Jump starting a vehicle

[Anonymous Poster]

Gary, I've encountered this exact situation myself, twice.
One time it was a frozen dead battery on a tractor. When I hit the switch on the startall the tractor started about half a second before the battery EXPLODED. I was very happy the Startall had 18' cables.
The second time I encountered the situation, the battery being jumped had an internal short ( one cell had collapsed) and effectively became an electric heater, absorbing all available current coming thru the jumpers. In that case, it was a standby generator that was needed immediately, so I pulled the + cable from the genset and started the machine using the battry at the end of the jumpers to get and keep the genset running.
I've learned a number of expensive lessons over the years about jump starting.
First, always disconnect the alternator on the running vehicle doing the jumping. This prevents alternator damage when powering a large vehicle from a smaller one. A 580 Case will destroy the alternator in a Duster when the 580 comes to life.
Second, always check the electrolyte in the battery that is being jumped, low or frozen electrolyte will cause BIG problems.
Third, Hook up to the dead vehicle first, then +, and finally frame (not battery post) on the jumping vehicle.
Test your connection by pulling the headlights on (dead vehicle). No lights indicate either a bad connection, or dangerous situation.
Turn headlights off, and allow dead battery to charge for a minute before trying to start.
Jumping a dead battery is always a dangerous situation. If the battery has an internal defect, you are creating Hydrogen Gas in a container where a spark may occurr, as well as steam. That's exactly what happened in a place called Chernobyl about 20 years ago, and while yor results may be smaller, they won't be any less devistating if you're standing next to the dead battery.

 

[Gary_in_Indiana]

<font color=blue>"I think the correct way to jump a vehicle is to make the final connection to the car giving the jump and then not to the negative side of the battery."</font color=blue>

I don't think that's exactly right. I believe you've got the right idea but the wrong vehicle.

What I've always understood the correct sequence to be is

1) Dead battery positive
2) Live battery positive
3) Live battery negative
4) Ground point AWAY from dead battery on that vehicle.

That way, when you make the final connection, any sparks created are away from any flammable gases from the dead battery and explosions such as those mentioned can be avoided.

 

[Gary_in_Indiana]

Chim,

I remember that post of yours and wholeheartedly agree. I have very good clamps on very good cables but maybe the vicegrips are something to consider. Any chance you could post a picture of how you connected your cable to one? Thanks! /w3tcompact/icons/smile.gif

 

[Bird]

Nope, Gary, Jeff was right. And while I've never personally had any kind of problem jump starting vehicles (and I've sure done a lot of it), one of my employees had a battery blow up in her face several years ago; just sheer luck that she had no serious injuries.

 

[chim]

I used mechanical lugs and fastened them to the adjusting bolts on the visegrips. The local hardware store has a good selection of nuts, and the lugs are readily available at an electrical supply house (mebbe even Home Depot). One of the nice things about this setup is the ability to get a great connection on side-terminal batteries. They are also good for getting a connection to the vehicle frame, or to a bracket attached to the vehicle engine to avoid connecting the ground to the battery (as some posters cautioned about). See attached pic.

EDIT: I know it doesn't need mentioned, but exercise care when using these. The visegrips are big conductive thingys. You can guess what would happen if you try to clamp to the "+" terminal of (especially) the good battery while the visegrip is contacting the car body..........chim

 

[JimMc]

You don't have to be jump starting to have problems. Once, immediately after having Sears install a new battery, my wife went out to pick up her car from the Sears Service Dept. The car wouldn't start so she called me. I was wiggling the positive cable to see if Sears had forgotten to tighten it. Meanwhile, the wife decides to try it one more time. The resulting spark ignited the battery gases, blowing the new battery up in my face. BTW, Sears didn't even offer to replace my new shirt which immediately started turning all sorts of colors, although they did give me a paper towel to wipe the acid from my face. Only after moving the discussion to the waiting room in front of a lot of customers did they even agree to replace the battery. One on one in the service bay, they were going to make me buy another one.

 

[BigDave]

Gary,

O.K., my two cents. Even if you removed the battery from the dead vehicle and connected the cables to the leads, the dead car, it will start everytime IF AND ONLY IF your jumper cables are sufficiently thick enough to carry the high current load over the length of your cables. I learned this when I needed a friend to jump start my truck, my cables wouldn't even turn my starter, but his much heavy cables allowed my truck to start right up.

 

[chim]

...........and in the days before alternators, it would've kept running after you disconnected the cables. What a shock it was for us kids not to be able to start a dead car by pushing it and popping the clutch when generators went away. (Had a flashback about residual magnetism in the generator)..........chim

 

[Gary_in_Indiana]

Bird,

This could well be the first time I've disagreed with you. As I said earlier, I grew up the son of a mechanic and couldn't imagine having been taught wrong but, given your history of accuracy, I thought I'd better check.

According to a number of sources online found through a google search for "jump starting battery" my sequence of connections is correct.

The American Automobile Association (AAA), for one, lists the following steps in order.

"Connect the positive (+) terminal of the discharged battery to the positive (+) terminal of the booster battery, using the positive jumper cable.

"Connect one end of the negative (-) jumper cable to the negative (-) terminal of the booster battery.

"WARNING: Do not connect the negative (-) jumper cable directly to the negative (-) terminal of the discharged battery. A spark may occur when the cable is connected or disconnected that could ignite hydrogen gas escaping from the battery and cause an explosion.

"Connect the second end of the negative (-) jumper cable to a known good ground on the car being jumped. The vehicle frame or engine block are good examples. Some vehicles have special ground terminals in the engine compartment, labeled for use in a jump-start."

There were any number of other sources listing the same sequence, so I'll have to stand by what Dad taught me over 35 years ago. /w3tcompact/icons/smile.gif

 

[Bird]

My apologies, Gary. You're obviously correct in what AAA and the National Safety Council are recommending. I was taught many years ago that a weak or defective battery was more likely to produce gas that a spark could ignite than a good battery, hence the recommendation to make the final connection at the vehicle with the good battery (and thought that was the National Safety Council's recommended way, but I see now theirs is the same as the AAA). You reckon my old memory's failing me?/w3tcompact/icons/frown.gif

Apparently Jeff learned the same way I did and <A target="_blank" HREF=http://www.salemboysauto.com/faqs/faq-28.htm>this link</A> also teaches our way, but yours is definitely in the majority./w3tcompact/icons/laugh.gif Actually, I think it doesn't make a lot of difference as long as the final connection is made away from the battery so that any spark will not be near either battery.