Best Trickle Chargers: You'll Get a Charge Outta This

Matthew Guy
by Matthew Guy

Top 8 Best Trickle Chargers

What did the bartender say to the set of jumper cables that walked into the bar? Why, he said “You’d better not start anything in here tonight,” of course!

Hey. I’m a dad and am allowed to make dad jokes.

But here’s the thing – there’s an excellent chance that natty set of thick 2-gauge jumper cables actually won’t start anything if you’re working with a battery that’s constantly flat. Constantly running a battery flatter than the Prairies is a one-way ticket to the town of No Start. That’s why trickle chargers were invented.

Designed to feed a small but measured amount of juice into a car battery, trickle chargers – also called battery maintainers – use electricity to replenish batteries at or near the same amount of self-discharge. Try to find one that shuts off at appropriate times, called a ‘float’ mode, so the battery doesn’t get overcharged like festival goers trying to buy a bottle of water.

Their most common use is to be connected when a car goes into winter storage, allowing the battery to remain at the ready for the first flick of the key next summer. Some also advocate the use of a trickle charger to boost a flat battery, since the gradual re-introduction of juice is easier on a battery than a sudden jolt. It takes a helluva long time, though.

We’ve gone through the options on Amazon and present our findings here. No more dad jokes, we promise.

Table of Contents

1. Editor’s Choice: BATTERY TENDER® Plus 1.25 Amp Battery Charger

This brand is one of the best known names in the segment, accruing thousands of real-world views, the vast number of which are positive.

It has the ability to switch between float to maintenance modes, meaning your battery won’t get overstuffed like a Christmas turkey. A quick connect harness is included in case your car’s battery is located in a hard to reach area. Reverse polarity protection saves on potentially expensive connection errors.


  • Excellent reviews, well-known name, automatic float mode


  • Won’t recharge a completely dead battery

2. Cheap n’ Cheerful: LST Trickle Battery Charger

This diminutive little scamp is small enough to be flung in a toolbox and not consume too much space. As such, it is truly meant for maintaining the charge on a battery that sits unused over time. An intelligent microprocessor (is there any other kind?), provides different states of charge such as a bulk action which feeds at its highest rated current until the battery is 80% full.

Compare this to an absorption mode, one in which the unit gradually dials back the juice until the battery is all charged up. Once it fills the battery, it switches over to the maintenance function. It has selections for 12 volt or 6 volt with an even dozen being the default.


  • Low price, compact size, float mode


  • Only a 10-foot cord

3. For the Pro: DEWALT 70 Amp Rolling Battery Charger

Like a good employee who’s on the ball, there are some trickle chargers that are capable of more than one task. This unit from Dewalt is a battery charger on wheels that can also act as a jumper pack to quickly zap a battery back to life if you need the car started right now. There’s also a USB port on board in case your smartphone is low on juice, too.

That’s all in addition to a household-style 120V AC outlet into which one can plug a power drill or waffle maker (what - you don’t have both of those at the ready in your garage?). Fully automatic high frequency charging delivers 3 stages, automatically switching from fast charge, to top-off, to shut-off mode. This is because charging up a battery is like filling a glass of water - the person doing the pouring needs to slow down as the glass fills to the top lest they make a terrible mess.


  • Multiple uses and settings, wheeled for easy setup, detailed user screen


  • Expensive

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

Weighing a svelte 1.3 pounds, this trickle charger from Black and Decker is used to keep batteries in stored vehicles and battery applications at optimal capacity during the off season - so don’t try boosting that dead project car with it, mmkay? It’s good for small voltage batteries in the likes of lawn tractors but also said to be fit for full-sized cars as well.

Owners can connect the battery charger and maintainer with the included battery clips or battery ring terminals. Charging automatically stops when battery is fully charged or topped off and switches to float mode monitoring to maintain charge. Built-in circuit protection guards against overcharging, reverse polarity, or short circuit. There’s also a built-in mounting bracket and one-year warranty.


  • Compact, cheaper than the dirt on which you’ve parked the car


  • Some reports of uneven charge supply

5. CTEK Silver Test & Charge

Here we find a charger for 12V batteries that feeds electricity at a rated 4.3 amps. Its sellers take care to point out this unit can be used to perform test programs in order to establish the condition and performance of a battery and vehicle’s charging system. In honesty, most trickle chargers can do this but are not designed to easily do so.

A series of eight LED lamps line up in a row like the pistons in an old straight-six BMW, illuminating to indicate the state of a battery’s condition. This is preferable to a simple on/off light as it tells the operator if they’re getting anywhere with their charging efforts. The charger is said to have a special reconditioning function that will revive and restore deeply discharged and stratified batteries, a task most others cannot perform.


  • Detailed readouts, able to work with very weak batteries


  • Supporting documentation seems to be at a premium

6. NOCO Genius G26000 Pro-Series

One of my childhood buddies wanted to put ‘genius’ as his future profession in our high school yearbook. Trouble was, he had to ask us how to spell it. True story. This trickle charger from NOCO has no such problems, managing to correctly spell its own name the first time out. This thing is a powerful, professional grade battery maintenance tool designed to recharge all types of batteries including those found in 24V systems.

Its 5-amp constant current setting brings the goods when all you want is a trickle charger. A so-called repair mode dances a electric jig to revive old batteries that have, up to that point, given up the ghost. This is the largest unit in the Genius line, providing the heavy to work as a booster pack in a pinch as well.


  • Several battery tools in one, works with 24V and lithium-ion systems


  • Heavier and more expensive than most

7. Cen-Tech 12V Automatic Battery Float Trickle Charger

If all you need is a quick hit to keep the battery in your not-oft used rig charged up, this might be the unit for you. Said to activate when it senses a battery reading below 12V and automatically shutting off when it reaches 12.4V, it seems to be a great solution to maintain the battery on a vehicle that suffers a parasitic draw or is simply stored for the winter.

Dead simple to operate, all one has to do is plug one end into the wall and clip the alligators to the positive and negative terminals on the battery in question. A dearth of readouts mean you’ll only know if the thing is working or not but if your only goal is to keep a battery juiced up so it’s ready to go once the snow is gone, this little outfit could deserve a place in your box of tools.


  • Cheap insurance, simple to use


  • Unlikely to help in an urgent situation

8. MOTOPOWER 12V Fully Automatic Battery Charger/Maintainer

This curiously capitalized tool is marketed as a battery maintainer, doling out power to all types of 12V lead-acid batteries, including flooded or modern sealed maintenance-free ones found in just about every vehicle on the road today. Manual operation and endless fiddling is not required; just plug it in and leave it as the unit automatically takes care of charging and maintaining duties.

Beyond that, it will monitor the battery voltage and maintain a proper level with a float charging current that should prevent overcharging. With SAE quick release connection options including ring terminals on a 7.5amp fused circuit or old-school alligator clips, this unit should be compatible with the vast majority of machines except for their weirdo French car your homeroom teacher drove 30 years ago.


  • Two-year warranty, very cheap


  • Won’t work as a booster, complaints of janky LED notifications


Can I leave a trickle charger on all the time?

A short answer would be, no, you can’t. The reason is, trickle chargers are dumb and continuously charge the battery at the self-discharging rate. Therefore, if you leave a trickle charger on for a long period, the battery may get overcharged over time and may get permanently unusable.

With that being said, if you are planning to leave your vehicle unused for a while, and don’t want its battery to get drained out due to non-usage, you may want to go for a float charger that regularly monitors the battery health, charges it when there is some drop in power, and automatically turns off when the battery is fully charged.

Can a trickle charger ruin a battery?

Yes, it can. Because trickle chargers are not smart enough to determine when a battery is full, they continuously send small amounts of voltage and amperes to the battery, without knowing when the charging is complete. If you leave such a charger connected for too long, the battery might get overcharged, and you may end up having a damaged one.

Therefore, it is advisable to turn off the charger manually once it has served its purpose, and your battery is ready for use.

What is the best amperage for a trickle charger?

The answer to this question majorly depends on the capacity of the battery that you want to charge. Usually, it is good to have a trickle charger with a supply of 10 percent to 20 percent of the total amperage of the battery. A noteworthy point here is that the lower amperes the trickle charger has the more time it would take to charge the battery, and the better the battery would perform.

How to Calculate the Amperage and Charging Time

As mentioned earlier, the charger should be able to charge at the rate of somewhere between 10 percent and 20 percent of the total capacity of the battery. Considering this:

Calculating Charging Current

For instance, if your car has an 80 AH battery, its charging current would be:

With 10 Percent Charging

(80 x 10) / 100 = 8 amperes

With 20 Percent Charging

(80 x 20) / 100 = 16 amperes

An Ideal (Theoretical) Charging Time

Charging Time with 8 Amperes Charging (in Hours)

80 / 8 = 10 Hours

Charging Time with 16 Amperes Charging (in Hours)

80 / 16 = 5 Hours

Calculating Charging Efficiency

Charging efficiency is the actual number of amperes that a battery receives from a charger. In the above example, it can be assumed that the 80 AH battery receives 8 amperes or 16 amperes from a trickle charger (10 percent or 20 percent) respectively. With these figures, the battery will get fully charged in 10 hours and 5 hours.

However, these values and time vary during practical implementation. This happens due to the resistance in the cables, carbon deposits on the terminals, etc. Therefore, it is considered that the actual amperes that a battery receives are around 85 percent of what a charger sends.

That said, the amount of current an 80 AH battery receives would be roughly around:

From 8 Amperes Charger

(85 x 8) / 100 = 6.8 amperes

From 16 Amperes Charger

(85 x 16) / 100 = 13.6 amperes

Keeping the above values in mind, the actual time that a completely drained 80 AH battery would take to get fully charged would be:

Charging Time from 8 Amperes Charger (in Hours)

80 / 6.8 = 11.76 Hours (Roughly 12 Hours)

Charging Time from 16 Amperes Charger (in Hours)

80 / 13.6 = 5.88 Hours (Roughly 6 Hours)

You can use this method to calculate the number of amperes your battery requires for charging, and the time it would take to get fully charged when using trickle chargers of different capacities. Nevertheless, the thumb rule remains the same, i.e., the lower the numbers of amperes are the longer your battery will last, and the more efficiently will it perform.

Is it better to trickle charge or fast charge?

While fast charging prepares a battery for use quickly and must be used in case of emergencies where you need to hit the road at the earliest, a trickle charger continuously charges it at an extremely low rate. Where the former helps you save your time, the latter ensures that the battery’s performance does not deteriorate and its health remains intact. Simply put, unless extremely necessary, it is always advisable to charge the battery with the lower numbers of amperes, and an efficient trickle charger gets the job done pretty well.

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: RazzAndBerry / 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

Join the conversation
2 of 4 comments
  • Brn Brn on Jan 20, 2022

    I have two of the Black & Decker maintainers ($20 for the first on and $25 for the second at Home Depot. Why do people flood to Amazon again?). I've kept one on my lawn tractor for about ten years now. It's allowed me to keep the same battery for that entire time. The other, I use as needed, perhaps on a car that will sit for several weeks. I've also used it to jump start "dead" power tool batteries and bring them back to life. These chargers have paid for themselves several times over.

  • Scoutdude Scoutdude on Jan 21, 2022

    A trickle charger is not a battery maintainer and a battery maintainer is not a trickle charger even though some have similar rated charging amperage. A trickle charger will maintain a constant voltage and current and it will over charge the battery if left on long enough. A battery maintainer will charge the battery to full and then automatically switch to float mode. If the battery discharges it will switch back to charge mode and top it back off.