Correct procedure for disconnecting Batteries

[mel s]

Originally Posted by t55watson

If you touch the red cable to the positive post when the black cable is connected you will get a spark. Sometimes a BIG spark. This introduces the possibility of big BANG from the gasses that are given off of a battery.

Originally Posted by Ray,IN

Tony stated it correctly. I had to re-read his post 3 times to clarify myself as to what he actually said.

t55watson & Ray,IN
The statement "If you touch the red cable to the positive post when the black cable is connected you will get a spark. Sometimes a BIG spark" is true/correct.

However it is also true "If you touch the black cable to the negative post when the red cable is connected you will get a spark. Sometimes a BIG spark".

Mel
'96 Safari

[BFlinn181]

It's also true that a battery that has been at rest for a winter unconnected and charged up will be fine. Add a charger during long time storage and you have the possibility of over-charging it or boiling it dry. As a teen I worked in a marina where we would pull and store over 50 batteries and once charged and checked for electrolyte levels, they remained un-connected and untouched from October to April or May.

Back in Post #11 twinboat mentioned that a battery at rest won't be outgassing dangerous levels of hydrogen. If you've been cranking the starter or had it on a fast charger, large amounts of hydrogen gas can build up. It's something to always keep in mind, but it's normally not a dangerous thing to disconnect or hook up a battery. If you are still concerned or afraid, disconnect the other end of the ground cable, connect to the battery, then reconnect the cable and make the circuit complete away from the battery. You could also just pull the large, 80-120 amp master fuse to open the circuit if you are sure the battery isn't connected by secondary wires.

[530ktm]

Originally Posted by twinboat

Standard practice is to remove or connect the negative first for the reasons mentioned.

I have always removed the negative first and put the negative on last. If you have the negative attached first and you touch something metal while attaching your positive you are going to get yourself a surprise. YMMV

[Ray,IN]

Originally Posted by 530ktm

I have always removed the negative first and put the negative on last. If you have the negative attached first and you touch something metal while attaching your positive you are going to get yourself a surprise. YMMV

Never done that, but saw it happen, and never forgot the sight. A friend connected the neg first, when he attempted to tighten the pos clamp the wrench touched something metal. His wedding ring got hot enough to severely burn his finger almost to the bone before he could get to water. Can't happen when the neg is attached last.