Can somone explain WHY positive first when jumping a car battery?...

[Charles Lucas]

On Friday, January 27, 2023 at 9:33:43 PM UTC-6, Xeno wrote:

On 18/1/2023 2:35 pm, mike wrote:

Starters can draw 150 - 500 amps of 12 volt DC current. If the negative
leads aren\'t making a good connection, the car bumpers might make the
perfect substitute. In the days of metal bumpers, having them weld
themselves together is probably not the best outcome. With plastic
bumpers, not so much of an *electrical* issue but you\'ll be scuffing the
paint on them.

Then they said positive first.
Why?

Although the thread is rather lengthy and has been virtually exhausted,
I am going to venture out an explanation here.

Prevents Sparking or Arcing if in the event wires did touch. More energy
passes from the negative (anode) to the positive (cathode) side, due to
the way electrons flow, which create a potential for arcing on the positive
side. So, you go to the \"stronger\" or more energetic side first, then you
apply either the chassis or earth ground. It also puts less strain on the
stator and rotor on the electric motor in your alternator.

Follow or look up this enclosed link below. It gives details on arcing here.

https://getjerry.com/questions/what-are-some-reasons-why-my-car-battery-sparks-when-connecting-the-charger

If you need to constantly add water, I suggest you check your charge
output. Your battery is being overcharged and is gassing the battery.
Doesn\'t do a lot for the longevity of the battery either.

And how do you know how much to add?
They say add water to the \"splash plate\" but what is that?

As long as the electrolyte covers the top of the cell plates, all will
be well.

Accordingly, the batteries (depending upon their chemical composition
and make up) have to maintain the correct specific gravity. Most people
do not know about this, but it ties in when a chemical reaction is actually
created through the EMF of the battery during operation drawing from
each of those cells.

They say the six chambers produce 2.1 volts each for 12.6 volts?
Isn\'t it more than that?

Nope. The electrical system of a car is *14 Volts*, not 12V as is
commonly believed. You need that voltage to charge a 12 Volt battery at
its nominal 12.6 Volts. After charging, the battery will show more than
that but it is only a *surface charge* and will quickly dissipate back
to 12.6. What people don\'t realise is that the battery is *only* for
starting the engine. Whilst ever the engine is running, the car
electrical system is running off the alternator - hence a 14 Volt
system. NB, alternators typically output between 13.8 and 14.2 Volts.

Actually, I heard about 13.5 to 13.8 Volts is common for vehicles
and traditional automobiles with regular gasoline engines. Diesel
uses up to 14.2 volts because
more power is generated through the glow plugs (and with diesel,
the pre-firing). I am not a diesel expert, but that is what I have heard.

Any less and the battery may not fully charge, any more and you will get
gassing.

They say adding water before charging will make it overflow.
Does it really change the water level that much from dead to charged?

Ask yourself what heating water does to its volume and you\'ll have
answered that question.

And what happens if you tap water instead of distilled?

The reaction will be slightly different chemically, but not by much, if the
specific gravity remains intact. I try to get distilled because there is by
nature less sediment in the water which reduces wear on the internal
chambers or cells in the battery and less likelihood of calcification.

Good Luck. Hope this helps.

Charles Lucas

 

[Bob F]

On 1/28/2023 9:19 AM, Charles Lucas wrote:

On Friday, January 27, 2023 at 9:33:43 PM UTC-6, Xeno wrote:
On 18/1/2023 2:35 pm, mike wrote:



Starters can draw 150 - 500 amps of 12 volt DC current. If the negative
leads aren\'t making a good connection, the car bumpers might make the
perfect substitute. In the days of metal bumpers, having them weld
themselves together is probably not the best outcome. With plastic
bumpers, not so much of an *electrical* issue but you\'ll be scuffing the
paint on them.

Then they said positive first.
Why?


Although the thread is rather lengthy and has been virtually exhausted,
I am going to venture out an explanation here.

Prevents Sparking or Arcing if in the event wires did touch. More energy
passes from the negative (anode) to the positive (cathode) side, due to
the way electrons flow, which create a potential for arcing on the positive
side. So, you go to the \"stronger\" or more energetic side first, then you
apply either the chassis or earth ground. It also puts less strain on the
stator and rotor on the electric motor in your alternator.

Follow or look up this enclosed link below. It gives details on arcing here.

https://getjerry.com/questions/what-are-some-reasons-why-my-car-battery-sparks-when-connecting-the-charger

Which says NOTHING to support your silly claim above.

Obviously, every time you connect anything to a car battery, there is a
positive and a negative side to that connection as you do.

Your silly reference claims there is a spark because you left something
on (which on modern cars is always true) but ignores that you are
connecting a charge battery with an uncharged one.

 

[Charles Lucas]

Your silly reference claims there is a spark because you left something
on (which on modern cars is always true) but ignores that you are
connecting a charge battery with an uncharged one.

OK, so I missed that. Here\'s one that does address the dead battery you
would be connecting the vehicle to. My apologies for missing the dead
one that is not charged. Link is below:

https://blog.napacanada.com/en/how-to-safely-and-quickly-recharge-a-dead-car-battery/

There are similar articles to connecting batteries to capacitors (which is basically what a
battery essentially is), although we\'re dealing with DC circuits.

Good Luck.

Charles Lucas

 

[Bob F]

On 1/30/2023 9:34 AM, Charles Lucas wrote:

Your silly reference claims there is a spark because you left something
on (which on modern cars is always true) but ignores that you are
connecting a charge battery with an uncharged one.

OK, so I missed that. Here\'s one that does address the dead battery you
would be connecting the vehicle to. My apologies for missing the dead
one that is not charged. Link is below:

https://blog.napacanada.com/en/how-to-safely-and-quickly-recharge-a-dead-car-battery/

There are similar articles to connecting batteries to capacitors (which is basically what a
battery essentially is), although we\'re dealing with DC circuits.

Good Luck.

Charles Lucas

That article tells you to jump start a car, then

\"If the battery reads below 12 volts, it’s considered “discharged.”
Driving around can’t revive a battery below 12 volts, and attempting to
do so might damage the alternator.\"

If that is true, what has worked for practically everyone that has ever
jumped a significantly discharged battery has risked damaging the
alternator of the car used to jump it. Ever hear of that happening
without reversing the cables?

And driving around has worked fine for millions of people with battery
drained before jumping after they left the lights on.

Parts dealers web pages are highly \"sales biased\", like the one I saw
that claimed that wiper blades should be replaced every 6 months.

 

[Peter W.]

This is the 94th post on the basics of separating fly-shit from pepper - oops, how to jump-start a vehicle. What we have learned:
a) this venue is proof-positive that common sense is rarer than an ethical politician or a moral evangelical preacher.
b) that this venue exists to give the most impractical, obscure, possibly dangerous advice to the mostly lazy, ignorant or otherwise challenged individuals who appear to look for and cherish such device rather than seeking it for themselves, or reaching out to organizations that actually might know.
c) that if there is an opinion - fact-based or not - there will be an equal-and-opposite opinion - fact-based or not.
d) that the posters in this venue as exemplified by the above should not be exposed to anything sharper than a rubber spoon, more powerful than a D-size battery (large enough to make swallowing it difficult), or requiring reading or understanding directions, written or otherwise.

https://magazine.northeast.aaa.com/daily/life/cars-trucks/jumping-a-car-battery/

Now, how hard was that?

Peter Wieck
Melrose Park, PA

 

[Carlos E.R.]

On 2023-01-19 02:01, Rod Speed wrote:

On Thu, 19 Jan 2023 04:54:10 +1100, John Robertson <jrr@flippers.com
wrote:

On 2023/01/17 8:33 p.m., mike wrote:
On 18-01-2023 09:40 Clifford Heath <no.spam@please.net> wrote:

In case there is any hydrogen gas that has developed in the battery
and may be still concentrated enough to burn, any spark from
completing the circuit should be made at some distance from the
battery. That is, but connecting the earth to some metal part of the
chassis, not to the battery terminal itself.
 Thank you for trying to explain why they said here to connect + first.
https://blog.napacanada.com/en/how-to-safely-and-quickly-recharge-a-dead-car-battery/
 Isn\'t there a spark no matter what cable is the last point to be
connected?

The chassis is (usually) negative, which is why that is the first
and last contact point.
 I\'m not disputing that since I\'m the one asking the question, but
didn\'t
that article above say the opposite?
They said to connect a negative cable last to the chassis of the dead
car.

The point is to first connect the positive lead to the battery
positive, and then the negative lead AWAY FROM THE BATTERY by
connecting to the engine metal. In that order for safety.

After the engine starts, then disconnect the negative lead that is
AWAY FROM THE BATTERY so any spark created at the disconnect point is
unlikely to cause the battery to explode if hydrogen gas was created.
Perhaps you left the jumpers connected for a few minutes while
charging the battery which leads to more hydrogen gas

No, because the battery doesn\'t gas unless it is being charged when
fully charged already and that won\'t be happening with either battery.

The \"bad\" battery will start charging when connected, and there will be
no current limiting.

which makes a spark more and more likely/dangerous as time goes on...

--
Cheers, Carlos.

 

[Michael Trew]

On 1/30/2023 16:42, Carlos E.R. wrote:

On 2023-01-19 02:01, Rod Speed wrote:
On Thu, 19 Jan 2023 04:54:10 +1100, John Robertson <jrr@flippers.com
wrote:

After the engine starts, then disconnect the negative lead that is
AWAY FROM THE BATTERY so any spark created at the disconnect point is
unlikely to cause the battery to explode if hydrogen gas was created.

No, because the battery doesn\'t gas unless it is being charged when
fully charged already and that won\'t be happening with either battery.

The \"bad\" battery will start charging when connected, and there will be
no current limiting.

The last time I had a really flat battery, and jumping it didn\'t work
(perhaps the cables weren\'t heavy enough gauge), I started it with
another battery installed (cables semi-tight pushed-on)... then with the
alternator keeping it going, I disconnected that battery, and hooked up
the flat battery. You could instantly hear the engine bog down from the
alternator kicking into high-gear. This was a 1960\'s car, BTW, with a
modern 12v battery. Perhaps this isn\'t the hottest idea with a new car
using expensive electronics, but it works fine on older rigs with a good
alternator.

 

[Charles Lucas]

On Friday, February 3, 2023 at 4:49:25 PM UTC-6, Michael Trew wrote:

On 1/30/2023 16:42, Carlos E.R. wrote:
On 2023-01-19 02:01, Rod Speed wrote:
On Thu, 19 Jan 2023 04:54:10 +1100, John Robertson <j...@flippers.com
wrote:

After the engine starts, then disconnect the negative lead that is
AWAY FROM THE BATTERY so any spark created at the disconnect point is
unlikely to cause the battery to explode if hydrogen gas was created.

No, because the battery doesn\'t gas unless it is being charged when
fully charged already and that won\'t be happening with either battery.

The \"bad\" battery will start charging when connected, and there will be
no current limiting.
The last time I had a really flat battery, and jumping it didn\'t work
(perhaps the cables weren\'t heavy enough gauge), I started it with
another battery installed (cables semi-tight pushed-on)... then with the
alternator keeping it going, I disconnected that battery, and hooked up
the flat battery. You could instantly hear the engine bog down from the
alternator kicking into high-gear. This was a 1960\'s car, BTW, with a
modern 12v battery. Perhaps this isn\'t the hottest idea with a new car
using expensive electronics, but it works fine on older rigs with a good
alternator.

Remember, this can be done only if what this man said is true and/or the
voltage regulation circuitry can handle it. I would try using a load resistor
Run to ground at the base of the circuit to handle the load and to prevent
overload. The resistor should be of adequate size (1/4 watt at so many
mega ohms) to absorb the energy.

Good Luck,

Charles Lucas