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

[Rod Speed]

They weren't hoarding food in survival mode.

No evidence that more would go in with covid around, so no need for more toilet paper than usual.

[Rod Speed]

Mighty✅ Wannabe✅ <.> wrote

Doesnt explain why an enlarged prostate shows up in old age when the male hormone levels have clearly dropped significantly.

I dont either and am almost into my 80s. Never need to piss at night either.

Don't get any effect like that either.

And my PSA tests are fine.

I haven't bothered and have been visibly balding for more than 50 years now.

I am much balder than that and it is genetic, my dad started to thin in his 30 and ended up quite a bit balder than me.

Don't buy that claim with enlarged prostate for the reason I listed.

[David Lesher]

You want the spark when disconnecting to be AWAY from the rapidly charging battery.

So: Run the negative from frame to frame, and disconnect at the rescue car first.

[Rod Speed]

David Lesher [e-mail] wrote

There is no hydrogen when the once flat battery is being charged once the engine has started.

[invalid unparseable]

Rod Speed wrote on 1/19/2023 3:41 PM:

I real life scenario there is no danger of hydrogen accumulation under the hood because it is too airy inside the engine compartment.

There will be danger of hydrogen accumulation if the lead-acid battery is confined inside a box, like underneath a motorized wheelchair.

[Scott Lurndal]

Then why do space launch vehicles use burners to ensure that any H2 that pools around the launch site is burned off before launch?

Far more "airy" environment than any automobile engine compartment.

[invalid unparseable]

Have you actually seen a rocket launch? The launch rocket itself is a gigantic blowtorch which would have blown away or ignited "any H2 that pools around the launch site". Besides, H2 doesn't "poll around the launch site" because hydrogen is much lighter than air. Any leaked H2 would have risen up into the heavens.

[Scott Lurndal]

Yes, and a shuttle landing as a guest at Edwards. Note that the SLS uses shuttle main engines.

"At T minus 10 seconds, the "go for main engine start" command is issued by the GLS. (The GLS retains the capability to command main engine stop until just before the SRBs are ignited.) At this time flares are ignited under the main engines to burn away any residual gaseous hydrogen that may have collected in the vicinity of the main engine nozzles. A half second later, the flight computers order the opening of valves which allow the liquid hydrogen and oxygen to flow into the engine's turbopumps."

[invalid unparseable]

The person who wrote that is definitely not educated enough to know that hydrogen rises and won't stick around at the base of the rocket. That is the most laughable thing a person can say.

The real reason for the flares shooting at the rocket nozzle is an insurance policy that in case the internal ignition mechanism failed to ignite the hydrogen fuel mixture, the flares will guarantee the hydrogen fuel will be ignited.

Image if the hydrogen fuel mixture failed to ignite internally and there is no flare at the nozzle, the rocket will expel all the hydrogen fuel mixture while sitting on the launch pad. Image how big the fireball that will ensue when it does ignite by static charge or random spark one minute later.

[Rod Speed]

In spades when the hood is opened to allow the positive jumper lead to be connected to the battery post.

Not with modern sealed batterys which have a catalyst that recombines the gases back to water and which have the metal used in the plates which ensure that no hydrogen is produced when they are charged.

[Rod Speed]

Because you get FAR more gaseous hydrogen in that situation.

[Rod Speed]

And the important bit is the fact that the fuel is LIQUID HYDROGEN which can see lots of gaseous hydrogen around the area where the fuel will be ignited if there is any leak at all.

[Clare Snyder]

I will respectfully disagree.I have seen numerous batteries explose in open air.

I'll give you 2 examples. When Iwas teaching Auto Mechanics at a secondary school the day I taught about battery safety one of the lads had his '65 Pontiac in the shop and it wouldn't start. He had worn the battery down and decided to change the battery. As usual he had NOT been paying attention in class - and you can guess the rest. One loud "pheew!!!" and there was acid all over the inner fender and floor. Thankfully it blew the bottom out of the battery, not the top. I said "guys, what just happened?" and in one voice they all replied "Blanchard wasn't listening!"

Second example. I was working on the exhaust of my vehicle on the hoist in my brother's shop. He had a motorcycle battery on charge on the workbench about 10 or 12 feet from the hoist and I grabbed the "wheel of death" to cut off a clamp. A spark from the grinder found the battery - and that was the end of the motorcycle battery.

A third example - The old Massy Harris 44 had been a little cranky about starting for several days. One afternoon I went out to restart it after lunch to do some ploughing, and as soon as I hit the starter switch the battery exploded. One of the inter-cell connections inside the battery was fractured and it sparked under load.

All 3 were in open air.

[invalid unparseable]

Clare Snyder wrote on 1/19/2023 10:45 PM:

So it wasn't hydrogen explosion as you have described.

I would say the kid connected the charger the opposite way. That's why the battery fluid immediately boiled over.

Next?

Hydrogen came from the electrolysis of the water in the battery. A motorcycle battery is too small to hold enough water to produce so much hydrogen to cause an explosion. Do you know the inside of a lead-acid battery is tightly packed and it actually doesn't hold a large volume of battery fluid? Anyway, the hydrogen would have risen to the shop ceiling instead of lingering on the shop floor.

Next?

The fracture in the inter-cell connections has much higher electrical resistance than the starter motor so most of electrical energy load was at the location of the fracture. When you engaged the starter the battery heated up so quickly that the resulting steam exploded the battery.

I think my explanations are more reasonable than yours.

[chop]

But the hydrogen wasnt with the third one.

[Clare Snyder]

The kis didn't connect a charger you jack-ass

Agaiin your increfible ignorance is showing

Again you are being ridiculous. And showing your total ignorance of the subject

You are fefinitely a "wannabe"

[invalid unparseable]

Clare Snyder wrote on 1/20/2023 11:00 AM:

You wrote "He had worn the battery down and decided to change the battery".

What did he do? Jump cables?

That would be worse, because a good lead-acid battery can supply a lot higher amperage than an electrical charger in a workshop. When he connected the jump cables in the opposite polarity, then instantly boiled and exploded the dead battery he was trying to jump.

Next?

Are you disputing the proven scientific fact the hydrogen rises because it is much lighter than air?

Next?

Do you know Ohm's Law? Do you know the electrical load is equal to I x R x R (energy = I*R²)? Since the electrical current is the same in a closed circuit, that means the item with the higher resistance in the circuit will take up a higher proportion of the electrical energy load.

I've dispelled all your confusion and misconceptions for you and you are not grateful.

[hubops]

We would collect a small amount from a charging car battery - - by placing a cigar tube over one of the cell-holes - and after just a couple minutes the amount of gas collected would make a dandy pop when ignited. John T.

[invalid unparseable]

[e-mail] wrote on 1/20/2023 12:33 PM:

The electrochemical reaction inside a lead acid battery does not produce H2, the stable form of hydrogen in the atmosphere. The H2 released from a lead-acid battery comes from the electrolysis of water between the two electrodes of the lead acid battery, which is a result of charging at a high rate, or the battery is already full and thus not accepting charge. The excess electrical energy has nowhere to go but to split the H2O into H2 and O2 (electrolysis).

If you have to frequently add water to your car battery, then you must be charging too long too fast, or your car's voltage regulator in the alternator is not functioning correctly so the battery is being overcharged constantly.

[invalid unparseable]

Mighty✅ Wannabe✅ wrote on 1/20/2023 12:10 PM:

Sorry. Now I notice "change the battery", not "charge the battery". My bad. Then he probably dropped, or banged the battery against something and broke it.