What’s the Difference Between Trickle Chargers and Battery Maintainers?

A dead battery, whether in a car or piece of power equipment, is an instant killjoy. Here's how to prevent that with a trickle charger.

In my experience, there’s nothing more infuriating and disruptive than a dead battery. Like the time my 8,500-watt generator battery died in the middle of an ice storm, causing us to lose power for a week.

Because my wife worked from home, a running generator wasn’t a luxury. Even with a full-size 12-volt car battery charger and a portable jump starter, I had to use the pull cord to get this monster fired up. My first purchase — after replacing the battery, of course — was a battery maintainer.

Equally frustrating was the time my SUV had a slow electrical drain or “parasitic draw” that killed the battery every five or so days if it wasn’t driven. I kept a trickle charge on it until I figured out a loose ignition switch was keeping the vehicle ON.

Trickle chargers and battery maintainers keep batteries at the ready to start your car or power equipment, but they have different features and are used for different purposes. Here’s what you need to know.

What Is a Trickle Charger?

A type of six or 12-volt, low amperage (usually two to 10 amps) device used to slowly recharge a weak or dead battery.

Trickle chargers need to be watched. Once the battery reaches full charge, a standard trickle charger continues to charge. If left unattended, it will overcharge a battery, shortening its life.

Consider spending a little more money for a trickle charger with an automatic self-regulating “float” mode that stops once the battery reaches full charge. Or purchase a solar-powered one for camping.

When To Use a Trickle Charger

Trickle chargers are best for short term use to keep a weak battery charged overnight — say, on a vehicle that may sit unused for a week or so.

Remember, some devices in your vehicle are always ON, powering various computers and control modules even when the vehicle is OFF. These will drain a 12-volt battery. Trickle chargers maintain full charge on frigid nights that sap the life (and voltage) out of older batteries. Keeping older batteries fully charged can extend their life.

And a trickle charger can overcome a parasitic draw. If you don’t use a battery maintainer on your seasonal devices, boat, RV or motorcycle batteries, connect a trickle charger to them about a week before you plan to use them. This will recharge/refresh the battery.

Besides my SUV, I’ve used trickle chargers on 12-volt lead-acid car and deep-cycle golf cart batteries. They also can be used on 12-volt lithium-ion, absorbent glass mat (AGM) and gel-cell batteries.

Trickle chargers are not for jump-starting a dead battery.

What Is a Battery Maintainer?

A 12-volt battery maintainer works like a trickle charger, but it’s not the same. It usually outputs one amp or less to keep a battery charged. It can’t recharge a dead or depleted battery.

It works by automatically adjusting its power output to match the battery’s needs. It can also prevent overcharging by automatically turning itself off when the battery reaches full charge. Then it turns back on when it senses a drop in voltage. Unlike a trickle charger, it can stay connected to a battery indefinitely without the danger of overcharging.

When To Use a Battery Maintainer

These are best for long-term applications where a healthy battery needs to be kept fully charged for an emergency, hitting the road on your motorcycle on a rare sunny winter day, or for on-demand needs (i.e. a generator).

Trickle chargers are best for seasonal equipment (boats, personal watercraft, lawn tractors), motorcycles, dirt bikes, ATVs, off-road UTVs, RVs and classic or custom cars that may be driven only two or three times a year. They won’t keep a battery charged if the vehicle has a parasitic draw, and they won’t charge a completely discharged battery.

Once a battery is serviced and fully charged, battery maintainers work on the same battery types as trickle chargers- except for 12-volt lithium-ion batteries, which have a much lower discharge rates

And, according to NOCO technical support, you can use a battery maintainer on an EV 12-volt battery. Be sure to choose one compatible with EVs.

Bob Lacivita
Bob Lacivita is an award-winning ASE and General Motors auto technician, educator and freelance writer who has written about DIY car repairs and vehicle maintenance topics. His work has been featured in The Family Handyman, a Reader's Digest book and Classic Bike Rider magazine. He has been a career and technical educator for 25 years teaching automotive technology, as well as writing state, federal and organizational foundation grants. He also helped design a unique curriculum delivery model that integrates rigorous, relevant academic standards seamlessly into career and technical education.