Can You Charge a Car Battery Indoors?

Anytime your vehicle’s battery goes dead it will require recharging before you can get back on the road.

Sometimes this can be done safely outside, or even with the battery still in the vehicle. Other times, due to inclement weather or the risk of the charger and battery being stolen you might need to bring the whole operation inside your home for charging.

Can you charge a car battery indoors? Yes, you can. However, working with large energy-dense batteries and energized equipment inside the confines of your own home will necessitate strict adherence to safety precautions to ensure accidents will not occur. But so long as some simple procedures are followed and you use common sense, you won’t have anything to worry about when charging your car battery indoors.

If you have never recharged a car battery inside, you might be a little anxious. Don’t worry, in the remainder of this article we will be sharing with you tips, tricks and proper procedures to make sure the operation is completed smoothly with no mishaps.

Secure the Charging Location

The first thing you need to do before starting your charging operation indoors is secure the area you plan on charging it. Rambunctious kids, and out-of-control pets could spell disaster.

A battery that is knocked over may rupture, spilling corrosive contents on to people and possessions alike. Inquisitive pets might gnaw the cables connecting the battery to the charger, subjecting them to a powerful shock.

You must take the time to prep the area where charging will take place unless every single member of your household, two- and four-legged alike, can be trusted implicitly. Take no chances in this regard!

Do Not Charge Near any Existing Heat Source or Open Flame

Your battery and charger will both get hot during the charging procedure, and the last thing you want to do is conduct this near any other source of intense heat or, even worse, an open flame.

This could result in a dangerous failure condition but more importantly, under certain conditions, explosive gases might be released from your battery while it is charging.

Though it is extremely rare for them to accumulate in any meaningful quantity, it is never out of the question, and especially hazardous should the charger malfunction and begin overcharging the battery.

Keep your charger and battery well away from any installed or portable heater, pilot light, stove, fireplace or oven while charging.

Proper Ventilation is Essential

Properly ventilating the area where charging is taking place is essential for safety and success. Most batteries will emit various gases when they are being charged, and these gases are especially prone to emission in significant concentrations when rapidly charging a battery or overcharging it.

The emitted gases include hydrogen, hydrogen sulfide and oxygen. The first two can be particularly troublesome, even dangerous, if allowed to accumulate in significant concentrations.

To prevent injury and a potential explosive atmosphere hazard, the charging area must be ventilated, ideally with both an influx of fresh air and an open window that can vent gases to the outside.

If this is not possible keeping multiple floor fans running, or a whole-house attic fan running, should be sufficient to, at least, disperse accumulating gases.

The first gas, hydrogen, is well known for being far lighter than air and even helium, and is extremely energetic and explosive once it has accumulated in quantity. It is odorless and tasteless.

However, its extreme mobility in air means it is very unlikely to accumulate in anything but the most tightly sealed room. It will escape through the smallest cracks and confines to exit a structure.

However, it must not be treated lightly, because even a minor concentration that does build-up could render the local atmosphere explosive.

Hydrogen sulfide gas is altogether different though it does feature hydrogen as a component. This gas is detectable via its rotten, noxious odor and it is significantly heavier than air meaning it will sink and accumulate near the floor.

This presents a legitimate hazard to pets and children, and also makes it more likely to build up in significant quantity. Hydrogen sulfide gas is corrosive, it can irritate mucous membranes and airways, and can discolor household materials and furnishings.

In order to prevent any gases emitted while charging from becoming hazardous in any fashion make sure ventilation is continuous and assured while charging your battery indoors.

Preventing Contact of Battery Terminals

Once the battery is charged, and especially while it is being charged, you must take all necessary precautions to prevent any conductive object from bridging the gap between the terminals, or the charger’s leads affixed to the terminals.

If this occurs the battery will short-circuit and the contacting item will become extremely hot to the touch.

This might melt the item or cause it to burst into flames, and could potentially even contact-weld the item in question to the terminals. This will cause a runaway heating cycle which will result in the terminals and the item melting into the casing of the battery.

When the now red-hot object reaches the chemicals inside the battery’s casing, they will be flash boiled and potentially explode, showering the surrounding area with extremely hot corrosive material.

Needless to say, this is the last thing you want to happen inside your home! Ensure that the immediate area around the charging operation is kept entirely clear of any and all objects which could be pushed, knocked or made to fall onto the battery or the charger during operation.

Once again, this is a primary reason why pets and children must be kept out of the charging area and the charging area secured against intrusion or interference.

Don’t Leave Charger and Battery Completely Unattended

If your charger malfunctions or if it has incorrect settings due to human error the battery might begin to overcharge. This can potentially be detected and arrested if you are in the area and paying attention.

If you are out of the house, outside or asleep you might be facing the aforementioned dangerous build up of gases, or even a potential fire due to your inattention. Don’t risk it!

You should initiate your charging operation when you know you will have the most time to be near the charger and the battery. Don’t set it up right before you go to bed, and then go to sleep trusting that nothing bad will happen.

If you absolutely must leave the battery on the charger unattended and cannot afford the time to turn it off and resume charging later you must triple check all connections, all charger settings and the overall condition and health of the battery before leaving.

Also never, ever leave a battery charging while you are away from it unless the charger has a dedicated “maintenance” or “float” setting that will shut the charger off once the battery has reached full and nominal capacity.

Conclusion

So yes, you may safely charge a car battery indoors as long as you are careful and institute proper safety procedures. Ventilation is a must as is keeping kids and pets out of the charging area.

You should never leave your battery and charger unattended while charging operation is underway, nor should you ever charge the battery near a source of heat or open flame.

By following these simple rules and using a little common sense you may charge your car battery inside, safe and sound.