Waldo   96 #1 Posted January 7, 2016 When jump starting a car; why does it matter what order you attach the jump cable clamps in?  They say, use the following order:  1. Red clamp to positive on good battery. 2. Other red clamp to positive on bad battery. 3. Black clamp to negative on good battery. 4. Other black clamp to exposed metal bolt on bad car (away from fuel).  Is that right?  What happens if you get the order wrong? What happens if you attach black clamp (see '4' above) to negative on the bad battery, rather than ground on bad car?  Thanks. Share this post Link to post Share on other sites Share this content via...
truman   10 #2 Posted January 7, 2016 (edited) With respect to 4 ..I think they advise to attach to the body work away from the battery/fuel is so that any spark you may generate from completing the circuit won't ignite any gas which may be leaking from the battery or any petrol vapour? Maybe a bit out of date now that most batteries are "sealed"..not sure why the connection order makes much difference.. Edited January 7, 2016 by truman Share this post Link to post Share on other sites Share this content via...
L00b   441 #3 Posted January 7, 2016 The way I've always done it myself, and observed it:  Red first, black next = no sparks at either black end.  Black first, red next = sparks at both red ends. Share this post Link to post Share on other sites Share this content via...
Waldo   96 #4 Posted January 7, 2016 Thanks Truman.  Point 4 is nothing to do with it draining the battery on the good car?  It's also, not always clear where there is any exposed metal. How about a bolt that attaches a front light cover to the car chassis; would that qualify? There were also some rusty looking bolts, which I avoided as they may not conduct electricity so well, I guess. Share this post Link to post Share on other sites Share this content via...
RonJeremy   10 #5 Posted January 7, 2016 All a bit too "elf and safety". Jus get on with it but don't touch the two clamps together. Share this post Link to post Share on other sites Share this content via...
DnAuK   10 #6 Posted January 7, 2016 I listen regularly to a programme called Car Talk from the US (even though one of the hosts died recently and they are now broadcasting repeats). Wonderful show. Highly recommended for entertainment purposes even if you're not that into cars. You can get each weekly show on podcast.  Now this question came up regularly, especially from people with electrical engineering backgrounds who claim that an open circuit is an open circuit no matter which end is opened first. But apparently this is dead wrong. Sometimes quite literally!  Apparently you should always connect the jumper cables in the order described below: •Connect one red clamp to the positive (+) terminal of the dead battery. •Connect the other red clamp to the positive (+) terminal of the good battery. •Connect one black clamp to the negative (-) terminal of the good battery. •Connect the other black clamp to a piece of grounded metal on the dead car, preferably the bolt where the thick negative cable from the battery connects to the chassis. If this is not practical, look for shiny metal (not painted or oily) that is attached to the engine. Usually a nut, bolt or other protruding shiny metal will work. You may see a small spark when you connect to a good ground. As a last resort, you may connect to the negative (-) post of the dead battery, but this risks igniting hydrogen gas coming off the battery. •Make sure none of the cables are dangling into the engine compartment, where they could be exposed to moving parts. Share this post Link to post Share on other sites Share this content via...
Waldo   96 #7 Posted January 7, 2016 It's just all about avoiding sparks then? Share this post Link to post Share on other sites Share this content via...
truman   10 #8 Posted January 7, 2016 Thanks Truman. Point 4 is nothing to do with it draining the battery on the good car?  It's also, not always clear where there is any exposed metal. How about a bolt that attaches a front light cover to the car chassis; would that qualify? There were also some rusty looking bolts, which I avoided as they may not conduct electricity so well, I guess.  Won't make a difference to the battery 'cos the -ve terminal is (usually) connected to the bodywork (don't know if it'd work on a TVR ) To be honest I've usually just connected to the battery posts..and I'm still here to tell the tale.. Share this post Link to post Share on other sites Share this content via...
Resident   1,195 #9 Posted January 7, 2016 Won't make a difference to the battery 'cos the -ve terminal is (usually) connected to the bodywork (don't know if it'd work on a TVR ) To be honest I've usually just connected to the battery posts..and I'm still here to tell the tale..  I've always connected battery to battery like yourself. Share this post Link to post Share on other sites Share this content via...
ivan edake   13 #10 Posted January 7, 2016 I listen regularly to a programme called Car Talk from the US (even though one of the hosts died recently and they are now broadcasting repeats). Wonderful show. Highly recommended for entertainment purposes even if you're not that into cars. You can get each weekly show on podcast. Now this question came up regularly, especially from people with electrical engineering backgrounds who claim that an open circuit is an open circuit no matter which end is opened first. But apparently this is dead wrong. Sometimes quite literally!  Apparently you should always connect the jumper cables in the order described below: •Connect one red clamp to the positive (+) terminal of the dead battery. •Connect the other red clamp to the positive (+) terminal of the good battery. •Connect one black clamp to the negative (-) terminal of the good battery. •Connect the other black clamp to a piece of grounded metal on the dead car, preferably the bolt where the thick negative cable from the battery connects to the chassis. If this is not practical, look for shiny metal (not painted or oily) that is attached to the engine. Usually a nut, bolt or other protruding shiny metal will work. You may see a small spark when you connect to a good ground. As a last resort, you may connect to the negative (-) post of the dead battery, but this risks igniting hydrogen gas coming off the battery. •Make sure none of the cables are dangling into the engine compartment, where they could be exposed to moving parts.  This is correct,also when you remove the leads always remove the negative lead first.Doing it this way ensures you never remove or fit the live positive lead when the two cars are connected together with the negative earth lead..If you did do it the other way round and accidently caught the bodywork of either car with the live positive lead it would cause a spark which could ignite fuel vapour.In a worse case scenario the spark could be powerful enough to weld the lead to the body and this can cause the battery to explode. Share this post Link to post Share on other sites Share this content via...
convert   10 #11 Posted January 7, 2016 Won't make a difference to the battery 'cos the -ve terminal is (usually) connected to the bodywork (don't know if it'd work on a TVR ) To be honest I've usually just connected to the battery posts..and I'm still here to tell the tale..  Most TVR's actually have an anderson connector for jump starting.  Mine is too old for that do it's just battery to battery.  Live cable first, the neg cable - car first then good battery. Share this post Link to post Share on other sites Share this content via...
El Cid   221 #12 Posted January 7, 2016 I've always connected battery to battery like yourself.  Me too. Why not connecting to the body of the cars for both negatives? Share this post Link to post Share on other sites Share this content via...