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Purpose of round holes in the bottom of the battery well?
The battery box in my MY81 has 4 round holes in the floor of the battery well (5 actually if I count the rusted out section in the rear of this well). I am curious as to their purpose....drainage?....ventilation?....make neophyte owners such as myself scratch my head?
I put an AGM battery in my car and my battery compartment is no longer air tight on the top because of the additional corner I've removed to run the stereo and additional electronics I have in my car, so I sealed all those holes to keep the battery compartment clean and dry. Used rubber grommets on the factory holes and then where the battery hold down kit bolts come through, used lock nuts with fender washers & neoprene washers on both sides to make the seal. It's not pretty from underneath, but it's nice and dry in there now. The battery can't move at all and the compartment lid is lined with thick rubber so no chance for a short. My car has a trunk that's also not air tight and I created a firewall to separate the trunk from the interior so no concerns about vented battery gasses in the interior for me.
These pictures are helpful...thank you! It appears that the 2 smaller factory holes that you've plugged with rubber grommets were designed to vent battery gases and the larger ones are for a battery hold down kit which I do not have. Instead, I've pressed some rigid foam Styrofoam between the battery and the sides of the well which prevents any movement. I will leave the holes as they are except perhaps for the "aftermarket" rusted out hole in the back of the well.
The factory hold-down actually holds the battery down as much as it keeps the battery located in the box. The terminals have a habit of shorting against the metal lid when the battery bounces. For regular wet lead-acid batteries, the hard short circuit risks the battery exploding in the box. The holes in the bottom may be momentary blow-out vents, plus the fluid has a place to drain. Do yourself the favor of finding or making a proper hold-down. The problem is particularly acute when the wrong sized battery is fitted. The original Group 49 battery has recessed posts with protective plastic covers that fit over the terminal areas. Make sure those and the vent hose(s) are correctly fitted too. For some AGM and spiral-wrapped AGM batteries, the posts stand above the top of the casing, making the issue even more acute.
Use Good Sense as you proceed. A plastic marine battery box may be a good drop-in protection option too, with the full cover.
More excellent advice...thank you! I do have a secure protective plastic cover over the + terminal but the - terminal is exposed. As a first step, I will cover the underside of the lid with rubber as Petza914 has done.
01-31-2021, 03:06 PM
Purpose of round holes in the bottom of the battery well?
