Swapping batteries w/ vehicle running. Is this ok?

[Tripleshot]

You pull a stunt like that and you will get a darwin award. My son will give you his darwin award. He tried doing that on his car, and just spent over a thousand to replace the computer that runs the whole friggen engine. Who ever came up with this idea that you can do this is a flaming retard.:disgust:

 

[Tominator]

Show me ANY shop manual, owners manual or automotive reference manual that suggests doing a hot swap. Just one. I'll shut up.....maybe...

 

[Zenmervolt]

<<Many newer cars recemmend you NEVER even jump them with cables!>>

Why is this exactly? I can fully understand why you shouln't hot-swap a battery, but the whole no jump-starting period thing leaves me scratching my head. Is it perhaps protection against people who don't bother to turn off all their accessories when jump-starting so that those people can't fry their electrical system and then blame the manufacturer? I mean, all you are doing is hooking up another 12V source in series with the original battery, it doesn't make sense that this would create problems unless you hooked things up in reverse or something equally inattentinve.

ZV

 

[StageLeft]

I HAVE NEVER entered an AT thread with so much misinformation in my life. Half the people here say the world will end and half will say it's no problem and both sides seem equally convinced of this. Then we have one guy saying to plug in negative then positive when hooking up a battery and another guy saying the opposite.

God I'm confused reading this!!!! I'm leaning towards not hot swapping on a new car now based upon filtering out the info below, but I still don't know about hooking up a battery. I always thought that you hook up pos first then negative, and when unhooking pull the ground (negative) first. What's up?

 

[Uconn411]

I didn't mean to start an argument over all this.... I think that if you value you're vehicle and aren't confident with swapping batteries, don't do it. If you have a modern vehicle with fuel injection and computers running the show, don't do it. But for older vehicles, that have no sensitive electronics onboard, there isn't much to lose. Except if a spark somehow flies into the carb.

 

[Hamburgerpimp]

Redneck

 

[Pacfanweb]

<<That is completely false. Even a dead battery completes the circuit and why would you jump a car with no battery? That makes no sense. >>

Dead wrong. Not all dead batteries complete the circuit. Some are completely open. I have seen many.

<<If you told that story to any Ford Tech, he'd cringe at the though of doing what you suggest>>

Wrong again. We have about 70 working here, and they'd all agree with me.

<<Mis-information! It doesn't matter where it comes from.>>

Yeah, I guess it doesn't matter that I've seen and/or done what we're talking about here done thousands of times without the problems you say will result. I guess that's misinformation. I'm sorry, I thought misinformation was telling someone something that was wrong, which, I did not.
Yes, the official position is not to disconnect the battery while running. That's the official company position. The reality is, 99.9% of the time, it won't hurt anything. The proof is in the pudding. I've seen and done this many more times than you have, I'd wager. I'd say experience is reality.
I don't try to tell you how to drive 18 wheelers, (If I remember correctly, that's what you do, or at least did awhile back), so don't start telling me the in's and out's of working on cars for a living. Do you even know what a diode does anyway? Sheesh.

From Ford's website:
<<When you're ready to jump-start

· Make sure battery terminals are clean: remove excess corrosion if necessary (see Batteries under Maintenance tips).
· Position cars close enough to extend cables between them. Set parking brakes in both.
· Switch off all accessories, except for the heater fan. Turn it on (in both cars) to help protect against an electrical surge.
· Connect the positive (+) terminal (use red cable) of the disabled battery to the positive (+) terminal of the boosting battery. Be careful to keep the clips on the jumper cables from touching together.
· Connect the remaining booster-cable clip to the negative (-) terminal. Be sure to use the black cable of the booster battery. Connect the other clip to any piece of bare metal under the hood of the disabled vehicle, such as the alternator mounting bracket, to complete the circuit. Connect the other end to the alternator mounting bracing stud of the disabled vehicle.
· DO NOT CONNECT DIRECTLY TO THE NEGATIVE (-) TERMINAL OF THE DISABLED VEHICLE. This could cause sparks that could lead to an explosion.
· Start the boosting vehicle and rev engine slightly.
· Start engine of second vehicle.
· Run both vehicles for three minutes before disconnecting leads.
· Remove cables in reverse order. (Both negative ((-)) sides first.)
· Allow jumped car to run for a while to "relearn" its idle position. >>

So they don't recommend you jump start cars nowadays, huh?

 

[Pacfanweb]

Official line: Don't hot swap.

Advice to original question: you can do it to get where you need to go, but don't make a habit of it.

I have seen many, many cars come in without a battery at all. We hook a jumper up, start it, remove the jumper and drive it in. Never hurts anything.
That's not to say it can't, but I've seen it done many times before and it hasn't hurt anything.

By and large, you'll be better off not doing it, but in a pinch, it will not hurt anything.

Think about it. The car is running off the alternator, not the battery. If you disconnect the battery while the engine is running, you haven't introduced a load to the alternator. You've actually reduced the load, especially if you just started the car. I've seen cables removed from running cars many, many, many times, more than anyone else that has posted in this thread, and regardless of what they SAY can happen, we've never seen it.
Again, to be safe, don't do it. The kid in question seemed to be in a bind, and given his situation, he could easily do it and not have a problem.

Edit: Skoorb: yes, the negative is always the first to be disconnected, and last to be connected.

 

[Zenmervolt]

<<So they don't recommend you jump start cars nowadays, huh?>>

While Ford may still reccommend jumping a vehicle, I have seen some cars where the manual advised against it unless there was absolutely no other option.

ZV

 

[Pacfanweb]

<<Show me ANY shop manual, owners manual or automotive reference manual that suggests doing a hot swap. Just one. I'll shut up.....maybe... >>

Never said it was in there. I originally said, was :
<<Hot-swapping a battery isn't recommended as a daily practice, but to get you where you're going once or twice, it's ok. >>

I stand by that statement. Won't hurt a thing.

BTW, Tom, you said this:
<<Many newer cars recemmend you NEVER even jump them with cables!
When you disconnect the battery with the engine running the chargeing circuit immediately is taxed beyond it's design! It maxes out instantly with a huge strain on the circuits. Damage is almost unavoidable. >>

What's up with that? That statement is absolutely wrong, laughable really. If you disconnect the battery, the alternator does NOT "max out instantly". Why would it? The voltage regulator raises and lowers output according to load. If you disconnect the battery, you have not raised the load. The alternator in this situation would be nowhere near full output.

 

[mastertech01]

Skoorb, you are correct, disconnect negative first, connect positive first.
I have never done a hotswap, and see no reason too unless in dire emergency, like stuck in the middle of the desert. Spend a few dollars at the local 7 eleven and get a cheap pair of jumper cables.

Jump starting cars of course must be done with care. It is usually recommended that you use the engine as ground rather than the battery negative post to prevent a spark that may explode the battery in those rare instances where excessive gas has accumulated and I would recommend that for most amateurs especially. I have jump started thousands of new cars and never hurt the electrical system, but then thats where I make my living.

Do clean your battery cables and make sure they are tight before doing anything, as many times a no crank is simply dirty and or loose cables. If you know you ran down the battery from leaving an accessory on, then simply jump start it and run it at least 15 minutes, preferrably at 1500-2000 rpm before driving off. Try restarting in place before you drive off to ensure you can restart if you should kill the engine 2 miles away from your jumper. Many batteries will not recover if they are drained completely.

There are a lot of opinions here but I have never killed an electrical component by removing the negative cable while the vehicle is running. That has been an old trick to test a charging system for many years and I have not seen any Ill effects from it even on the most advanced electronic vehicles to date. It is however not necessary, and I dont do it as a practice, as a simple voltmeter check will tell you if you are getting over battery base voltage charged into the battery. However you really cant get an acurate test of a charging system untill you have a fully charged battery.

Im sure some cars are more sensitive to voltage surges than others, and I have seen a lot of GM cars with this problem, but to date I have not had a Ford that would suffer a problem from jump starting properly or as mentioned from a negative battery cable removal.. hell think about it... loose battery cables would kill your system if they were that sensitive.

Just my experiences...

EDIT... LOL well it seems many more replies since I slowly typed this... Well I think many good points have been made..

 

[CraigRT]

<< Mis-information! It doesn't matter where it comes from. >>





<< If you told that story to any Ford Tech, he'd cringe at the though of doing what you suggest. Where do you work? I want to add that dealership to the places to never take my car. >>



I agree to this response of the original post.. that is BS. I would have responded just like Tominator ( quoted above ) if I read that...

Hot swapping is ridiculous and I would NEVER try it... I don't even like jumping a car and taking off the connections right away.. When you jump a car, you are suppose to let the 2 cars regulate for a while instead of getting it running and disconnecting them right away.. Some people really have no idea how to do it, Just about what-ever you try seems to have some sucess for people, but it doesn't make it safe, or right...

 

[Pacfanweb]

<<Im sure some cars are more sensitive to voltage surges than others, and I have seen a lot of GM cars with this problem, but to date I have not had a Ford that would suffer a problem from jump starting properly or as mentioned from a negative battery cable removal.. hell think about it... loose battery cables would kill your system if they were that sensitive.

Just my experiences...>>

And mine.

edit:
<<There are a lot of opinions here but I have never killed an electrical component by removing the negative cable while the vehicle is running. That has been an old trick to test a charging system for many years and I have not seen any Ill effects from it even on the most advanced electronic vehicles to date.>>

Exactly what I said from the get-go. I've done this more times than I can count on computer controlled vehicles, with no problem.

..........Now that time this guy brought their car into the shop after he hooked the battery cables up backwards.....that was a mess.

 

[Barnaby W. Füi]

i dont know thaaat much about cars, but some of you have no idea what you are talking about as far as circuits and electronics go.

if you dont know what you are talking about, then please stop making yourself look stupid.

 

[XMan]

Pacfanweb, my dad said almost exactly the same thing you did - and he owns his own auto shop.

I'm sold.

 

[dude]

Make sure you let the new fresh water sit for a few hours if possible first. Then change half the water in the tank with new water. Add some solution to the water to keep it's pH balance. That will keep your goldfish alive and well. They'll thank you for it by not floating upside down for a few hours.

 

[Zenmervolt]

<< i dont know thaaat much about cars, but some of you have no idea what you are talking about as far as circuits and electronics go.

if you dont know what you are talking about, then please stop making yourself look stupid. >>



If this was in reference to my post where I said that jumping is just hooking up another battery in parallel, I'll admit to not knowing a whole hell of a lot about the theoretical aspects of a car's electrical system. I could probably infer a little bit from a schematic, but not a lot. However, that lack of knowledge on my part is the reason that I mentioned that as part of a question. I was actually hoping to be shown to be wrong and to get an explanation as to why a jump start is not as simple as hooking up another battery in parallel.

ZV

 

[Pacfanweb]

ZV, you are correct. In fact, you are using the jumper cables to connect the batteries in parallel.

If one battery is dead enough, many times you won't be able to jump start with another car. I can't tell you how many people have come in and said "it's not the battery, we already tried to jump it and it did nothing". Then I go right out with a portable jumper and fire it right up.

 

[Tominator]

<< What's up with that? That statement is absolutely wrong, laughable really. If you disconnect the battery, the alternator does NOT "max out instantly". Why would it? The voltage regulator raises and lowers output according to load. If you disconnect the battery, you have not raised the load. The alternator in this situation would be nowhere near full output. >>



If you could quit laughing long enough you might want to go to some kind of school for the proper way to be a mechanic, because you aren't one!



<< Pacfanweb, my dad said almost exactly the same thing you did - and he owns his own auto shop. >>



WHERE! Another for my list of shops to avoid.

Btw, I gather my knowledge from the experience of 10years selling auto parts. During that time, I was schooled by various vendors includeing a 30year business that rebuilt electrical components and Mendenhall Rebuilders. The taking off of the battery cable to check output is a throwback to the days where generators were checked using this method. The practice was carried over to alternator equipped cars and has been ruining chargeing systems ever since.

 

[CYLINDERMAN]

Tominator is exactly correct!

Even if you dont cause the failure of a component it will shorten the life of one.

Best solution get jumper cables while you have ride or maybe small batery charger. Both less expensive than any electrical component failure