Thread: Jump Starting - negative terminal or body earth?

I use BOTH the +ve and -ve terminals on the actual Starter Motor, 1. least resitance (eg low volt drop) and 2. its well away from the battery.

Originally Posted by dick180641

I use BOTH the +ve and -ve terminals on the actual Starter Motor, 1. least resitance (eg low volt drop) and 2. its well away from the battery.

Whether this is feasible depends on the vehicle.

To take my two Landrovers as an example, on the County, the battery terminal is so close to the chassis that putting a jumper lead on it is very risky (and you would have tto connect it lying on your back under the vehicle. On the 2a, you do not want to put the jumper lead on it because the solenoid is remote from the starter - and the solenoid is totally inaccessible to jumper leads, on the firewall behind the engine.

My tractor would be easy starter is easily accessible. But where it lives that side is inaccessible to a vehicle - if I had longer leads, they could be brought across under the tractor.

On a similar subject, when connecting or disconnecting a battery, always connect or disconnect the earth side last. This is because if you do this, there is no risk of your spanner shorting when doing up the live terminal because it is not live until the earth is connected, and when doing up the earth terminal it doesn't matter if the spanner hits the carrier or body since it is at earth potential anyway.

John

Originally Posted by JDNSW

On a similar subject, when connecting or disconnecting a battery, always connect or disconnect the earth side last.

Almost there.

Disconnect all battery negative ( - ) terminals first.

Reconnect all battery negative ( - ) terminals LAST.

for the more adventurous out there
got a spare battery but no jumper cables?

hold the spare battery upside down and hold it agasint the flat battery. same as normal, +ve to +ve, -ve to -ve.


ive only tried this with a sealed battery.

Remember, this is a Land Rover forum. For more than the first 15 years of production, Land Rovers were positive earth.

Aaron

Originally Posted by Aaron IIA

Remember, this is a Land Rover forum. For more than the first 15 years of production, Land Rovers were positive earth.

Aaron

Beat me to it - actually 1948-1966 = 18 years.

And from the first fitting of electrical systems to cars in the Edwardian period, until the 1950s, both positive and negative earth were used, with probably a majority using positive earth after about 1930, as coil ignition became almost universal, for good theoretical reasons at least (better spark), although the difference is usually insignificant in practice (a spark is easier to initiate if the hot electrode is the one supplying electrons, and this is automatically provided with standard Kettering ignition and positive earth)

With this in mind, earth first off/last on is probably a better all round motto than negative first off/last on, at least on this forum.

John

Beat me too. I had a car once which was positive earth, but I can't remember which one.

I have been really surprised by all the posts on this. Maybe I have been blissfully unaware but I have merrily jump started countless batteries with no ill effects and always connected to both terminals of the battery.

Somewhere along the line I heard about new car sensitivities and bought a good set of jumper leads with a circuit breaker or surge protector (not sure which) and still have the old ones as well (they are a lot more heavy duty - our old farm equipment is a bit before everything got a bit politically and electrically sensitive).

In all honesty, is connecting the negative earth that important? Don't the tyres mean it isn't really grounded? Or is this about how the circuit isn't completed and there fore a surge can't occur?