Do you have a car battery sitting on a shelf in your garage, or a vehicle that you don’t drive?
Chances are, you’ve noticed car batteries slowly lose their charge when they aren’t in use.
Car batteries don’t need to discharge much before they become useless to a car, and recharging dead batteries can be time-consuming.
That’s where battery maintainers enter the picture: They are designed to give batteries just enough juice to keep them fully charged without overcharging them. This lets you keep batteries in storage indefinitely without worrying that they’ll need to be recharged or completely ruined when you go to use them.
Many battery maintainers are versatile enough to do double duties. They can recharge low batteries as well as maintain charged batteries. You can also find battery maintainers that will work with multiple kinds of batteries, such as 6V and 12V batteries. Many can detect the kind that’s attached to them and charge them accordingly.
Below is this year’s round-up of the 9 best battery maintainers that we reviewed out of the dozens that are available in 2021. We picked each because it outshined its competitors or fits a particular role better than the rest.
The 9 Best Battery Maintainers for 2021
1. Battery Tender Plus 021-0128 – Great Value
2. Schumacher SP1297 – Highest Rated
3. DieHard 71239 Platinum – Versatile
4. CTEK 56-864 MUS4.3 – Best Automatic
5. Schumacher SE-1-12S – Highly Versatile
6. Battery Tender 022-0185G-dl-wh – Most Popular
7. Schumacher SC1359 – Great Value
8. NOCO Genius G4 – Most Economical
9. Schumacher SC1319 – Most Affordable
- The 9 Best Battery Maintainers for 2021
- 1. Battery Tender Plus 021-0128 – Great Value Battery Maintainer
- 2. Schumacher SP1297 – Highest Rated Battery Maintainer
- 3. DieHard 71239 Platinum – Versatile Battery Charger and Maintainer
- 4. CTEK 56-864 MUS4.3 – Best Automatic Battery Charger
- 5. Schumacher SE-1-12S – Highly Versatile Battery Maintainer
- 6. Battery Tender 022-0185G-dl-wh – Most Popular Battery Maintainer
- 7. Schumacher SC1359 – Great Value Battery Booster, Charger, and Maintainer
- 8. NOCO Genius G4 – Most Economical Battery Maintainer
- 9. Schumacher SC1319 – Most Affordable Battery Maintainer
- How to Choose the Right Battery Maintainer – Buyer’s Guide
- The Bottom Line
1. Battery Tender Plus 021-0128 – Great Value Battery Maintainer
Its portability makes it handy as a charger you can take to a car.
It automatically selects its charging mode by detecting the condition of a battery once it’s connected to it.
It uses a smart microprocessor that only charges a battery when it’s needed, which avoids reducing its life by overcharging it.
The 021-0128 also comes with safety features like reversed polarity warnings and well-insulated connector cables.
Overall, though, we’d recommend this battery maintainer for anyone looking for a reliable product for use mainly to maintain charged batteries and occasionally to recharge low batteries when needed.
- Auto-detects battery condition
- Doesn’t “trickle charge” batteries
- Reversed polarity warning
- Low amperage rating
2. Schumacher SP1297 – Highest Rated Battery Maintainer
It has a well-designed case with inset LED display on the outside, and a microprocessor on the inside that controls its auto-detection and charging system.
It comes with well-insulated connector cables for car batteries and another set better suited to smaller batteries.
It also comes with a convenient hook attachment, so you can stay organized by hanging it up with other tools.
With a 3-amp charge rating, the SP1297 can bring low batteries up to a full charge in a reasonable amount of time, and the multi-stage charging system ensures that they aren’t over-charged or damaged.
It also includes safety features like reverse hookup detection, and it can automatically detect the type of battery being charged.
We recommend this battery maintainer for shops that need to maintain both 6V and 12V batteries and expect to recharge drained batteries often.
- Auto-detects 6V and 12V batteries
- Handy hook attachment
- Well-designed housing case and display
- Can’t be used as a battery booster
3. DieHard 71239 Platinum – Versatile Battery Charger and Maintainer
Like many modern products in this category, it has a microprocessor that detects the type of battery it’s connected to and handles the charging or maintaining automatically.
The housing is designed to prevent its display from getting cracked, and the LED display keeps you informed with helpful messages like “Connect Clamps” and “Fully Charged Auto Maintaining.”
It’s designed to be hung up with other power accessories or tools for easy organization.
It also comes with battery connector cables, ring connectors for long-term installation, and a cable for plugging it into a car’s 12V accessory outlet.
We liked the DieHard as well as we did Schumacher’s SP1297. It has accessories for maintaining batteries in cars that are in long-term storage, so we’ve included it in our line-up, too.
- Accessories for maintaining batteries in cars
- Safety features and smart multi-stage charging
- Not great for charging drained car batteries
4. CTEK 56-864 MUS4.3 – Best Automatic Battery Charger
Its no-nonsense housing is designed to be used outdoors and resists wet and dusty weather.
It forgoes the larger displays found on other battery maintainers, opting for simpler LED lights that indicate the charging stage that’s currently active.
It’s built for safety with features that prevent sparks, short circuits, and reversed polarity hookups.
It’s designed to recondition batteries, charge fully discharged batteries, and detect if a battery has lost the ability to hold a full charge. It does all of this using an automatic detection process and steps a battery through a patented 8-stage charge cycle.
We liked the extra mile the designers of CTEK’s MUS 4.3 went to give car owners a tool that handles multiple scenarios, from charging drained batteries in cold weather to maintaining batteries in storage.
- Detects the condition of acid-lead batteries
- Charges fully discharged batteries efficiently
- Designed for car batteries only
5. Schumacher SE-1-12S – Highly Versatile Battery Maintainer
Schumacher’s SE-1-12S was specifically designed for scenarios like this, functioning as a long-term battery maintainer.
It comes with a durable housing designed to resist hazardous substances it might encounter in a garage, and it delivers enough amperage to keep your batteries topped up for months.
The SE-1-125 also comes with many of the standard safety features that make modern maintainers easy to handle, such as spark and reversed polarity protection.
It comes with eyelet connectors that you can use to install it to battery terminals securely. You also get a handy bracket that you can use to mount the unit to a wall or workbench.
We recommend this product for storing cars and other equipment long-term.
- Designed to maintain batteries in any weather
- Sturdy housing resists corrosive substances
- Isn’t intended as a battery charger or booster
6. Battery Tender 022-0185G-dl-wh – Most Popular Battery Maintainer
With 1.5 amps of charging current, it can bring low batteries up to a full charge with a little patience and easily maintain 12V car batteries long-term. It uses a completely automatic charging process that consists of four stages that’s electronically controlled.
It’s designed to maintain acid-lead, maintenance free, and sealed batteries used by cars, ATVs, jet skis, lawn mowers, and other sports equipment.
Safety features include insulated connector clamps, reversed polarity detection, and a safety timer.
It’s built with a lightweight plastic housing that makes it easy to take anywhere you have a power outlet within reach and a battery to maintain.
We’d recommend this battery maintainer for a car and small vehicle owners who need to make sure their batteries are fully charged for long stretches spent under dust covers.
Any heavy duty charging or boosting or hostile work environment might call for a sturdier product with more amperage.
- Affordable and easy to use
- Maintains acid-lead batteries
- Not intended to be used to charge or boost drained batteries
7. Schumacher SC1359 – Great Value Battery Booster, Charger, and Maintainer
It’s designed primarily for car batteries, but it’s compatible with AGM, deep-cycle, and gel batteries as well as standard acid-lead batteries.
The SC1359 can perform rapid recharges with a 15-amp current or step its power down to 3 amps for maintenance cycles.
It auto-detects the condition and type of battery hooked up to it and has a multi-stage charging system to ensure battery life is preserved.
We liked the SC1359’s ability to charge and maintain batteries at a price point that’s not much higher than many battery maintainers that don’t excel at recharging dead batteries. If you don’t mind its larger size, it’s probably the best option we’ve reviewed for the typical car owner.
- Excellent charging amperage
- Reasonable price
- Not intended for long-term battery maintenance
8. NOCO Genius G4 – Most Economical Battery Maintainer
This product has charging banks and cables for up to four batteries at a time, and it has display indicators for each bank.
If you have multiple cars and small equipment batteries to keep at full charge during the off-season, this maintainer was designed to charge them all at once.
It works with 6V and 12V batteries and can deliver 3 amps of current to each charging bank simultaneously.
Like NOCO’s single-battery maintainers, it uses auto-detection and multi-stage charging to ensure that battery life is preserved year-round.
It comes with both eyelet connectors and insulated clamps that are convenient for long and short-term hookups. It also comes with NOCO’s safety features like spark-proof connections and reversed polarity detection.
This is a battery maintainer that we’d recommend for anyone who needs to keep several batteries charged long-term. It’s a time-saver and reasonably priced compared to single-battery maintainers.
- Charges and maintains four batteries simultaneously
- Charges low batteries reasonably well
- Not intended to charge or boost dead batteries
9. Schumacher SC1319 – Most Affordable Battery Maintainer
It doesn’t have the amperage you’d want to charge car batteries, but it can handle smaller batteries without any difficulty.
It can be fitted with eyelet connectors for long-term maintenance, and it comes with insulated clamps when you just need to perform a charge-up.
It keeps batteries charged using auto-detection technology and an efficient charging system that minimizes damage to battery life.
At 1.5 amps, it can maintain 6V and 12V batteries but charging low batteries will take some time if you hook it up to car batteries.
We recommend this battery maintainer for motorcycle and small equipment owners who don’t want to pay for the extra power of battery maintainers designed for cars.
- Designed to maintain small engine batteries
- Affordable price
- Isn’t intended to charge car batteries
How to Choose the Right Battery Maintainer – Buyer’s Guide
The battery maintainer that’s right for you will depend on the features you need and the budget you have to spend. There’s a good selection of battery maintainers available designed to fit different situations, so you’ll want to educate yourself about the specs and features commonly offered by these products.
Features to Consider
- Charging Performance: If you want a battery maintainer than doubles as a charger, then you’ll be interested in how fast it can recharge different kinds of batteries. Amperage is one indicator of this, but there are others as well.
- Voltage Compatibility: Another feature that’s important is the voltages that are supported by the battery maintainer. Some maintainers are designed for 12V car batteries, while others can handle several battery sizes. When they do support more than one voltage, check if the product automatically detects the battery voltage, or if you need to select it.
- Battery Types Supported: Beyond the voltage they deliver, batteries differ in how they are designed. Acid-lead batteries are the standard type of battery used for cars and trucks, but there are others. A battery maintainer needs to be designed to support the kind of battery you have to ensure that it doesn’t damage the battery by overcharging it.
- Diagnostics: Another feature to watch for when looking at battery maintainers are diagnostics. Some maintainers will detect when there is a problem with a battery, such as when it’s lost the ability to hold a full charge. They’ll indicate problems with warning messages.
- Safety: Battery maintainers often transmit high amperage currents to batteries that are dangerous if you are accidentally shocked. Safety features like insulated clamps and voltage regulators are also something to consider when comparing products. Many products are also designed to automatically detect when the polarity of their connectors is reversed on the battery.
Different Roles of Battery Maintainers
When we talk about battery maintainers, we’re actually talking about a particular role or purpose for a product, which is keeping batteries charged while in storage. Many of the products you’ll find do this in addition to other things. If you know you’ll need something to fill one or more of these other roles, then you’ll want to consider buying a product that can do all of them to get more bang for your buck. It’ll also help reduce clutter in your garage.
- Battery charger: Charging a battery that is low is different than maintaining a full charge. It requires higher amperage currents to bring a dead battery back to life, but charging is a slower process than boosting a battery.
- Battery boosters: Boosting a dead battery with enough current to start a car requires more amperage than charging a low battery. Boosters are typically kept in a car for emergencies. They also can recharge low batteries much faster than standard chargers.
- Diagnostics: A battery maintainer can also serve as a tester that detects when a battery has a problem that will prevent it from functioning properly.
The Bottom Line
Today’s market for battery maintainers continues to offer products that are great for different situations. Whether you have a car that you keep in long-term storage or winter sports equipment that sits for most of the year, there’s a maintainer designed with your needs in mind. We chose the best battery maintainers that solve the most common problems battery owners have, so we’ve ended up with a good cross-section of what battery charger manufacturers have to offer.
We were particularly impressed with Battery Tender Plus 021-0128 and NOCO’s Genius G4 as a multi-bank battery maintainer. Stay tuned for next year’s winners as battery charging technology continues to find new ways to serve our battery maintenance needs.