Thread: Modern Jumper Leads

Originally Posted by drivesafe

Next, connect the positive lead to the crippled vehicle's positive ( + ) battery terminal, then connect the other end of the positive lead to the donor vehicle's positive ( + ) battery terminal.

Then connect one end of negative lead to the donor vehicle battery's ( - ) negative terminal.

Now find a suitable earthing point in the crippled vehicle's engine bay ( if the cranking battery is located there ). This earthing point should be a bolt or something of that nature.

As the positive is the first lead being connected I can't see how it matters which battery is connected first.

As for the negative, I know that the last connection should be done to the motor and not the battery, for explosive reasons, but for 40 plus years I have been going direct to the battery terminal with out a problem.

If you are stuck and have an 18 volt cordless drill in the car you can jump start off it if the drill battery is well charged.

Originally Posted by p38arover

My jumper leads are Michelin Smart Jumper leads and are non-polarised so anyone can use them with worrying about connections.

They supposedly have spike suppression built in.

Michelin Smart Jumper cables for easier jump-starts - CNET

Well these are $50, apparently they don't work if the crippled car battery is too low on voltage, as you need the two green led lights on, for it to work. If the crippled car battery is too low on voltage then you need the old style jumper leads, apparently.


They seem to be heavy duty and heavy guage according to the reviews. If it were deemed the correct decision to get a set with a surge protector this might be the one.

Hi Dave ( d2dave ) and yes, it makes no difference as to which vehicle you connect the positive jumper lead to first.

But it is essential that the last connection is that of the negative jumper lead in the crippled vehicle and this MUST NOT be connected to the negative ( - ) terminal of the crippled vehicle's cranking battery because, depending on how the battery went flat, there can be a very high risk of hydrogen gas being present at the disabled vehicle's cranking battery.

Much better to be safe than harmed.

On another point, and islandnomad, answering your question about surge/spike "protected" jumper leads.

The only advantage they offer, is to line the pockets of the sellers of these con jobs.

Now just think about these scenarios.

So you have a set of spike protected jumper leads and they are "THEORETICALLY" designed to protect one vehicle from spikes coming from the other vehicle.

So if the donor vehicle causes a spike and the spike protection in the leads protects the crippled vehicle, why is the donor vehicle not damaged.

And the reverse is also the same case.

The problem is that people can have electronic faults with their disabled vehicle after jump starting and immediately blame the problem on MYTHICAL spikes coming from the donor vehicle.

While vehicles often have some form of problem when their motor is finally started after a jump start, but the problems are caused before the donor vehicle is even asked for, let alone connected to the crippled vehicle.

What actually happens is, you come to your vehicle, not knowing the cranking battery is on it's last legs.

You press your remote and the vehicle responds, waking up the computers.

You then get in and try to start your motor. This is where the problems are caused and it's not because of mythical spikes, it is actually the exact opposite.

When you press your remote and wake up the computers in your vehicle, they begin to go through their startup processors and at this point in time, there is usually enough energy in the battery to allow these startup processors to begin.

You then get in and try to start your motor, but the instant the starter solenoid links the starter motor to the cranking battery, any remaining energy in the cranking battery is pretty well instantly used up and the battery voltage drops to a very low level, and 5v is not uncommon.

At that very moment, your computers were still going through the startup processors and are suddenly starved of power and end up corrupted when the power is finally returned.

But you are no longer trying to start the motor and it is not until you have completed a successful jump start that you find you have "SPIKE" caused problems in your electronics.

These same SPIKE caused problems usually clear themselves once you have a new or fully charged battery, and you turn the vehicle off.

When you turn most new vehicles off, the onboard computers go through a shutdown mode and then when you go to start the vehicle again, these onboard computers then automatically reboot them selves.

The Spike damage is suddenly no longer there.

Another suggestion with jumper leads. Most leads usually have the cable connected to the clamp with just a crimp.
When they get old resistance can build up at this point. This is why sometimes they get a bit hot after using them.

When ever I purchase a new set of leads the first thing I do is solder this joint.
I have had old leads go from not working very well to working fantastic after doing this.

Originally Posted by d2dave

As the positive is the first lead being connected I can't see how it matters which battery is connected first.

Hi again d2dave and sorry it was late last night when I replied to your post.

Yes you can connect the positive jumper leads to either vehicle first.

BUT!

By getting into a routine of connecting the positive jumper lead to the crippled vehicle's cranking battery ( + ) terminal first, you then go to the donor vehicle and connect the other end of the he positive jumper lead to the donor vehicle's cranking battery positive ( + ) terminal next.

By following this part of the procedure in this order, you are now instinctively set up to make the first connection of the negative jumper lead in the correct order. To the donor vehicle's cranking battery's negative ( - ) terminal first.

Again, this will then automatically make the last connection, the connecting of the other end of the negative jumper lead, in the correct and safest mannor.

It looks like me and drive safe are going to have differing opinions on this one...

I dont recommend hooking up with the donor vehicle running.

the other thing I recommend doing is (and this only applies if you have one) is using your axillary battery if its suitable for jump starting from.

While I have access to plenty of cable (plus a set of crimpers for eye terminals) but can't find a decent set of spring clamps for the ends. Does anyone have a recommendation on who/where has the best? Either with a good crimp or preferably a bolt for an eye terminal as I can fit these without issue (if anyone needs batt leads crimped the crimper is available to use)

Originally Posted by Blknight.aus

It looks like me and drive safe are going to have differing opinions on this one...

I dont recommend hooking up with the donor vehicle running.

the other thing I recommend doing is (and this only applies if you have one) is using your axillary battery if its suitable for jump starting from.

I have been planning to fit a heavy cable and a battery isolator switch between the two battery + terminals to be able to start from the aux.
The - is common to both batts.
My aux bat is also charged from the solar panels via a Ctech dual.