Is it bad to jump-start cars with "computers" in them?

MeddyDuo

Senior member
Jan 15, 2007
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I was told by somebody that if you have a car with a "computer in it" (I'm guessing she meant some sort of electronic chip) then it is bad to jump-start it or to jump-start another car with it.
This doesn't really make sense to me, because don't almost all cars, even if they are old, have some sort of chip in them? Or only cars with EFI?
 

Furyline

Golden Member
Nov 1, 2001
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It is not bad. The computer was certainly designed and tested to withstand jump start conditions.
 

thomsbrain

Lifer
Dec 4, 2001
18,148
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as long as you connect the wires with the target car turned fully off and the source car turned on, i don't see how the computer could experience conditions that differ from normal in any way. i've personally jumped plenty of cars with computers and never had a problem.
 

Ika

Lifer
Mar 22, 2006
14,264
3
81
I'm sure they would take jump-starting into mind when car companies design the cars.
 

LordMorpheus

Diamond Member
Aug 14, 2002
6,871
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well damn, better not jumpstart anything built after 1980, then . . . .

Here's a hint, go find your owner's manual for your car. It'll have a section on how to jumpstart it or use it to jumpstart another vehicle. Unless it's a classic, it's got a computer in it. The manufacturers don't tell you it's bad, and how often have you heard of the computer failing in a car?
 

brxndxn

Diamond Member
Apr 3, 2001
8,475
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That's just plain stupidity based on stupid stupid.

It is bad to jump-start a car with a powersource that cannot provide the necessary cranking amps.. For example, you would not want to try and jump-start a 6.0L V8 with a tiny 1.8L 4cyl. However, 'overpowering' a car by jumping it does not hurt it (correct me if I'm wrong) because the car will only use the amount of power that it needs. That's why you only need to meet or exceed the amount of rated cranking amps on the car battery when you choose one. It is only harmful to the components if there is not quite enough power being given to the engine to start it.

It sounds to me like whoever said that had some correctness in what they were saying.. and then it was 'telephoned' from person to person with each next person mangling the original statement until it turned into the crap the OP presented.

 

biggestmuff

Diamond Member
Mar 20, 2001
8,201
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Why would you think that?

Originally posted by: MeddyDuo
I was told by somebody that if you have a car with a "computer in it" (I'm guessing she meant some sort of electronic chip) then it is bad to jump-start it or to jump-start another car with it.
This doesn't really make sense to me, because don't almost all cars, even if they are old, have some sort of chip in them? Or only cars with EFI?

OH!! Now I understand.
 

BUTCH1

Lifer
Jul 15, 2000
20,433
1,769
126
I wont jump start anyone. A lot of the time someone's left their lights on ALL day wich
means the Batt. will be completely dead and will strain the crap out your alt. or smoke
the jumper cables.
 

Tuktuk

Senior member
Jan 30, 2007
406
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Originally posted by: BUTCH1
I wont jump start anyone. A lot of the time someone's left their lights on ALL day wich
means the Batt. will be completely dead and will strain the crap out your alt. or smoke
the jumper cables.

This lady that gave me a jump once was so nice, she asked me if I knew how to do it right because the last time she helped a stranger with a jump, she had to spend over a thousand dollars to repair something. Whether it was actually the fault of the jump or not I don't know, but for her to help me out after someone else ruined her car was really nice. She just asked me if I knew what I was doing first :p
 

gsethi

Diamond Member
Feb 28, 2002
3,457
5
81
Originally posted by: Tuktuk
Originally posted by: BUTCH1
I wont jump start anyone. A lot of the time someone's left their lights on ALL day wich
means the Batt. will be completely dead and will strain the crap out your alt. or smoke
the jumper cables.

This lady that gave me a jump once was so nice, she asked me if I knew how to do it right because the last time she helped a stranger with a jump, she had to spend over a thousand dollars to repair something. Whether it was actually the fault of the jump or not I don't know, but for her to help me out after someone else ruined her car was really nice. She just asked me if I knew what I was doing first :p

did she end up spending another 1000 after helping you ? :p
 

BUTCH1

Lifer
Jul 15, 2000
20,433
1,769
126
The #1 cause of returned alts. is installing in a car w/ a totally dead battery then jumping
it to get it started, now the alt. is seeing almost a dead short trying to recharge it. Correct
way is to charge batt. w/a re-charger before first start. Since my batt. is inside a box I
usually just offer a ride to them.
 

DrPizza

Administrator Elite Member Goat Whisperer
Mar 5, 2001
49,601
167
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www.slatebrookfarm.com
Originally posted by: BUTCH1
The #1 cause of returned alts. is installing in a car w/ a totally dead battery then jumping
it to get it started, now the alt. is seeing almost a dead short trying to recharge it. Correct
way is to charge batt. w/a re-charger before first start. Since my batt. is inside a box I
usually just offer a ride to them.


I have a battery charger and use that if I needed a charge. However, how the heck do you smoke the jumper cables?! You must have some really cheap crappy jumper cables that aren't designed well for jumping most vehicles.
 

RossGr

Diamond Member
Jan 11, 2000
3,383
1
0
To the best of my knowledge the alternator is not designed to carry starter current. If the source car is running when you jump a dead battery you will be putting your alternator at risk. The solution is to either run the source car until the dead battery is charged and can start the car itself. Or.

Start the dead car without starting the source car. Thus the source battery provides the current, not the alternator.
 

nakedfrog

No Lifer
Apr 3, 2001
61,143
16,614
136
Originally posted by: DrPizza
Originally posted by: BUTCH1
The #1 cause of returned alts. is installing in a car w/ a totally dead battery then jumping
it to get it started, now the alt. is seeing almost a dead short trying to recharge it. Correct
way is to charge batt. w/a re-charger before first start. Since my batt. is inside a box I
usually just offer a ride to them.


I have a battery charger and use that if I needed a charge. However, how the heck do you smoke the jumper cables?! You must have some really cheap crappy jumper cables that aren't designed well for jumping most vehicles.

I'm picturing 24 gauge wire hooked up to alligator clips or something...
 

Pepsi90919

Lifer
Oct 9, 1999
25,162
1
81
Originally posted by: thomsbrain
as long as you connect the wires with the target car turned fully off and the source car turned on, i don't see how the computer could experience conditions that differ from normal in any way. i've personally jumped plenty of cars with computers and never had a problem.

cars are never "fully turned off"
 

eplebnista

Lifer
Dec 3, 2001
24,123
36
91
Originally posted by: LordMorpheus
how often have you heard of the computer failing in a car?

I had a computer module(aka brain) die on me in a mitsubishi mirage when it was about 6 years old. A large black barrel diode had fried in it, you could see its charred remains through the clear silicone? it was encased in after the cover had been removed. IIRC, it was about $400 to replace it with a used one. The car was NOT used to jump anything off though, I guess you could say it was natural causes.
 

compnovice

Diamond Member
Jun 18, 2005
3,192
0
0
This is how I jumpstart a car or have my car jumpsarted:

1) Connect Cables
Source Car: Red +ive
Black -ive
Target Car: Red +ive
Black: Ground

2) Start source car; let it run for a few minutes
3) Start Target car
4) Disconnect cables

Am I doing something wrong?
 

db

Lifer
Dec 6, 1999
10,575
292
126
You have to connect correct polarity, otherwise you can burn out the diodes=you need new alternator.
Don't believe it when someone says "I know how to do this"; watch to make sure, or you lose.
And yeah, above comment correct: if battery is totally dead, jumping won't start it. Must be charged with a charger first--at least 1/2 way up.

Almost all cars have "computers". Not an issue.
 

Lithium381

Lifer
May 12, 2001
12,452
2
0
as long as you put the polarity correctly, and hook them up in the correct order, should be fine