This is your ultimate guide to deep cycle battery winter storage.

In it, you’ll learn:

The effects of temperature on batteries

Proper deep cycle battery storage practices

Maintaining deep cycle batteries over the winter

And lots more!

Let’s dive in!

How Do Deep Cycle Batteries Work?

Deep cycle batteries rely on an electrochemical process between lead plates and an electrolyte to produce electrical energy.

Let’s expand on this.

Typically, a flooded lead-acid battery consists of:

Lead oxide plate: This is the positive plate and is covered with a paste of lead dioxide

Sponge lead: This is the negative plate

Electrolyte battery fluid: This is a composition of sulfuric acid (usually 30% to 50%) and water

How do these components interact to produce electricity?

Firstly, the two lead plates are immersed in the electrolyte solution.

And electrons are produced when the plates and solution react chemically.

An illustration showing the components of a lead-acid battery
Lead-acid batteries generate electricity from the movement of ions between the plates

These electrons then flow into the device connected to the battery, powering it.

Once the battery is discharged, charging results in the opposite process happening.

That is, electricity from the charger flows into the battery and is converted into chemical energy.

How Does Cold Affect Lead-Acid Batteries?

Now that you know how a lead-acid battery works, it’ll be easier to understand how cold affects them.

Overall, cold weather affects lead-acid batteries in 4 important ways:

The electrolyte can freeze

The battery can lose capacity

The battery will require higher voltages to charge

The battery has a lower self-discharge rate

Let’s go through each aspect in more detail.

1. The Electrolyte Solution Can Freeze

Does battery acid freeze?

Yes, it can.

Here’s how...

When a battery is fully charged, the electrolyte solution (sulfuric acid and water) is evenly mixed.

In that case, the lead-acid battery freezing point is around -76° F.

Hence, a fully charged battery is less likely to freeze in cold temperatures.

However, when a battery is discharged, the sulfuric acid from the electrolyte is embedded in the plates.

And that leaves more water in the battery.

Low temperatures can cause the electrolyte to freeze if the battery isn’t fully charged

Thus, since water has a freezing point of 32° F, the battery is liable to freeze at a relatively higher temperature than when charged.

So, it’s important to keep your batteries fully charged in very cold weather.

That way, you’ll have a properly balanced electrolyte.

And that means the electrolyte will be more resistant to freezing.

What Happens When a Battery Freezes?

The same as what happens when you make ice cubes in a tray.

In both cases, the frozen water expands and pushes against the containment structure.

Frozen electrolyte can cause the battery case to crack

In a lead-acid battery, this action pushes the lead plates together.

And this can cause a short between the positive and negative plates.

As a result, the battery can lose its structural integrity and thus its ability to effectively produce electrical current.

Can AGM Batteries Freeze?

It’s not uncommon to hear the question, “do AGM batteries freeze?”

The answer?

Yes, any AGM battery can freeze in cold weather.

The AGM battery freezing temperature is generally no different from other batteries’ freezing temperatures.

Can Golf Cart Batteries Freeze?

Yes, like all other batteries, golf cart batteries can freeze.

Because batteries can freeze, especially when discharged, the key to protecting any battery from freezing is to keep it fully charged throughout the cold season.

2. You Can Lose Battery Capacity

Besides the potential for freezing, cold weather has a direct impact on battery capacity.

How exactly?

A lead-acid battery’s capacity goes down as the temperature decreases.

And it goes up as the temperature increases.

As the temperature decreases, the battery capacity also decreases

How much?

The rule of thumb for battery capacity is that for every 15° to 20° below 80° F, the battery loses 10% of its capacity.

Thus, you’ll have less available power from a cold battery than one that is at or above room temperature.

3. You Need a Higher Voltage to Charge

If you’re wondering what the effect of temperature on battery voltage is, here’s the deal...

When charging a lead-acid battery at low temperatures, a higher charge voltage is required than at higher temperatures.

Cold temperatures require more voltage to charge the battery

This is because cold temperatures cause the electrolyte to become gel-like.

And that increases resistance in a battery’s chemistry.

As a result, it slows down the electrochemical reaction.

This is why, to improve battery life, charging needs to be “temperature compensated.”

This is especially the case when the battery’s temperature is expected to be below 50° F.

4. The Battery Has a Lower Self-Discharge Rate

Temperature also affects battery charge and discharge rates.

How?

At room temperature (68° F), a lead-acid battery’s self-discharge rate is usually about 3% per month.

Cold temperatures slow down the self-discharge rate of batteries

But, at low temperatures, a battery’s self-discharge is nearly negligible.

The opposite is also true.

At higher ambient temperatures, a battery’s self-discharge increases.

So in effect, a battery loses less of its energy when it’s cold than when it’s hot.

4 Winter Storage Tips for Batteries

This is your “how to store a battery” checklist.

Let’s review our top tips for how to keep batteries fresh during the winter.

1. Choose a Proper Place for Storage

The following factors will guide you on how to store a lead-acid battery:

Where Should Batteries Be Stored?

Storing lead-acid batteries requires some foresight.

The best way to store batteries is to store them in a clean, dry, cool, and frost-free location away from direct sunlight.

A bank of batteries being stored on metal shelving
Store your lead-acid batteries in a clean, dry, and cool plate away from direct sunlight

If batteries are exposed to sunlight, they’ll be exposed to excessive temperature.

If that happens, the battery will stop working, bubble, and bulge.

Also, extreme heat from the sun can cause battery corrosion.

And this can shorten the battery’s life.

Can Batteries Be Stored in the Cold?

Answer: No, it’s not advisable to store batteries in the cold.

As we’ve covered, cold temperatures can cause the battery to lose capacity, can freeze the electrolyte, and can result in your battery not working as well as it should.

But the heart of this question is really: “Do batteries last longer in the cold?”

An illustrated battery shown surrounded by ice and snow
It’s not recommended to store your batteries in the cold. Try to keep the temperature around 59° F

And does freezing batteries extend their life?

The answer to both questions is “No.”

While the self-discharge rate will slow down in the cold, it doesn’t mean the battery will last any longer.

So, what is the proper battery storage temperature?

Try to keep it around 59° F.

Does Concrete Drain Batteries?

The idea that concrete will drain your battery and kill it, and so you should not store your battery on the floor is just a myth.

A battery sitting on a concrete floor
Concrete does not drain your deep cycle batteries any more than other materials

A battery will drain (called “self-discharging”) no matter what surface you store it on.

So, whether it’s stored on wood, metal, or any other surface, the battery will drain.

But concrete won’t make it drain any more or less than other surfaces.

2. Disconnect the Battery

Are you wondering which battery terminal to disconnect for storage?

Answer: The negative (black) terminal.

You should disconnect the negative (black) cable before storing the battery

That way, you can prevent any electrical loads from draining the battery.

This is because batteries experience parasitic “vampire” loads.

These are small power draws that happen even if the appliance being powered is “off.”

And when combined with the fact that the battery self-discharges, this can weaken the battery.

3. Clean the Battery

You should clean the battery prior to storage to remove any corrosion or electrolyte deposits.

That’s because batteries with corrosion, electrolyte deposits, or dirt/dust tend to self-discharge quickly.

A car battery with a corroded positive terminal
Clean your batteries before putting them into storage

Why?

Because they experience transient power loss between the positive and negative terminals.

So, clean the battery terminals with a battery spray cleaner or a baking soda/water mix — as if you’re neutralizing it.

Also, clean the case battery according to your battery manufacturer’s instructions.

4. Charge Fully

Before storing, make sure to charge the battery to a 100% state of charge (SOC) one final time.

Also, ensure that the battery water level is just above the internal plates.

The water level should be slightly above the plate (in orange)

And once stored, periodically check and test the battery’s voltage and specific gravity.

Then, apply a charge when the battery’s SOC falls to 70% or below.

Note: Since lead-acid batteries can have different readings, it’s best to apply the charge based on the manufacturer’s instruction.

Check the manual and confirm because some manufacturers can allow lead-acid batteries to drop up to 60% SOC before recharge.

Now, what are the battery charging guidelines you should follow?

Let’s cover that below.

Use a Winter Battery Charger

The battery charger you use is very important.

You can use a battery maintainer or trickle charger to keep your battery charged while in winter storage.

Battery Maintainers vs. Trickle Chargers: What’s the Difference?

Both of these chargers deliver consistent low-level charges to batteries.

But they aren’t exactly the same.

Here’s the difference:

A trickle charger delivers a charge that is equal to the battery’s self-discharge rate.

Old-style trickle chargers must be disconnected once they’re done charging

Furthermore, this type of charger should be disconnected when it’s done charging.

Otherwise, you risk overcharging the battery.

On the other hand, battery maintainers (also called “float chargers”) are meant to stay plugged in.

Can You Leave a Battery Maintainer on All the Time?

Yes, you can.

The great thing about maintainers is that they’re smart and fully automatic.

So, you can leave them plugged in for a long time.

Battery maintainers are “smart,” meaning they can be left on your battery throughout storage

A battery maintainer’s system is designed to apply the appropriate amount of electric current based on the battery’s charge level.

After the battery is 100% fully charged, the maintainer switches over to float mode.

This way, the maintainer only charges the battery when it drops below a pre-set voltage.

Can You Trickle Charge a Frozen Battery?

No.

Never try to charge, trickle charge, or jumpstart a frozen battery.

Doing so can damage the battery and even cause it to explode!

If you want to use a battery that’s been stored for a long time, first perform a visual check on the case.

When you do this, you’re looking for cracks.

A sealed pair of batteries with distorted cases
Never charge a frozen battery. First allow it to warm. Then check for signs of damage

And if there are cracks, the battery is likely too damaged to continue working.

But if there are no cracks and the battery case looks fine, take it to a warm place to unthaw.

Once the battery is unthawed, see if it holds a charge.

If not, you can try charging it or take it to a battery professional to inspect and test it.

How to Store a Lead-Acid Battery: A Summary

Check the battery for external damage (cracks, leaks, etc.)

Charge the battery to 100%

Disconnect the negative (black) cable

Check the battery’s specific gravity or voltage and ensure they’re correct

Ensure there’s enough fluid (for flooded batteries) and top off if necessary

Clean the battery using a baking soda and water paste

Store the battery in a cool (59° F), dry place where it can’t freeze

To make charging easy, store batteries in an easily accessible location

Confirm that you have the right charger for the battery

In storage, periodically check and test the battery’s voltage

Apply a charge when the battery’s charge falls to 70% or below (or whatever manufacturer’s specification is)

Conclusion

There you have it: Everything you need to know about deep cycle battery winter storage.

Knowing this means you can help extend your battery’s shelf life and reduce safety hazards.

Now, we’d like to turn it to you.

Have you run into problems with frozen batteries?

Do you have any further questions?

Please share with us in the comments section!

Leave a Reply

Your email address will not be published.