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8 steps on how to replace a car battery box or tray

How to replace car battery box and tray

One of the first items to examine for possible damage when starting any restoration project is the battery hold-down tray. That also includes the area under the tray that is inside the fender well. Years ago, all the hold-down trays were made of metal. After years of being exposed to leaking water or battery acid, many of them have virtually disintegrated.

Disconnection
Remember to put on safety glasses and gloves before working with or around automobile storage batteries. First, disconnect the negative (black) ground cable, then the positive (red) cable. Next, remove the battery hold-down clamps, pull out the battery and set it aside. Be careful not to touch your clothing: If there is any leakage or spillage from the battery, it will eat holes in your clothing. Trust us. For the same reason, it's a good idea to place the battery on wood or rubber (some say that if you leave a battery on a concrete floor it will drain the charge).

Unbolting and removing the old car battery tray can be harder than it looks. The bolts on the tray shown in the above photo were fused with rust, so we knocked them off with an air cutoff wheel. (A cold chisel and a 2-pound hammer will work just as well.)

Cleaning and prep
Using a stiff wire brush or a hobby sandblaster, thoroughly clean the area to get rid of any rust and dirt. Once the area is clean and the bare metal is exposed, you might notice the need to weld some repair patches on the surrounding sheet metal before painting; if not, proceed to wipe down and paint the area with a rust inhibiter. Rubberized undercoating also works very well. The area can then be painted any color desired.

Rather than making the same mistake and using a metal tray as a replacement, it only makes sense to use a hard plastic tray that is very strong, doesn't rust, and is acid-resistant. You can go with a basic tray that comes with the hold-down unit, or a battery-box type originally designed for marine use. The latter has become widely used in race and custom vehicles because it offers more protection and a cleaner appearance.

How-to steps
As you can see from the photos, this is a fairly straightforward project that can be done in an afternoon without too much trouble. The upside is that once complete, other than simple maintenance, the job should never have to be done again.

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Photo 1: After 30-plus years, this is what remained of the original steel battery tray after we removed the old battery.


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Photo 2: With some rust but no serious metal damage, the area under the battery hold-down tray is in pretty good condition.


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Photo 3: Using a stiff wire brush or a hobby sandblaster, clean the area to get rid of all rust and dirt. Once the bare metal is exposed, paint with a rust inhibiter. Rubberized undercoating also works very well. The area can then be painted any color desired.

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Photo 4: A new steel tray brace is painted and bolted on.


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Photo 5: Here are two popular replacement battery trays. Both are made of hard plastic. The one on the right is a basic battery tray that comes with the hold-down unit. The one on the left, originally made for marine use, is a battery box also used in race and custom vehicles because it offers more protection and a cleaner look.


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Photo 6: Position the tray in the fender well and check for fit, then drill the new mounting holes. Use stainless steel nuts and bolts to prevent corrosion. Bolt the battery tray in place.

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Photo 7: Now we are ready to install the battery and attach the hold-down plate. Clean and inspect the battery posts and terminals until they are nice and bright. Next, attach the positive battery cable followed by the negative. Now the job is done.

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Photo 8If you decide to use the marine or racing style battery box, place it over the new battery tray. Drill the corresponding holes and, using the same stainless steel nuts and bolts, attach the battery box and tray to the fender well. Next, refer to the previous photo to finish the battery install. Put the cover over the box and attach the nylon hold-down strap.
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