↓ Advertise on Defender2 ↓

Home > Off Topic > Using jump leads correctly.
Post Reply  Down to end
Page 1 of 2 12>
Print this entire topic · 
Bluest



Member Since: 23 Apr 2016
Location: Lancashire
Posts: 3995

United Kingdom 2007 Defender 110 Puma 2.4 XS CSW Java Black
Using jump leads correctly.
I’ve had a few ropey old motors in my life and have need of a jump start on more than one occasion. I’ve alway connected jump leads between batteries with no problems. However someone recently gave me a new set of leads and the instructions explicitly warn against connected to the negative terminal on the battery of the stranded vehicle. Doesn’t really explain why though. A bit of Googling gives similar advice, saying the black lead should go to an earth point other than the battery.

Have I been doing it wrong all these years? 2007 110 TDCi Station Wagon XS
Post #679830 19th Jan 2018 9:53am
View user's profile Send private message View poster's gallery Reply with quote
ian series 1



Member Since: 17 Nov 2014
Location: south
Posts: 3127

United Kingdom 2008 Defender 90 Puma 2.4 CSW Bonatti Grey
as far as I’m aware, it was just down to keeping any sparks away from the battery?

You will find on most modern vehicles now the battery is out of sight, and you just have the jump terminals in a convenient location.

Like you, been jumping cars and trucks for years using the “old fashioned” way :lol
But always good if you can keep the sparks to a minimum. Thumbs Up 80" 80" 86" 88" 90"

Wanted, Forward Control Anything considered.
Post #679831 19th Jan 2018 10:00am
View user's profile Send private message View poster's gallery Reply with quote
blackwolf



Member Since: 03 Nov 2009
Location: South West England
Posts: 16856

United Kingdom 2007 Defender 110 Puma 2.4 DCPU Stornoway Grey
I believe that the reasoning behind this advice is that the final connection is likely to spark, and that the battery may be gassing, in which case - BOOM! I know many old-school types (myself being one) who did it carefully this way for years without causing an explosion*, but it is undoubtedly safer to make the final connection well away from anything combustible.

I have only once been present when a lead-acid battery has exploded, and it is quite startling. It was an old Volvo-BM wheeled loader which I was starting on a very cold morning, and for some reason I have never quite figured out, there must have been a spark at the battery when I cranked the starter. Fortunately I was standing on the other side of the machine to the battery, because about 60% of the battery simply disappeared, much of it never to be seen again, with other fragments travelling about 30 yards, and of course everything was dripping in sulphuric acid. I shudder to think what would have been the outcome for me if the button on the starter solenoid had been on the same side of the motor as the battery.

Ever since then I have been a lot more careful with lead-acid batteries.





*Technically I suppose it would actually be a deflagration, but the result would be the same - BOOM!


Last edited by blackwolf on 19th Jan 2018 10:03am. Edited 1 time in total
Post #679832 19th Jan 2018 10:02am
View user's profile Send private message View poster's gallery Reply with quote
discomog



Member Since: 09 May 2015
Location: Notts/Lincs Border
Posts: 2494

United Kingdom 2015 Defender 90 Puma 2.2 XS CSW Santorini Black
After you have connected the positive leads to both batteries you should then connect the negative lead to the other cars battery and then make the final connection to a metal earth on your car. This way it avoids any arcing at the battery which could cause an explosion. Defender 90XS SW
Mini Countryman Cooper S
Morgan Plus 8
Post #679833 19th Jan 2018 10:03am
View user's profile Send private message View poster's gallery Reply with quote
discomog



Member Since: 09 May 2015
Location: Notts/Lincs Border
Posts: 2494

United Kingdom 2015 Defender 90 Puma 2.2 XS CSW Santorini Black
Blackwolf beat me too it. He's obviously faster at typing than me Bow down . I've also witnessed a battery explode and you certainly wouldn't want to be stood over it when it goes bang. Defender 90XS SW
Mini Countryman Cooper S
Morgan Plus 8
Post #679834 19th Jan 2018 10:05am
View user's profile Send private message View poster's gallery Reply with quote
blackwolf



Member Since: 03 Nov 2009
Location: South West England
Posts: 16856

United Kingdom 2007 Defender 110 Puma 2.4 DCPU Stornoway Grey
And ian series 1 beat me to it!

However there is at least consensus - we all agree the reason is to reduce the risk of blowing yourself up!
Post #679864 19th Jan 2018 11:31am
View user's profile Send private message View poster's gallery Reply with quote
Mdm



Member Since: 11 Sep 2013
Location: Sunny Lancashire
Posts: 1523

United Kingdom 
this advice mainly refers to newer vehicles that have specific jump start points.

most modern vehicles have small fuse-links or similar that in the event of a crash disconnect the battery. to prevent fires etc.

its as well as the fuel cut off reset button on the bulkhead. if memory serves me its linked to airbag deployment and if the car rolls etc.
Post #679865 19th Jan 2018 11:33am
View user's profile Send private message View poster's gallery Reply with quote
Bluest



Member Since: 23 Apr 2016
Location: Lancashire
Posts: 3995

United Kingdom 2007 Defender 110 Puma 2.4 XS CSW Java Black
Thanks all, I shall update my risk assessment, write myself a briefing note and adopt this newfangled approach Very Happy

On a serious note, given the unusual location of a defender battery, where would one recommend clipping the back cable on a Puma? I guess popping the bonnet and finding something on the engine is best. 2007 110 TDCi Station Wagon XS
Post #679867 19th Jan 2018 11:36am
View user's profile Send private message View poster's gallery Reply with quote
Procta



Member Since: 04 Dec 2016
Location: Sunderland
Posts: 4932

United Kingdom 
from what I watched on a youtube, is that if put the earth on to the engine or gearbox, makes a full blown circuit or something, rather than just battery to battery. Not sure how right that is mind, I have always put battery to battery. Defender TD5 90 ---/--- Peugeot 306 HDI hatch back

Success is 90% Inspiration and 4 minutes Preparation # you can make it!
Post #680140 20th Jan 2018 1:43pm
View user's profile Send private message View poster's gallery Reply with quote
custom90



Member Since: 21 Jan 2010
Location: South West, England.
Posts: 19525

United Kingdom 
This is why the battery has a breather in the first place.

The only reason in my view is to avoid sparks in the battery vicinity but, choose the wrong chassis earth area then you are going to have extremely high resistance. Diesels Lives Matter. ⛽️🛢️👨‍🔧🧰⚙️
And if You Love the Country, then we’re on the same side ~
I got’ love for Britain, I got’ British pride’. 🇬🇧
Post #680153 20th Jan 2018 2:58pm
View user's profile Send private message View poster's gallery Reply with quote
JWL



Member Since: 26 Oct 2011
Location: Hereford
Posts: 3443

England 2002 Defender 110 Td5 SW Coniston Green
Even better is to have an Anderson connector accessible on your Defender. Incidently I had to jump start a neighbours car tonight, so much easier to connect the leads to his battery and then stand by my bumper and plug the Anderson connector in Wink
Post #680267 20th Jan 2018 9:15pm
View user's profile Send private message View poster's gallery Reply with quote
HardCharger



Member Since: 03 Mar 2013
Location: Manila, SFO, Amsterdam
Posts: 673

2011 Defender 110 Puma 2.4 SW Stornoway Grey
If the battery is under the bonnet, it's easy to find a metal bit for the negative (earth) connection, in Defenders however, where do we connect them? Or are we to do direct connections when jumping starting Defenders?

Going the other way around is not a problem though. (Defenders jumpstarting other vehicles)
Post #736597 25th Oct 2018 2:58am
View user's profile Send private message View poster's gallery Reply with quote
mick



Member Since: 08 Feb 2010
Location: Yorkshire
Posts: 2109

England 2010 Defender 130 Puma 2.4 HCPU Rimini Red
A lot of modern cars like the Discovery 4 have an eco attached to the earth lead and if you attach a charger or external battery it can Censored it up.
Post #736717 25th Oct 2018 5:45pm
View user's profile Send private message View poster's gallery Reply with quote
williamthedog



Member Since: 29 Dec 2012
Location: south wales
Posts: 3441

2011 Defender 90 Puma 2.4 PU Tamar Blue
HardCharger wrote:
If the battery is under the bonnet, it's easy to find a metal bit for the negative (earth) connection, in Defenders however, where do we connect them? Or are we to do direct connections when jumping starting Defenders?

If you put a tail lead with a anderson plug on it takes the chance of a explosion away from the battery. Obviously you need a anderson plug on the one end of the jump leads Thumbs Up
Post #736799 25th Oct 2018 10:35pm
View user's profile Send private message View poster's gallery Reply with quote
HardCharger



Member Since: 03 Mar 2013
Location: Manila, SFO, Amsterdam
Posts: 673

2011 Defender 110 Puma 2.4 SW Stornoway Grey
So that's the safer way to do it then. Thanks, williamthedog.

In the meantime, direct to battery is my only option then?
Post #736805 26th Oct 2018 2:02am
View user's profile Send private message View poster's gallery Reply with quote
Post Reply  Back to top
Page 1 of 2 12>
All times are GMT + 1 Hour

Jump to  
Previous Topic | Next Topic >
Posting Rules
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum



Site Copyright © 2006-2024 Futuranet Ltd & Martin Lewis
DEFENDER2.NET RSS Feed - All Forums