# Is it dangerous to jump-start a modern car?

**URL:** <https://boards.straightdope.com/t/is-it-dangerous-to-jump-start-a-modern-car/436747>\
**Category:** Factual Questions\
**Created:** [February 8, 2008, 1:14am UTC](https://boards.straightdope.com/t/is-it-dangerous-to-jump-start-a-modern-car/436747 "2008-02-08T01:14:08Z")\
**Posts on this page:** 2\
**Page:** 2

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**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\
**Post date:** [February 8, 2008, 3:31pm UTC](https://boards.straightdope.com/t/is-it-dangerous-to-jump-start-a-modern-car/436747/21 "2008-02-08T15:31:58Z")

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While they may be able to survive an 80 volt surge, you may not be able to start a car with a 24V jump. On many cars the computers will shut down and refuse to work if the voltage is either too high or too low. I know some of the modules on the cars I work on will go into standby mode and refuse to work at about 16.5-17 volts.  
Also some cars have over voltage protection via a zeiner diode wired to ground via a fuse. If the voltage rises above the reverse voltage threshold the zeiner conducts it to ground and the fuse blows protecting the control unit against over voltage. On the one car I am thinking of the zeiner was set at 22 volts. Every time a customer got a jump, they came in with a ABS warning light due to the blown fuse.  
I haven’t seen that in years, so I think that tow truck designers may have wised up, and no longer provide 24 volt jumps.

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**Author:** ![gotpasswords](https://avatars.discourse-cdn.com/v4/letter/g/c57346/32.png) [@gotpasswords](https://boards.straightdope.com/u/gotpasswords)\
**Post date:** [February 8, 2008, 4:25pm UTC](https://boards.straightdope.com/t/is-it-dangerous-to-jump-start-a-modern-car/436747/22 "2008-02-08T16:25:25Z")

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[QUOTE=Rick]  
Yes I did.  
One little tidbit Mr. Gross is over looking…  
Seriously, who is this guy? I have never heard of him.  
[/QUOTE]

So tell me what you really think about him. 😛

[Who is Pat Goss?](http://www.goss-garage.com/modules.php?op=modload&name=PagEd&file=index&topic_id=0&page_id=27) Most notably, a longtime correspondent on TV’s _Motorweek_

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