Replacing the battery in our C7s:
This is a relatively easy job, especially once you first know what needs to be done. It will take you about 30 or so minutes. The only tools you will need are a flat heat screw driver, 10 mm and 13 mm sockets, and some means of lifting out the original battery once disconnected. It does not have any built-in handles, so you will need either a cheap lifting strap that temporally attaches to the terminals, or the hardier sliding clamp or ‘ice block’ lifting claws. Our cars do not need to have auxiliary power supplied while you disconnect the battery. In most cases you will find that once you connect the new battery, your car alarm might go off, and you just need to press the unlock on the FOB. Then it might take a couple of cycles (on, off) for all electronics to return to their normal settings.
There are several options available in addition to the OEM battery. I prefer to go with AGM batteries when I replace the originals in my cars. Sears carries a number of size 48 AGMs that will work, but the one I went with was from Batteries Plus, a X2 Power AGM part number SLI48AGMDP. It has a 5-year 100% replacement warranty, and 775 CCA. Here is what it looks like. [Note: if you click on an image here, it will enlarge to make viewing it easier]

And it is made in the USA just like our C7s

I suggest you protect your C7 from inadvertently scratching it by putting a protective cover over the trunk edge and right rear fender.
The first thing you will want to do, is to use your hand and gently pry the right-side plastic wheel well interior cover away just enough that you can comfortably slip the floor carpeting out from under it. As you can see in this photo,

there are 3 attachment clips that release when you pull the cover. It is important to do this so that you don’t end up ripping the carpeting where it goes under the cover. Just ease the carpeting back enough so that you have clear access to the foam hatch on top of the battery, as you can see in this image. Then just place something heavy on the folded back carpeting to keep it out of your way.
This is what you will see above the battery compartment, when you the carpeting back.

This is what you will see once you lift the foam cover:

In this image, you see the 5 sets of nuts that you will be loosening and or removing.

The first one is labeled 1 and is the negative ground cable. Note that it has a small additional wire attached to it (marked with a yellow arrow and caution triangle). You will loosen the 10-mm nut on the post clamp, which should allow you to slide the negative wire unit including the small wire, up off of the post. Once you do this carefully tuck the ground wire unit with the small wire out of the way.
As you can see here, I tucked it between the plastic wheel housing cover and the carpeting.

Next you want to undo the positive heavy-duty line that goes up to the engine. This is number 2 in the picture. Tuck that away (down between the battery and rear wall will work). Next you will be removing the nut that secures the fuse block. That is number 3. Loosen it the same way you did the negative post clamp. Now to get the fuse block to release, refer to the two green arrows in the picture at the top and bottom edge of the fuse block. Insert you flat head screw driver down into one of the slots while gently lifting the fuse block up. You should feel the catch release. Do the same on the other one and then lift the fuse block up and place it to the left of the area, out of the way. Finally, use your 13mm socket and unscrew the battery hold-down brace. These nuts are labelled 4 in the picture.
Now you should have everything disconnected from the original battery except the gas venting tube that is between the negative side and the outer wall (left of the arrow in this picture).

Just detach the tube from the elbow connector. Use your battery remover strap or clamp to lift it up and out. Be careful not to bump or hit your C7 body with it as you move it clear of your car.
Next, remove the vent hole cap from the OEM battery side (it is on the positive post side) and the vent hole elbow connector (on the negative post side) and place them in your replacement battery in the same positions.
Now you are ready to ease your new battery into the trunk floor. Remember the positive post goes to your left (with you standing facing the trunk) and the negative post on the right side.
You now reverse the steps you did above. You reattach the gas vent tube to the elbow. Put the battery hold down brace back and tighten down the nuts. (I realized I forgot to put the bracket back until I had secured the positive line to the engine, so I had to take that back off to get the bracket in properly
). Next slip the fuse block assembly back over the positive terminal and push down at the top and bottom until you hear the clips ‘click.’ Then tighten the positive terminal connection (#3) down. Follow by connecting the positive line to the engine (#2), and finally the negative post assembly (with the small negative line) #1.
You should now have everything connected (your trunk light will come on when you do, and if your C7 is set to auto lock, most probably the alarm will also go off. If it does, just unlock with you FOB unlock button).
Once you are satisfied that all nuts are properly secured, replace the foam battery cover. Then gently slip the carpeting back under the plastic wheel well cover. Next, give the plastic cover a gentle thump with your hand at each of the 3 attachment clip areas. If you have them aligned, it should easily push home.
When you first start you C7 you may notice a few things are not quite right- the HUD (if you have one) may revert to its default, the outside temperature display may be --, as well as the tire pressure readings may also be --. I drove RedHot for a nice freeway drive and then shut it down. When I restarted her, the outside temperature read correctly as did my tire pressure readings. I also reset HUD to my preferred display.
I anticipate there are other ways to do this replacement. My intent in writing this up was to share with you the way I did. If it helps you when you decide to change yours, all the better.
This is a relatively easy job, especially once you first know what needs to be done. It will take you about 30 or so minutes. The only tools you will need are a flat heat screw driver, 10 mm and 13 mm sockets, and some means of lifting out the original battery once disconnected. It does not have any built-in handles, so you will need either a cheap lifting strap that temporally attaches to the terminals, or the hardier sliding clamp or ‘ice block’ lifting claws. Our cars do not need to have auxiliary power supplied while you disconnect the battery. In most cases you will find that once you connect the new battery, your car alarm might go off, and you just need to press the unlock on the FOB. Then it might take a couple of cycles (on, off) for all electronics to return to their normal settings.
There are several options available in addition to the OEM battery. I prefer to go with AGM batteries when I replace the originals in my cars. Sears carries a number of size 48 AGMs that will work, but the one I went with was from Batteries Plus, a X2 Power AGM part number SLI48AGMDP. It has a 5-year 100% replacement warranty, and 775 CCA. Here is what it looks like. [Note: if you click on an image here, it will enlarge to make viewing it easier]
And it is made in the USA just like our C7s
I suggest you protect your C7 from inadvertently scratching it by putting a protective cover over the trunk edge and right rear fender.
The first thing you will want to do, is to use your hand and gently pry the right-side plastic wheel well interior cover away just enough that you can comfortably slip the floor carpeting out from under it. As you can see in this photo,
there are 3 attachment clips that release when you pull the cover. It is important to do this so that you don’t end up ripping the carpeting where it goes under the cover. Just ease the carpeting back enough so that you have clear access to the foam hatch on top of the battery, as you can see in this image. Then just place something heavy on the folded back carpeting to keep it out of your way.
This is what you will see above the battery compartment, when you the carpeting back.
This is what you will see once you lift the foam cover:
In this image, you see the 5 sets of nuts that you will be loosening and or removing.
The first one is labeled 1 and is the negative ground cable. Note that it has a small additional wire attached to it (marked with a yellow arrow and caution triangle). You will loosen the 10-mm nut on the post clamp, which should allow you to slide the negative wire unit including the small wire, up off of the post. Once you do this carefully tuck the ground wire unit with the small wire out of the way.
As you can see here, I tucked it between the plastic wheel housing cover and the carpeting.
Next you want to undo the positive heavy-duty line that goes up to the engine. This is number 2 in the picture. Tuck that away (down between the battery and rear wall will work). Next you will be removing the nut that secures the fuse block. That is number 3. Loosen it the same way you did the negative post clamp. Now to get the fuse block to release, refer to the two green arrows in the picture at the top and bottom edge of the fuse block. Insert you flat head screw driver down into one of the slots while gently lifting the fuse block up. You should feel the catch release. Do the same on the other one and then lift the fuse block up and place it to the left of the area, out of the way. Finally, use your 13mm socket and unscrew the battery hold-down brace. These nuts are labelled 4 in the picture.
Now you should have everything disconnected from the original battery except the gas venting tube that is between the negative side and the outer wall (left of the arrow in this picture).
Just detach the tube from the elbow connector. Use your battery remover strap or clamp to lift it up and out. Be careful not to bump or hit your C7 body with it as you move it clear of your car.
Next, remove the vent hole cap from the OEM battery side (it is on the positive post side) and the vent hole elbow connector (on the negative post side) and place them in your replacement battery in the same positions.
Now you are ready to ease your new battery into the trunk floor. Remember the positive post goes to your left (with you standing facing the trunk) and the negative post on the right side.
You now reverse the steps you did above. You reattach the gas vent tube to the elbow. Put the battery hold down brace back and tighten down the nuts. (I realized I forgot to put the bracket back until I had secured the positive line to the engine, so I had to take that back off to get the bracket in properly

You should now have everything connected (your trunk light will come on when you do, and if your C7 is set to auto lock, most probably the alarm will also go off. If it does, just unlock with you FOB unlock button).
Once you are satisfied that all nuts are properly secured, replace the foam battery cover. Then gently slip the carpeting back under the plastic wheel well cover. Next, give the plastic cover a gentle thump with your hand at each of the 3 attachment clip areas. If you have them aligned, it should easily push home.
When you first start you C7 you may notice a few things are not quite right- the HUD (if you have one) may revert to its default, the outside temperature display may be --, as well as the tire pressure readings may also be --. I drove RedHot for a nice freeway drive and then shut it down. When I restarted her, the outside temperature read correctly as did my tire pressure readings. I also reset HUD to my preferred display.
I anticipate there are other ways to do this replacement. My intent in writing this up was to share with you the way I did. If it helps you when you decide to change yours, all the better.
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