 | Home > Off Topic > Using jump leads correctly. |
 
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| Cupboard Member Since: 21 Mar 2014 Location: Suffolk Posts: 2971   
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If you connect the Defender end first then connect the other car end to something away from the battery that solves the problem.
I have actually jumped a car from my Defender and I did pop the bonnet to find an earthing point, although that was only once and I've done it the lazy way far more. The much more important thing is to always connect the negative lead last and disconnect the negative lead first - if you connect the negatives then drop a positive on something grounded then bad things will happen. If you connect the positives then drop a negative on something grounded then nothing will happen. This is especially of note in cars with batteries that are a fiddle to get at. Edited because I typed it wrong  Thanks blackwolfLast edited by Cupboard on 26th Oct 2018 10:55am. Edited 1 time in total |
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26th Oct 2018 7:48am |
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| ARC99 Member Since: 19 Feb 2013 Location: North Yorkshire Posts: 1831 
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I read somewhere years ago probably in an article connected to caravans, that it only the connection of the earth that causes a spark and that the earth should always be connected first. Don't make old people mad.
We don't like being old in the first place, so it doesn't take much to  us off.
Richard |
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26th Oct 2018 8:04am |
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| HardCharger Member Since: 03 Mar 2013 Location: Manila Posts: 740  
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Copy that.
So, how do we manage to jump start a Defender? |
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26th Oct 2018 8:08am |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17462 
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I think you meant to say "connect the negative lead last and disconnect the negative lead first". This will be correct provided that the vehicles concerned are both negative earth, which will be the case with almost all modern vehicles. Old vehicles may be positive earth or even, in the case of very old vehicles (and a few very specialised vehicles) wired return, i.e., no earth. It would be more generally true therefore to say that the lead between the earthed terminals should always be the last connection made and the first broken. If you are jumping a positive earth vehicle from a negative earth vehicle or vice versa it reall doesn't matter which you connect first or last, but the last connection made (and first broken) should be to an earthing point (not the battery if possible) on either vehicle. If you are jumping a wired return vehicle, the last connection made (and first broken) should be to an earth point on the earth return vehicle.
Not true. It is the last connection to be made which will spark, i.e., the one that completes the circuit, which should, in most cases, be an earth connection. However if you have connected the earth lead first, you'll get a spark from the non-earth lead. This can be dangerous since it is probably a battery connection and therefore increases the risk of a hydrogen explosion. Be aware that the battery on a Defender, provided that it is either the original factory-fitted battery or an direct equivalent, has a remote vent pipe for an hydrogen which may gas off. It should therefore be quite safe to connect to a battery terminal since any gas is vented under the seat box. |
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26th Oct 2018 10:09am |
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| Cupboard Member Since: 21 Mar 2014 Location: Suffolk Posts: 2971
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Thanks blackwolf, you're completely correct I made a cockup. Corrected now
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26th Oct 2018 10:56am |
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| HardCharger Member Since: 03 Mar 2013 Location: Manila Posts: 740
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Thanks for the clarification, Blackwolf!
I think I may be missing that vent tube, time to check with the parts suppliers again. Where does one normally find the vent hole in the battery? And since it appears that I have no vent tube at the moment, where does it exit? |
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27th Oct 2018 4:34am |
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| williamthedog Member Since: 29 Dec 2012 Location: south wales Posts: 3441 
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All depends what battery you have fitted. If its a sealed battery then it probably won't have a vent fitted.
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27th Oct 2018 7:05am |
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