If you’re going to leave your batteries in storage for a lengthy amount of time, you should know about trickle chargers. They’re designed for just that: trickle charging your batteries. And they can be a game-changer when it comes to battery storage. But what exactly does a trickle charger do? And how long should you leave your batteries plugged into one? 

Below we take a deep dive into the science behind trickle chargers and why you might want to consider purchasing one for your batteries. Let’s begin. 

What Is a Trickle Charger? 

A trickle charger is a device you can hook up to your batteries to maintain their charge. Because all batteries experience some degree of self-discharge (even when they’re not hooked up to any electronics), it’s important to keep them hooked up to a power source when they’re stored for long periods of time. Otherwise, you might just come back to dead batteries. 

Luckily, trickle chargers are relatively simple and easy-to-use devices. They connect to a power source, usually have some kind of display screen, and come with negative and positive cables to connect to your battery. Most trickle chargers will cost between $35 and $100, with the higher-end chargers providing more safety features. 

trickle charger

What Does a Trickle Charger Do?

A trickle charger does just what it says: trickle charges your batteries with the goal of keeping them fully topped off. Also called a battery maintainer, trickle chargers slowly emit approximately one to three amps. In some circuits there are small drains on the batteries as well that a trickel charger can keep up with.

If you plan on leaving your batteries sitting for long periods of time, be sure to pay attention to the capabilities of your charger. Some manual chargers simply emit a low amperage, but that’s about it. That means they don’t know when to shut off. 

Smart trickle chargers, however, have advanced capabilities such as switching into “float” mode to keep your batteries topped off. They even know when to turn back on when the battery starts to drain again. This prevents your batteries from either overcharging or going dead.

→ Suggested Reading: How Do I Charge My RV Battery?

Is It Better to Trickle Charge or Fast Charge?

If you have lithium batteries, the rate of charge doesn’t matter as much. 

However, for lead-acid, it can make all the difference. This has to do with the electrochemistry behind lead-acid batteries. When a lead-acid battery discharges, the lead electrodes turn into lead sulfate, and the electrolyte of sulfuric acid dilutes.

When it recharges, the chemical reaction reverses, turning the lead sulfate back into lead and the electrolyte into a stronger solution of sulfuric acid. During this process, a lead-acid battery can overheat and produce off-gassing if it charges too quickly, potentially damaging the battery in the process. 

battery maintainer

A good trickle charger can prevent this. Not only does it charge the batteries slowly, but it can also detect the state of charge and slow the amperage as the battery nears a full charge. This prevents off-gassing and battery damage. It also limits the risk of a battery explosion. Usually, lead acid can take a rapid charge at first but should slow for a trickle charge that takes a long time to finish up the charge.

When Should You Use a Trickle Charger? 

A trickle charger can come in handy anytime you need to store your batteries. Whether you’re leaving your car parked for an extended period of time, storing your RV for the winter, or want to prevent your boat batteries from going bad, there are a variety of reasons to invest in one. 

The type of batteries you own might influence your decision as well. Different batteries experience varying degrees of self-discharge rates. For example, lead acid batteries experience 10-15% per month self-discharge. Meanwhile, lithium batteries like Battle Born experience only 1-2% per month. 

Thus, factoring in the amount of time they’ll be sitting, the type of batteries you own, and the number of safety features you’ll need will help you choose the most appropriate trickle charger. 

→ Pro Tip: Check out how to choose the best marine battery charger for your boat.

trickle charger on lithium battery

Does a Trickle Charger Fully Charge a Battery?

Yes, a trickle charger can fully charge a battery; it will just take a very long time. Because trickle chargers only emit between 1-3 amps, you can expect to wait days for a fully charged battery. 

For example, a 1-amp trickle charger will take a full 100 hours to completely charge a dead Battle Born 100 ah Battery. This is why trickle chargers simply keep your batteries topped off. 

If your batteries are completely dead, we highly recommend using a regular charger to get them topped off quickly. On average, lithium batteries only take about two to three hours to charge when using the appropriate charger. Lead-acid batteries take about eight hours.

How Long Should You Leave a Trickle Charger on a Battery? 

Nearly all trickle chargers are designed to stay on your batteries for very long periods of time. This is because they’re for battery storage, which can last six months or more. 

However, if you want a “set it and forget it” battery charger, you might opt for an “automatic” or “smart” trickle charger. These devices generally have more safety features, including the ability to reduce the amperage they emit as the battery nears a full charge. This way, you’ll have peace of mind knowing that your batteries will stay topped off but never overcharge. 

Pro Tip: Depending on your battery setup and application, you may need some additional charger accessories to keep your system charged and ready for use.

Can a Trickle Charger Save a Battery? 

Yes! A trickle charger can save the life of a battery for several reasons. 

First and foremost, no battery should drain 100% of its charge. Lead-acid batteries are only supposed to experience a 50% discharge in order to maintain good health. Lithium batteries should probably only experience a 95% discharge before being recharged and it’s best not to let them sit completely discharged for long periods of time. Trickle chargers prevent the batteries from even coming close to these rates and thus help to uphold the integrity of your batteries. 

Not only that, but a fully drained battery can suffer more damage in cold weather. Thus, if you plan on storing your batteries in a cold garage all winter, a trickle charger can make all the difference when you return in the spring. 

Do you have any questions about trickle chargers? Drop them in the comments below!

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