Thread: Which Car Battery Terminal to Connect First

No need, just positive first then negative.

The small spark is fine, as long as no gases around!

Connect positive first, as any accidental touching with the spanner will be harmless, on both terminals.

Hi Lionel, as Tombie posted, you will be fine but just for future reference.

When you need to work on vehicle batteries, before you remove any cable/terminals, first make sure the vehicle's computers have finished shutting down.

With new Land Rovers, this is indicated by the PARK BRAKE light on your dash.

When you first turn off your ignition, all dash lights and indicators will also turn off at the same time "EXCEPT" the PARK BRAKE light.

The PARK BRAKE light can remain on for up to 3 minutes, and this indicates that your on-board computers are still going through their Shot-Down sequences.

If you disconnect your battery before the on-board computers have finished going through their Shot-Down sequences, it is highly "UNLIKELY" that you will do any damage, but you may get some unwanted warnings next time you start your motor.

If you do forget and disconnect early, and then get some warnings next time your start your motor, just turn your ignition off, lock your vehicle, and wait till PARK BRAKE light goes out.

Now you can start your vehicle and all should be well. All new vehicles perform a REBOOT process when either starting and/or turning off the ignition.



With the on-board computer Shot-Down sequences finished, now you can disconnect the battery(s).

With a single battery setup, as in most vehicles, remove the NEGATIVE ( - ) cable/terminal first, then you can safely do what ever work you need to do to the vehicle's electrics.

Unless you are going to actually work on the cranking battery, you do not have too disconnect the POSITIVE ( + ) cable/terminal.

If you need to remove the cranking battery, then always remove the NEGATIVE ( - ) cable/terminal first, then disconnect the POSITIVE ( + ) cable/terminal.

Where there is more than one battery in a vehicle, you should disconnect the NEGATIVE ( - ) cable/terminals from ALL batteries first, then you can safely work on which ever battery you need to.

When you have finished working on your vehicle's batteries and/or electrics, connect the POSITIVE ( + ) cable/terminal on each battery first.

Then the last thing should be to connect all the NEGATIVE ( - ) cable/terminals.

It is commonplace to get a spark, as you connect NEGATIVE ( - ) cable/terminals.

if you're worried about the spark causing damage, grab a 21w light in a cabled holder connect one end to the earth cable, the other to the battery post and then slide the clamp onto the post after the light goes out. (assuming youve already connected positive first.

Originally Posted by Tombie

No need, just positive first then negative.

The small spark is fine, as long as no gases around!

Not just battery gases, I was talking to a hazardous area expert and he said you only need a couple of cars, a boat and a lawnmower (or rather the fuel for) in your garage and it technically became a hazardous area IIRC.

Originally Posted by RANDLOVER

Not just battery gases, I was talking to a hazardous area expert and he said you only need a couple of cars, a boat and a lawnmower (or rather the fuel for) in your garage and it technically became a hazardous area IIRC.

Sounds familiar to our QPs here.

Hence the sites have a No Petrol policy. Diesel or nothing.

I amused our safety team when they did a “is your home safe” campaign a while back. Seems I’m the only person across our business with a flammables locker at home!

Just an addition to the above - the first terminal to remove is the earth terminal, which is not necessarily the negative, although it will be for any new vehicles and for nearly all made since 1970 of a little earlier.

However, this being a Landrover forum, with vehicles going back to 1948, there are a significant number that have the battery connected positive to earth.

All Landrovers prior to 1967 left the factory this way, although quite a few of these have since been converted to negative earth. (For compatibility with modern accessories or because a modern alternator has been fitted.

Regardless of the polarity, always disconnect the earth side of the battery first.

Agree John, my old David Brown tractors are positive earth.

Made in England.