A lot of people purchase boats without knowing how to take care of them thoroughly. Some boat owners (mostly new buyers) don’t understand that with a boat, comes a lot of maintenance. This could be overwhelming for some, and it is easy to forget the simple stuff like the battery.
Batteries can be expensive and tricky to replace. It is only beneficial that you learn to maintain and care for it properly. You wouldn’t want to have to buy a new battery just because you didn’t know how to inspect and maintain it.
I have done a lot of research on this topic and hopefully will be able to answer most of the questions you have and don’t have about your boat’s battery. I’ll go ahead and answer your first question.
So, can a boat battery freeze and still work? Unfortunately, only an AGM (Absorbed Glass Mat) battery can still function properly after freezing. The most common marine battery, which is the flooded battery, will be damaged once frozen. And, although a gel battery can withstand freezing temperatures, once it’s frozen, it most likely won’t start up again after letting it thaw out.
If you are trying to charge your battery after it froze make sure you let it thaw before doing so. Make sure you allow the battery to thaw somewhere vacant like your garage or shed. Do not thaw out your battery inside your home; you risk leakage, and possibly an explosion when hooking up the battery to charge.
We’ll cover more about how to check a frozen battery in this post, but first let’s talk about the three different marine batteries, and how they handle being frozen.
Three Types of Marine Batteries
- Flooded Lead Acid (FLA)
- Gelled Electrolyte (Gel)
- Absorbed Glass Mat (AGM)
How to tell which battery you have?
Each battery is labelled to let you know which type you have. The batteries will be labelled by both name and manufacturer number. You can figure out which battery you have by either one. Usually, the simpler way to identify the battery is by the label name, which isn’t always the same on every battery of the same type.
List of label names for the flooded battery:
- Liquid lead-acid
- Lead-acid
- Flooded lead-acid
- Wet acid
List of label names for gel battery:
- Gel-Filled
- Gel type
List of label names for AGM battery:
- Absorbed Glass Mat
- Valve regulated
- Sealed regulated valve
- Non-spillable
- AGM
- Dry cell
A flooded battery is the easiest to indicate just by looking at it. It will have tops or caps that are removable for refilling with water. Also, if you give the battery a little shake, you will be able to hear the liquid inside swish around. You definitely will not hear fluid moving around with AGM or gel batteries.
AGM and Gel batteries don’t differ much when it comes to appearance, but if you’re uncertain about which one you own, check the label for one of the names I provided above. You can always check the manufacturer number to look up the details about your battery.
How each battery reacts after freezing?
A flooded battery would be the most vulnerable when frozen, especially if it were completely discharged. There is a chance that your battery won’t freeze if it’s completely charged. But, once a flooded battery is frozen, and shows clear signs of damage, the battery has no chance of surviving.
An AGM battery, on the contrary, is durable and is made to endure harsh conditions. This battery is designed to last long, that’s why it’s clearly the most expensive. An AGM battery won’t freeze as easily as the flooded. It’ll take some pretty cold weather to get this battery to freeze.
If by chance, it does freeze, the battery will still work once you fully charge it.
With a Gel battery, you have almost the same durability as the AGM; it won’t easily freeze, but once frozen, the battery becomes lifeless just like the flooded battery.
It’s always best to keep your batteries fully charged when stored in your bilge (battery compartment of the boat).
Completely disconnect the battery and store it somewhere warm over the winter when you won’t be going on boating trips.
Signs That Your Battery is Frozen
There are some physical signs to tell if your battery is, in fact, frozen that can be easily recognized.
Is your battery cracked? Make sure to check the entire battery carefully for cracks. Feel around it, they could be minimal and hard to see. Look for swelling of the battery. This shouldn’t be hard to spot. Usually, your battery will look distorted if there is swelling.
This other sign is only for flooded batteries. Shake the battery, and if you don’t hear any water moving around, then it’s definitely frozen.
Once you’ve acknowledged that your battery is indeed frozen, you can do some things to check if it’ll still work or not.
How to charge your battery once it’s been thawed?
There might be a slim chance that your flooded or gel battery survived the freeze. Although this is unlikely, if you don’t want to throw out the battery until you’re sure it doesn’t work, I will explain to you a safe way to check your battery’s power.
Take the frozen battery and place it somewhere out of the cold; garage or shed will do. You don’t want to let a frozen battery thaw in your home, you could risk the acid leaking out of it.
Once the battery has thawed, you don’t want to be near it when hooking it up to the charger. I suggest putting the battery outside and plugging it into the charger without the charger being plugged into the wall. Attach the charger to an extension cord, then plug the extension cord into an outlet away from the battery.
To check the battery, you’ll need a voltmeter. Attach the voltmeter to the battery when you’ve hooked up the charger and extension cord. If your battery is charging, the voltage will be accelerating.
If your battery does charge, make sure you check the voltage to make sure it’s not dropping so quickly. If the voltage does drop in a short amount of time, then your battery is damaged and done for.
Battery Storage
The best way to keep your battery from freezing is knowing how and when to store your battery. You’re most likely not going to use your boat over the winter, so I’d recommend removing the battery from the boat to save it from freezing.
Place the battery anywhere that isn’t going to get below freezing. It helps to put it on a shelf rather than the cold ground, even though people have found this to be a myth, I would still consider not putting my battery on the cold, hard ground.
Keeping the battery in storage will also allow you to charge it when needed so that once you’re ready to go out on your boat again, your battery will be fully charged.
How Long Will a Marine Battery Last?
There are a few things that would determine this answer, and there is no exact answer.
Your boat battery will probably last between 2-6 years. It all depends on how you maintain the battery and how much power you’re using on your boat.
There’s always the question: how long should my boat battery last? Again, it all depends on how much you use your boat. I wouldn’t go changing a perfectly fine battery just because you’ve had it for over 5 years.
If your battery is over 5 years old and still running fine, there’s no need to replace. Once you start seeing signs of failure, then is the time to get you a new battery.
How to Take Care of My Boat Battery?
How to maintain your battery so it will last longer. There are many ways you can care for your battery to get the most out of it. These tips are mostly for flooded batteries, but it’s always good to check on your gel and AGM batteries as well.
- Always wipe the top of your battery to keep it dry and clean. Dirt and acid can accumulate on the cap over time which will make your battery drain.
- Clean off the corrosion that has built up around the clamps. You can apply petroleum jelly around them to stop the corrosion from building up.
- If you have a battery that’s mostly in storage, make sure always to keep it fully charged.
- Always make sure you have enough water in the battery. Refill it with purified water. It won’t hurt the battery to fill it with tap water now and then, but don’t make it a habit. Tap water can certainly shorten the life of your battery due to all the minerals.
Keep these tips in mind when caring for your boat’s battery, and it will definitely last you a good amount of time!