the red for 10,s of seconds at a time.
A bit of time after the computer quit working proper.
Any spark can be a voltage transient such as a static shock from out hand to the delicate parts of our home computer parts inside. That is why we must take precaution to ground our selves before touching the electronics.
There are safegaurds built into the system but cars are not built as "boosting machines " as a charger/booster would be built.

If I have to boost then I just hook up the cables with both cars off so my alternator is not cranking my voltage up to 14 something volts.
I leave the other car off and just charge the other persons battery with my car. I then disconnect the cables and let then start on thier own.
My car is not too now so if I do fry something I wont be out too much.
But I still dont boost unless I have to.
Old 12-16-06, 05:53 AM
Join Date: Nov 2006
Location: Jersey
Posts: 526
The way I was taught to boost was turn off ALL accessories and keys OFF so there is no load to create a spark when hooking up mostly to avoid an explosion.
Battery gases are very explosive. My co-worker several years ago hooked up a battery and it exploded in his face. Luckily he is OK now after he went to Wills Eye Hospitol for burns to his face and eyes.

Also a good rule to use is put both Red (positive)clamps on first then put the Black ( negitve) on last.

Black, last on, first off. This will minimize sparks.

Then try to start with the engine off. Most times it won't start with engine off. Then start it up and try it. REMEMBER, Black clamps OFF First.

In the old days when they had real metal bumpers you could push the cars bumpers together for the Ground and then just use the Red clamps for the Positive but those days are long gone since everybody has rubber bumpers.
Old 12-16-06, 06:06 AM
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You're dating yourself if you can remember jumping by touching bumpers, Mackey!

Safer way with the cables is to make the LAST connection at a frame or engine ground rather than at the battery. This keeps any sparking AWAY from the battery.

FWIW I HATE doing jump starts because (a) The inherent possibility of electronic problems as addressed, and (b) everyone assumes that if it starts from a jump it will continue to run and maybe even they can milk it for a couple of days until they can replace the battery (if they are CONVINCED it IS the battery). I often have to convince people that they need a tow rather than a jump when they were just "driving down the road and it died and now it won't turn over". The non-beleivers call back five minutes and a couple of miles further down the road when it's died again from their bad alternator.
Old 12-19-06, 04:24 PM
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Join Date: Dec 2004
Posts: 13
Thank You all for the input. Knowlrdge is a great thing

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