Best Battery Maintainers: Charge It

Matthew Guy
by Matthew Guy

Top 8 Best Battery Maintainers

Sauntering out to one’s vehicle and twisting the key (or jabbing the start button) only to come up with a whole handful of nothing is one of the automotive world’s most frustrating experiences. Dead batteries are the bane of a gearhead’s existence. Thankfully, most cars turn off their headlights or dome lights automatically these days. They emphatically did not when your author was a kid.

Storing a car (or recreation vehicle) over the winter months can also wreck a battery. That’s why battery maintainers were invented. They are designed to facilitate a gentle flow of juice to a battery so it is not flatter than a Midwest cornfield come summer. Maintaining that level of charge is also important.

Table of Contents

1. Editor's Choice: BATTERY TENDER® Plus 12V, 1.25A Battery Charger

We’ll lead off this post about battery maintainers with a product from BATTERY TENDER®. One of the better-known brands dealing in this type of tool, the specific product you see here is on the more expensive side of their ledger - but there’s a reason.

The ‘Plus’ version is a 1.25A battery charger designed to fully charge a battery and maintain it at proper storage voltage without the damaging effects caused by traditional trickle chargers that feed power into a battery whether it’s needed or not. Reverse polarity protection saves the dolts amongst us, while the quick-connect harness helps in hard-to-reach areas.


  • Great ratings from recent customers, automatic maintenance mode, quick connects


  • Power cords could be longer

2. CTEK Silver 4.3A Test & Charge

The product is advertised as combining a micro-processor controlled battery charger with an integrated battery and alternator testing function. Apparently, the charger has a special reconditioning function that will revive and restore deeply discharged and stratified batteries.

Declarations like ‘But wait, there’s more’ always raise the suspicions of this jaded author but comments left by customers seem to bear out the claims. Being able to recondition a battery that’s gone flat is worth the cash. Its float/pulse maintenance mode also makes the charger a good fit for long-term maintenance of your vehicle’s battery.


  • Compact size, big power


  • Pricey

3. Mroinge Automotive Trickle Maintainer 12V 1A Smart Automatic Charger

This option from a company with an inscrutable name is one of the most basic and straightforward battery tending units available. It’s essentially a household wall adapter and some leads.

Don’t knock it for that, though. One would imagine this could be the perfect solution for those of us parking our rigs in a very small space. There is a quick disconnect harness so owners don’t have to mess with unhooking the charger when repositioning the vehicle that’s being tended. It is listed as having overcharging protection for the battery to which it is supplying juice.


  • Very affordable, very easy to use


  • Two-foot leads are insufficient for most people

4. Suner Power 12v Solar Car Battery Charger & Maintainer

This solar-powered battery maintainer is definitely Greta-friendly, though it would be of little use in your author’s hometown where three feet of snow just fell in the span of about two days. But if you live in Phoenix, listen up.

Not everyone parks their vehicle close to a power source, so harnessing the power of the sun (that sounds like a cartoon villain’s M.O.) to charge and tend a battery is an inspired idea. Available in several different wattages, the unit is said to have a premium strong solar glass to withstand high loads plus a durable ABS frame to avoid impact damage.


  • Free power from that big orange thing in the sky


  • Won’t work in miserable climates

5. BLACK+DECKER Fully Automatic 6V/12V Battery Charger/Maintainer

This long-running brand is in the battery maintainer game with this rugged-looking but compact unit. It charges and maintains 12-volt or 6-volt batteries with easy connect battery clips and O-ring terminals. It’ll cease charging automatically when the battery is fully charged or topped off, switching to float mode monitoring.

Weighing 1.3 pounds, this battery maintainer is less than a foot long, meaning it should store easily in a cubby or down in the spare tire wheel well. Over 4,500 reviewers have given this thing a 4.1 star rating, with the majority of them praising its ability to keep the battery of their ATV or motorcycle in good nick.


  • Sensible price, typical polarity and overcharging features


  • Might be best for smaller batteries

6. Schumacher 1.5A 6/12V Fully Automatic Battery Maintainer

Insofar as we can tell, the brand name on this battery maintainer has nothing to do with a certain seven-time F1 World Champion. Its auto voltage detection automatically determines if it is talking to a 6V or 12V battery. Both clamp and ring harnesses are included.

The seller asserts it is great for motorcycle, power sport, and boat batteries. This means one should shop around if you’re looking for a unit to tend to the power needs of your Power Wagon or F-450 pickup truck. A float mode automatically maintains optimum battery charge once it is at the proper levels.


  • Light, compact, affordable


  • Not recommended for big vehicles

7. Foval Automatic Trickle Battery Charger 12V

Here’s another in-line style battery maintainer, shipped with quick disconnects and an assortment of alligator clips and o-ring connectors. Measuring only 3.9 inches in length, it’s easy to fling this in the glovebox of your car until it’s needed. Also, we’re pretty sure Foval was a villain on one of the Star Trek series.

According to the ad, this tender plays nicely with all lead-acid, flooded or sealed maintenance-free batteries. Like a good Hollywood rehab center it follows a 4-step program, working its way through initialization, bulk charge, absorption mode, and finally float mode. The paparazzo isn’t interested in what Foval had for lunch, however.


  • Very small size


  • Intended for recreation vehicles

8. NOCO GENIUS2D, 2-Amp Direct-Mount Onboard, 12V Charger/Maintainer

We’ll end our post with this stouter-than-others unit from NoCo, a brand which popped up as recommended by shoppers who were carping about other tenders they felt didn’t work properly. Said to detect sulfation and acid stratification, this thing should rejuvenate a weak battery in addition to maintaining a strong one.

Plenty of customer feedback and real-world photos show some people semi-permanently installing this unit in a safe place under the hoods of their cars, occasionally plugging it into an electric source when parked in order to keep a 12V battery in good shape. Compliments abound about the product construction, including a design which does not allow the intrusion of water.


  • Enthusiastically positive reviews, great for a full-sized car


  • On the expensive side

Which battery maintainer is best?

Among all the other battery maintainers that are available in the market, Battery Tender Plus 12V Battery Charger and Maintainer has some pretty decent reviews on Amazon. The device is compatible with almost every 12V flooded, gel cell, AGM, and lead-acid battery types, and comes with a 10-year warranty along with lifetime customer support to ensure a safe purchase, and smooth and convenient usage. Furthermore, the built-in LED indicators help you assess the state of charging so you can know when the vehicle is ready to hit the road.

Do battery maintainers really work?

Yes, they do. In fact, they are a must-have entity for every car owner. Because battery maintainers automatically start charging as soon as the battery gets slightly discharged, and get back to standby mode post fully charging, they prevent the battery from dying, thus significantly increasing its life by checking and maintaining its health status.

Can you leave a battery tender on all the time?

Yes, if need be, you can. Because a battery tender charges at a lower voltage, and automatically cuts off when it detects a full charge, it doesn’t harm the battery in any manner if left on permanently. In such a scenario, as soon as the battery gets slightly discharged due to non-usage for a long time, a battery tender automatically turns on and starts charging the battery. This cycle goes on continuously, until the battery tender is turned off.

However, if you want, you can turn the device off when not in use to save electricity which is wasted otherwise.

What is the difference between a battery tender and a battery maintainer?

To understand the difference between the two, it’s important to know how a battery charger works. The functioning of all three, i.e., a battery charger, battery tender, and battery maintainer are explained below:

Battery Charger

A battery charger is a device whose one end is connected to a wall power outlet or a power bank, and the other side to the battery in question. Once connected and turned on, a battery charger charges the chemical structure of the battery at a constant rate that may fall anywhere between 14.2.0V and 14.4V.

Once the battery is fully charged, the charger must be disconnected manually to prevent overcharging that may damage the battery, and make it permanently unusable.

Battery Tender

A battery tender is also a battery charger but with some sophisticated characteristics. While a battery charger continuously throws the charging current to the battery regardless of its charge state, a battery tender starts charging only when it detects that the battery is discharged. Also, a battery tender charges at a lower voltage, i.e., somewhere from 13.3V to 13.5V to avoid overheating.

As soon as the battery is fully charged, the battery tender automatically stops the charging process, thus preventing any damages to the battery that it may encounter otherwise. Because of this nature, a battery tender can be left turned on and connected to your battery for comparatively longer durations.

Battery Maintainer

A battery maintainer is a piece of equipment that has the characteristics of both a battery charger and a battery tender. This means, in addition to focusing merely on charging at a decent voltage, the device also maintains the health of the battery by detecting and automatically cutting off the flow of the current when the battery is fully charged.

Because battery tenders and battery maintainers do more or less the same job with a slight difference in their characteristics, the two terms are often used interchangeably.

From time to time, TTAC will highlight automotive products we think may be of interest to our community. Plus, posts like this help to keep the lights on around here. Learn more about how this works.

(Editor’s note: This post is meant to both help you be an informed shopper for automotive products but also to pay for our ‘90s sedan shopping habits operating expenses. Some of you don’t find these posts fun, but they help pay for Junkyard Finds, Rare Rides, Piston Slaps, and whatever else. Thanks for reading.)

[Main photo credit: kurhan / Product images provided by the manufacturer.]

Matthew Guy
Matthew Guy

Matthew buys, sells, fixes, & races cars. As a human index of auto & auction knowledge, he is fond of making money and offering loud opinions.

More by Matthew Guy

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 1 comment
  • 28-Cars-Later 28-Cars-Later on Dec 29, 2021

    Generally speaking a battery tender is a good idea if your car is garaged and its "newer". I'm learning some of the newer cars (00+) can get all jacked up if you let them sit with a dead battery. Another fun fact I recently read is you cannot jump an R129 Mercedes SL as it can fry some expensive roof component. I suppose Mercedes expected its [original] buyers to have them on tenders or use the regularly then the heck with them.

  • Jalop1991 "why did the governor veto a bill to give me free gummint money?"
  • Jalop1991 absolutely. I'm probably coming into a 31 Model A, and there's a great retrofit system for that. It makes a bunch of sense.
  • TMA1 Been thinking about getting one of these for my mother. Skip the AWD and DSG, the FWD comes with an 8-spd. Good size vehicle for a woman who wants a SUV and has a small garage. Much better view outwards than the Mazda CX-30 I was looking at. Wish it had a power tailgate though - she's short.
  • Ajla Mustang.
  • Slavuta 2.3 mustang auto was quick enough but I didn't like it. Is this Ford still comes with Aluminum body parts? Because paint used to peel off. I like more classy Nissan cockpit. Both are not nearly perfect.