Can a Car Battery Get Wet? [Is It Even Safe!]

Car batteries sometimes get wet or even submerged in water and the question most car owners have is whether batteries can still safely be used after they have become wet.

Generally speaking, car batteries can get wet but are in most cases not damaged by water. The batteries are designed to keep moisture out and therefore it is safe to use a wet battery. Even batteries that have been submerged in water will normally not be damaged easily.

In this article, we’ll look at the most frequent questions asked by car owners regarding car batteries that have become wet or are kept in a humid environment. 

1. Can a Car Battery Get Wet?

Most modern car batteries are designed to withstand moisture and even water. Batteries are usually packed in a manner that neither the water from outside can not penetrate the outer container nor do the internal components leak outside the battery!

A car battery is designed to stay free of moisture on the inside. To achieve this, modern car batteries cases are made of polypropylene resin. This is the ideal material to keep water and moisture out. 

Thus, when your car’s battery is getting wet you don’t have to worry too much.

However, there are certain wet conditions you should try to avoid. For instance, if you leave your car battery out in the rain for days, chances are that the terminals and lid, which usually come in direct contact with the outer environmental elements, can get damaged.

We’ll discuss these factors in detail later in this article.

Thus, even though a car battery can get wet and withstand water, it is better to not get the batteries wet unnecessarily. If you don’t plan to use your car for a long period of time, it is better to put the car batteries in a safe place where they cannot easily get wet.

2. Does Rain Affect Your Car Battery?

Photo by Kaique Rocha from Pexels

Rain normally doesn’t directly affect a car battery negatively or positively. And if the battery is not getting wet as a result of the rain, the rain will not affect the working of your car battery at all. 

Rain and Cold Weather 

But rain and cold temperatures often go hand in hand during wet and cold months. And what you might consider as negative effects the rain has on your car’s battery, is in most instances a result of the cold conditions and not the rain. 

Cold temperatures can slow down the chemical reactions in the battery. Cold also affects the gravity of the electrolyte contained in the battery case.

If you witness extreme cold temperatures in your location, chances are that your car batteries can even freeze! If so, make sure you click on the link to check out my other article where I provide a full guide on whether car batteries can freeze, and what to do when that happens!

That said, rain and the accompanying humidity levels as such don’t affect the function of the battery. Humidity also doesn’t damage any internal components of the battery. 

Why Does Your Car Battery Become Weak During the Rains?

You may now wonder why you may sometimes experience as if your car’s battery is becoming weaker when it rains.

Your car batteries may seem to drain faster and become weak during the rainy season. This is not due to a possible wet battery but because you may be forced to drive slowly due to traffic or drive your car less frequently. As a result, your battery won’t get enough time to charge itself sufficiently.

When you encounter a rainstorm when driving, you can be caught up in heavy traffic that has slowed down to a crawl. When driving slowly, the engine and alternator are not providing the revolutions needed for a full charging function and the battery can lose power. 

When you then simultaneously are using your windshield wipers, having your lights switched on, using the back window demister, and is probably using the car’s air conditioning  – all things that tap electricity from the battery – the battery can get weaker.

A car battery’s reserves are tapped heavily at low speeds. To replenish power to the battery you’ll have to drive at a “normal” speed for a while as soon as possible. 

Furthermore, if it rains heavily for a few days, chances are that you may choose not to take out your car. As a result, your car can end up sitting for days and chances are that your car battery may die from your car sitting for too long!

I’ve actually written a detailed article on whether a car battery can die from your car being unused! In it, I’ve also provided tips on what to do if you have no choice but to leave your car stationary for many days! Make sure to check it out so that you don’t face such issues.

To summarize: Rain can affect your car battery’s performance indirectly because you’re tapping a lot of energy from your battery and not charging it fully.

3. What Happens If Your Car Battery Gets Wet? Does It Stop Working?

In most cases, a car battery will continue to work even if it gets wet. The car battery is sealed (usually using polypropylene resin or similar material) in a manner that rainwater or even moisture doesn’t penetrate its outer body; thereby ensuring that the battery continues to function.

It may sound strange, but nothing happens to your car battery if it gets wet. In other words, the battery keeps on functioning normally and does not stop working. 

The reason for this is that a battery is designed and built in such a way that it keeps water out. The polypropylene resin battery case and the effective sealant keeps water and moisture outside the battery.

And without entering the inner side of the battery the water cannot have any influence on the electrolyte or the chemical reactions inside the battery. So, it can’t stop the battery from working. 

The terminals of a modern car battery are also made from material that is corrosion resistant and doesn’t rust easily. 

4. What Happens to the Car Battery If It Gets Submerged in Water?

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I’m confident that you wouldn’t deliberately submerge your car or a car battery in water. It may, however, be submerged accidentally. It might be that your car has to go through a puddle that is deeper than you thought!

The question arises whether the battery will continue to work once your car emerges out of the water.  

A car battery is designed to withstand water, even when submerged in water. Apart from the battery case that is made of polypropylene resin that will keep water out, the sealant on a battery is specifically designed to keep water and moisture out – even if it is submerged into water. 

Thus, when a car battery is submerged in water for a short period it should not be a problem. The battery case and the sealant will do their job and keep the water out.

If your car was for whatever reason submerged in water for a short period or you had to drive through a submerged area and the battery become submerged as well, the battery should not suffer any damage and keep on working.  

However, if the battery is left submerged for a long period, the metal parts of the battery might eventually rust and corrode where it touches the water. Then the chemicals inside the battery can leak out through these rust holes in the battery casing. This will render the battery useless.

5. Car Battery Left Out in Rain? Is It Safe to Use?

When you leave a car battery out in rain, the humidity levels during the heavy rains may lead to corrosion forming at the battery connections. 

If there is water between the terminals there will be some current flow through the water but it will not cause a short circuit. The current flow will be minimal and completely harmless to you. 

So, the humidity levels during rainstorms can contribute to corrosion forming at the battery connections, but it rarely affects the function of the battery’s internal components. 

6. Can You Start a Car With a Wet Car Battery?

The cold and moisture combination might also lead to corroded connections and the car battery may become sluggish and struggle to provide enough charge to start your car. But in normal circumstances, a wet battery should not prevent the car from starting. 

You can even use a wet battery to jump-start another car. The moisture will have little to no negative effect. 

7. Can You Jump Start a Wet Car Battery?

Experts say jump-starting a car in the rain is safe because the voltage of a vehicle is not high enough. The water will not be a problem as long as you follow the same sequence as if the battery is dry.

Jump-starting a car in the rain is considered no more dangerous than doing it on a sunny, dry day. 

The Basic Sequence to Follow

  1. Turn both cars off before connecting the cables.
  2. Put one of the cables’ red clamps on the positive terminal of the weak/dead and wet battery and put the other red clamp on the positive terminal of the good battery.
  3. After you’ve put the black clamp on the negative terminal of the good battery, ground it to a large metallic part of the engine block of the car with the dead and wet battery. 
  4. Start the car with the good battery and then the one with the bad battery.  
  5. While the engines are running, disconnect the cables in the reverse order.
  6. Drive the car with the wet battery (or leave it idling) for at least 30 minutes enabling the alternator to recharge the battery.

Thus, it is generally quite safe to jump-start your car in the rain or when the battery is wet.  The metal leads you use to connect to the terminals are safe whether it is a rainy or sunny day. 

8. Can You Charge a Car Battery in the Rain?

Although it is not a problem for a battery to be charged when it is wet, it is always good practice not to charge your car battery outside in the rain.

The reason is that the charger can get wet and as chargers often work with high voltage it can be dangerous for the charger to get wet. So, it is a good rule not to charge a car battery in the rain unless the charger is protected against wet conditions.

That said, if you want to charge the car using the car alternator, you can definitely do so without any issue!

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