[Shop-talk] Jump starting a late model car

[JohnT Blair]

On 12/01/2023 7:21 AM EST you wrote:
 
>I think someone is pulling someone else's leg. There is
>nothing (that I know of) in any post-2000 vehicle that can be
>"fried" by providing or accepting a jump, provide it's done
>properly (+ to + and - to -).
 
Donald,
 
Thanks for the reply.  I agree with you, but I haven't stayed up with the "state of the art" when it comes to the newer cars.  My newest car is a '12 Scion xB.  Everything gets older from there.  I'd never heard of electric parking brakes until my nephew had problems with his.  So I had to come up to speed there.  So that's why I posted the questions.
 
>The "dead" battery does not appear as a short because the
>cables and clamps have significant resistance. That is the
>big reason that the "dead" battery needs to be connected
>for a period of time before cranking. (I usually wait 30 sec
>(longer in winter); not very long, but it really doesn't take
>much to bring a dead battery up to sufficient charge.)
 
Exactly!!!
 
>The protections on vehicle electronics and electrical
>systems are amazing; I've helped design and test quite a
>few of them.
 
Again, exactly what I thought.  How hard is it to put a fuse, a MOV, and or a diode in each circuit to protect it from surges and incorrect polarity.
 
>Protection is built in to every component against: over-
>voltage; reverse connection; shorts to ground; shorts to
>power. The battery itself is a very simple electrochemical
>device that _can_ be damaged, but it's difficult: freezing
>(-40F if charged; -20F if significantly discharged); reverse
>charging; mechanical damage is the most common
>problem.
 
Good info.
 
>Provided the jumper and jumpee batteries are connect
>properly (+ to + and - to -), there is almost no way to
>damage either of the vehicles' systems.
 
My thoughts exactly.  Otherwise you'd have to remove a dead battery to charge it.
 
Thanks for the info.  That reinforces my thoughts exactly.  I just wanted some addition support.
 
JohnT,
 

John T. Blair  WA4OHZ     email:  jblair1948 at cox.net

Va. Beach, Va                    Phone:  (757) 495-8229
 
65 Morgan 4/4 Series V (B1106)     75 Bricklin SV1 (#0887)   48 TR1800    48 #4 Midget  
65 & 77 Spitfire   71 Saab Sonett III   65 Rambler Classic   65 Volvo P1800
 
Morgan:    http://autox.team.net/morgan/
Bricklin:    http://www.bricklin.org/
 

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