replace battery order

In the battery instructions, it gives this order:

1. disconnect negative terminal on dead battery
2. disconnect positive terminal on dead battery
3. replace with new battery
4. connect positive terminal to new battery
5. connect negative terminal to new battery

Anyone know the reason for disconnecting the positive terminal last and
connecting the positive terminal first? Intuitively, I would want to
the do the exact opposite: disconnect the positive (hot) first, and
connect it last.

 

It is done that way to avoid a possible spark.
Scott

 

=====================================

Because the whole chassis of the vehicle is connected to the NEGATIVE
cable, it's best to remove that wire first. That way you remove 90% of
your chances of shorting the positive to anything while removing it with
your (steel) pliers or wrench. If you did it the other way around, when
you start unbolting the positive terminal you could weld the pliers to
the battery hold-down bracket, the firewall, the fuel filter, brake
lines, hood, etc. The spark can splatter molten metal in your eyes and
start a fire in your clothing or your shop. Such a short can also fry
your computer, apparently. If the short stays shorted more than a few
milliseconds, (a fully charged) battery can explode in a boiling flaming
mess of sulfuric acid.

'Curly'

 

=====================================

Because the whole chassis of the vehicle is connected to the NEGATIVE
cable, it's best to remove that wire first. That way you remove 90% of
your chances of shorting the positive to anything while removing it with
your (steel) pliers or wrench. If you did it the other way around, when
you start unbolting the positive terminal you could weld the pliers to
the battery hold-down bracket, the firewall, the fuel filter, brake
lines, hood, etc. The spark can splatter molten metal in your eyes and
start a fire in your clothing or your shop. Such a short can also fry
your computer, apparently. If the short stays shorted more than a few
milliseconds, (a fully charged) battery can explode in a boiling flaming
mess of sulfuric acid.

'Curly'

 

That helps, didn't know the negative cable was connected to the
chassis.

Let me ask this scenario then: So you've got the new battery seated in
there (nothing connected yet). Now you're connecting the positive clamp
to the positive terminal. Your wrench handle touches the chassis while
the teeth are on positive terminal. Isn't this still going to cause a
short since the chassis is ground?

 

---------------------------

No, because the negative side of the battery isn't connected to anything
yet, so there's no 'path' from positive to negative. Same idea as the
first part of the procedure.

Your owner's manual has an interresting procedure for boosting your
Honda. Similar process and a few extras included. (protecting the
computer).

'Curly'

 

OK, thanks, got it now! I wish manuals would give some explanations for
why certain procedures are followed. It helps to understand the
underlying reason, because it helps you remember the procedure.

It's pretty amazing how many people don't know the real reasons for the
order for jump starting a car (including me, until now). I was reading
some forums, and most people know to attach the negative cable to the
dead car's chassis to avoid sparking an explosion. But most people
didn't think that the rest of the order mattered.