How do you change a battery?

[NorrisB]

What Im confused about is the order of removing and than reconnecting the battery.

First of all does order even matter?

i think the order is like:

old battery
1. Remove positive first
2. remove negative

inserting new battery
1. insert positive first
2. insert negative

I'm an electrical engineer in my labs delt with 10-15v power supplies and never ever did we worry about the order in which we hook up or disconnect a power supply why does it matter with cars? If either terminal is disconnected its an open circuit with no current going through the car how could it possible be dangerous?

 

[supton]

It doesn't.

However, most recommend the neg first. If you mess up, and touch the wrench to the fender while wrenching on the neg terminal, nothing will happen. Not so if you do the pos first.

It matters not for the electronics in the car as much as not blowing up the battery in your face. If you a re careful--which you should be regardless--then you can do pos first. I've done pos first a number of times.

These days you might not even need to rdo the presets in the radio.

 

[heynow]

I believe many people remove the negative first, and add it second, so that if the tool (wrench/ratchet) you are using to tighten the terminal clamp accidentally comes into contact with a metal parts of the body while tightening, it will not short out the battery.

 

[beast3300]

I don't know if it does matter but I remove the negative first and reinstall it last.

 

[NorrisB]

Originally Posted By: beast3300
I don't know if it does matter but I remove the negative first and reinstall it last.


so it should be like
old battery
1. Remove negative first
2. remove positive

inserting new battery
1. insert positive first
2. insert negative

 

[beast3300]

Originally Posted By: NorrisB
Originally Posted By: beast3300
I don't know if it does matter but I remove the negative first and reinstall it last.


so it should be like
old battery
1. Remove negative first
2. remove positive

inserting new battery
1. insert positive first
2. insert negative


Yes sir

 

[NorrisB]

Thanks guys. that clears things up

 

[yonyon]

What supton said.

You can also hook up external power before disconnecting the battery so you don't have to worry about issues such as the computer forgetting how to idle or the radio forgetting it isn't stolen. An itsy-bitsy battery jumped into the system won't make big scary sparks and will keep memory alive unless you short it out.

 

[sciphi]

What others have said, always remove the negative first.

 

[Quest]

Always remove the -ve 1st, then positive (installation is the reverse, meaning +ve 1st, the negative last).

Why? Almost all modern automobile are -ve ground/chassis, meaning that if you touch on the +ve first during remove, the likeliness of your tool hitting something -ve is very, very high...and when spark flies, anything could happen afterwards.

Removing -ve 1st is the only way to go...same applies to jumper cables.

Q.

 

[HTSS_TR]

Originally Posted By: yonyon
What supton said.

You can also hook up external power before disconnecting the battery so you don't have to worry about issues such as the computer forgetting how to idle or the radio forgetting it isn't stolen. An itsy-bitsy battery jumped into the system won't make big scary sparks and will keep memory alive unless you short it out.

+1

 

[lockguy]

when hooking up the new battery, Im pretty sure you want to hook up the negative back up first since its "grounded" to the frame. I am a locksmith who also does jumpstarts on occasion. Even my jumppack I use it says to hook up the neg side first and disconnect pos first.

 

[The_Jeff]

Originally Posted By: yonyon
What supton said.

You can also hook up external power before disconnecting the battery so you don't have to worry about issues such as the computer forgetting how to idle or the radio forgetting it isn't stolen. An itsy-bitsy battery jumped into the system won't make big scary sparks and will keep memory alive unless you short it out.


If you do this you still have to be careful with the positive cable. Otherwise you'll blow the fuse for whatever your backfeeding-- typically the OBDII connector or cigar lighter.

I have a backfeeder and think it has a 15 amp fuse. If I were really paranoid I could replace this with a 3 amp so I'd blow it first. Instead I've been lucky, and also I wrap the + cable with a rag before draping it inside the engine compartment. Usually there's a non-conductive air intake or upper radiator hose I can jam it in.

 

[yonyon]

Yes, but you won't be throwing an arc that welds your wrench to anything or starts a fire so there really isn't much of a downside.

 

[Kestas]

A long time ago I loaned my tools to a guy who lived a few apartments over so he could change his battery. When I peeked through the window, I could see lots of sparks flying from under the hood.

 

[Mr_Incredible]

It doesn't matter so much which post you unhook first as it does that your cables not touch anything metal. At least, that's how I see it.

The most important thing is to ensure you are wearing eye protection and know how to get to the water hose in case things go horribly wrong. I used to inspect the eye/body wash station in our UPS rooms regularly, and ensure they worked as advertised. Acid has not been very,very good to me over the years.

 

[TechnoLoGs]

I always, always disconnect the negative terminal first, this way the current has nothing to come back to. I also reconnect in the opposite way, or put the negative cable back on last.. this way, grounding the circuit.

 

[Astro14]

Originally Posted By: NorrisB
What Im confused about is the order of removing and than reconnecting the battery.

First of all does order even matter?

i think the order is like:

old battery
1. Remove positive first
2. remove negative

inserting new battery
1. insert positive first
2. insert negative

I'm an electrical engineer in my labs delt with 10-15v power supplies and never ever did we worry about the order in which we hook up or disconnect a power supply why does it matter with cars? If either terminal is disconnected its an open circuit with no current going through the car how could it possible be dangerous?


You've got the order wrong (and I see now that others have correctly ID'd the order as well as the reason).

To remove: neg 1st, then pos.
To install: pos 1st, then neg.

There are two things that happen in a car that don't in your lab:

1. you could ground your wrench against the frame/body. IF you do the negative first on removal, then no worries...do the positive first on removal, you close the circuit...with often spectacular results. The reverse is true on re-installation.

2. the car's computers reboot after electrical power is reapplied, so, in some cars (my P2 Volvos in particular), the battery has to be reconnected with the key in the accessory position so that the boot sequence happens properly. Otherwise, the CAN doesn't boot up in sequence and the climate control, sunroof and other components may not operate correctly.

But reason 1. is critical - so you don't fry yourself or your battery.

 

[Vikas]

Originally Posted By: Astro14

2. the car's computers reboot after electrical power is reapplied, so, in some cars (my P2 Volvos in particular), the battery has to be reconnected with the key in the accessory position so that the boot sequence happens properly. Otherwise, the CAN doesn't boot up in sequence and the climate control, sunroof and other components may not operate correctly.

Never knew that! Are there more cars with that kind of requirement? One would think that engineers would have the firmware designed to allow the most common case aka battery replacement and handle the boot sequence with appropriate delay period. I mean even my home cable and external wireless router and PC etc usually handle power outage and come back properly even though it is recommended to follow the power cycle order if you are doing it by hand.

It is maddening to observe the stupidity when you know how easily it could have been avoided. Don't these guys ever use the stuff that they design???? This is a curse of being engineer. You always *think* that you could have done their job better

 

[Astro14]

It's odd, I will admit, but true...and in the OM...

In fact, when my wife's XC had climate control issues, I disconnected the battery and reconnected as above. Modules rebooted and the climate control was back to normal..,