Best Car Battery Chargers and Maintainers
Batteries for cars, trucks, RVs, boats, and other vehicles lose the charge over time due to the battery age, weather, battery self-discharge, parasite drain, or simply because lights or some similar load was left turned On.
While jump starters can help one crank the engine quickly, battery chargers can recharge the discharged battery and even can bring the dead battery back to life.
Also, when leaving a car or other vehicle for a longer period of time, it is a good practice to leave the battery connected to the battery maintainer in order to keep the battery fully charged even for months to come.
Published: January 13, 2022.
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Types of Car Battery Chargers/Maintainers
There are basically two types of car battery chargers/maintainers - manual and automatic car battery chargers.
Manual car battery chargers are practically a transformer connected to the Graetz/Diode bridge and a couple of capacitors to smooth out the output voltage - and that's it.
Obviously, manual car battery chargers are very reliable devices, since there isn't much that could break or malfunction.
However, manual car battery chargers have many drawbacks, including:
- charging current and voltage cannot be set accurately,
- very few manual car battery chargers feature temperature compensation sensor/probe,
- car battery type cannot be set,
- charging end voltage cannot be set properly, leading to overcharge or undercharge of the car batteries, etc.
Automatic car battery chargers/maintainers are microprocessor-controlled devices with many features and options required for proper charging and maintaining of car, motorcycle, RV, boat, and other starting, dual-purpose, and deep-cycle batteries.
In our article, we discuss only automatic car battery chargers and maintainers.
What to Look For When Buying Car Battery Charger
When looking for a new car battery charger, there are a few important things to consider:
- Voltage: obviously, the car battery charger and maintainer should support 12V batteries. But, if You have the need for charging 6V or even 24V batteries, consider the charger that supports those voltages.
- Charging Current: maximum charging current is the charging current during the bulk charging phase and it determines how quickly the battery will be recharged.
For example, if You have a 70 Ah battery discharged down to 50% DoD, such battery must be recharged with 35+ Ah in order to become fully charged.
In that example, a battery charger with a maximum charging current of 5 Amps will recharge such battery in 7-8 hours since batteries are not ideal charge storage devices.
- Supported Battery Types: most car batteries are still flooded/wet lead-acid batteries, although more and more cars are using AGM and Gel-Cell, maintenance-free batteries. Also, lithium batteries are becoming more and more popular.
So, if possible or required, go for the battery charger that supports both lead-acid (wet/flooded, Gel-Cell, AGM) and lithium batteries.
Note: some battery chargers allow the user to set the battery usage to "Standby/Float" and "Cycle Use" since lead-acid batteries feature different charging voltages depending on the battery use. If such modes are present, when charging car batteries go for "Standby/Float" - car batteries are anything but "Cycle Use" batteries.
- Desulfation Mode: when the batteries are deeply discharged, in order to recover such batteries, battery chargers must enter the so-called Desulfation Mode where spikes of voltages are sent to the battery in order to remove/dissolve hardened Lead Sulfate.
- Dead Battery Recovery: most car batteries are considered fully discharged when their voltage drops below 11.8V at room temperature. However, lead-acid batteries can be discharged down to 0V(!), which can even lead to cell reversal.
But, even such batteries can be recovered (if the Owner is that lucky!) up to 90-95% of their nominal capacity using battery chargers that feature so-called Force Mode - battery charge forces current into the battery, although the charge can't sense the battery properly due to the too low voltage.
Of course, there is no warranty of any kind that so deeply discharged battery will be recovered ...
- Cell Equalization: after fully charging the battery, some chargers may enter the so-called cell-equalization charging mode intended for equalizing the voltage/charge of individual cells. Cell-equalization charging mode is often combined with trickle charging.
- Trickle charge: after the microprocessor-controlled battery charger fully charges the battery, it enters trickle charge mode - the charger charges the battery with enough current in order to prevent self-discharge of the battery. Trickle charging mode is also known as the maintenance mode.
- Jump Charging: some battery chargers can send relatively strong currents (30-100 Amps, for 30-60 seconds) to the car battery in order to help the battery crank the engine. Note: this is not jump-starting the car, this is jump charging the battery! As the current flows into the battery, it builds a so-called surface charge that allows the user to hopefully crank the engine ones - just be sure to recharge the battery as soon as possible.
- Thermal Compensation: lead-acid batteries have a negative temperature charging coefficient - during summer, they should be charged using somewhat lower voltages in order to prevent overcharging, and during winter, they should be charged using slightly higher voltages in order to prevent undercharging.
A good battery charger should feature thermal compensation.
- Safety Features: since battery chargers and especially car batteries are able to provide strong currents, safety features are very important.
Most common and required safety features include short-circuit protection, overheating protection, overcharge protection, spark-proof design, and reverse polarity protection.
Some battery chargers also come with additional features, like Power Supply Mode or similar, but these additional features often have no direct relation with the charging of car batteries.
How to Use Car Battery Charger
The best way to use the car battery charger is to:
- check the car's manual regarding the battery charging using the battery charger or contact the car's dealership and ask them the same question,
- check the battery charger Owner's Guide/manual and follow the charging procedure as recommended.
Seriously - not all modern cars are "happy" when their batteries are being charged using anything but the built-in alternator. Generally, a car battery can be recharged when the car is turned Off, but just in case, check the car's manual - modern cars are loaded with various electronics and who knows what can go wrong if the external power supply is connected to the car's electrical system.
Most car battery chargers are connected first to the battery - connect red/positive clamp to the positive battery terminal, black/negative clamp to the negative battery terminal - and only then connect the battery charger to the mains power.
Note: some cars even have dedicated battery charging points and should not/cannot be connected directly to the battery.
To Disconnect the Car Battery From the Car's Electric System or Not?
In many situations, it is much easier to remove the car's battery and recharge it in the workshop or garage.
However, this is a big no-no in modern cars - at best, You will need an access code for the radio/multimedia system. But, there is also a great possibility that You will have to tow the car to the local car's dealership or workshop in order to unlock the car's security system, engine, ignition system, etc.
That is why some cars have a small dedicated battery that powers the car's electronics when the main battery is removed or fully discharged.
For short: do NOT disconnect the car's battery without previously checking the car's manual - better safe than sorry ...
Top Car Battery Chargers and Maintainers
Here is our list of top car battery chargers and maintainers - the most popular and the most wished-for units are chargers in the 3-8 Amps range since such battery chargers can safely recharge car batteries without overstressing them.
Weaker battery chargers can do that job as well, but charging the batteries with too weak currents lasts too long and can even shorten the battery life.
Strong battery chargers can quickly recharge the batteries, but not all batteries can accept charge at the same rate - too strong current can cause gassing, overheating and can permanently damage the battery.
Battery chargers are very popular devices and although there are so many models on the market, these models have distinguished themselves as being some of the best car battery chargers on the market.
NOCO GENIUS5 6V/12V 5-Amp Fully-Automatic Smart Battery Charger/Maintainer
NOCO GENIUS5 is a fully automatic 6V and 12V smart battery charger with a maximum charging current of 5 Amps.
NOCO GENIUS5 is able to charge both 6V/12V lead-acid (flooded/wet, Gel-Cell, and AGM) and 12V lithium batteries.
Cycling through the modes is very easy - nonetheless, when the unit arrives, be sure to read the manual. Also, it is recommended to keep the manual close to the unit, just in case.
The unit features a thermal sensor, ensuring accurate charging during hot and cold days.
The physical dimensions of the charger are 4.6 x 2.9 x 1.9 inches (~11.7 x 7.4 x 4.8 cm) and it weighs only 1.5 pounds (~0.68 kg).
NOCO GENIUS5 features very low voltage detection - down to 1V. Also, it features a special Force Mode, allowing the user to charge batteries discharged practically down to 0V!
NOCO GENIUS5 after recharging the batteries completely, automatically switches to trickle charge (Maintenance Mode) and can be left connected to the battery without the fear of overcharging the battery.
The charger comes with ~77 inches (~195cm) long DC cable (with clamps) and 171.7 Inches (~182cm) long AC cable.
Also, it comes with many safety features, including Short-Circuit protection, Open-Circuit detection, Overheating protection, Overcharge protection, Reverse Polarity protection and it is also a Spark-Proof battery charger.
NOCO GENIUS5 comes with a 3-year limited warranty.
For more reviews and recommendations, feel free to check the NOCO GENIUS5 6/12V 5-Amp Fully-Automatic Smart Battery Charger/Maintainer Amazon link (link opens in the new window).
Optima Digital 400 12V Performance Battery Charger and Maintainer
Optima Digital 400 battery charger and maintainer features a maximum charging current of 4 Amps (3 Amps for smaller batteries) and is optimized for charging Optima RedTop, YellowTop, and BlueTop AGM batteries, but it can be used to charge other batteries as well, including 12V wet/flooded and AGM lead-acid batteries, used in automotive, motorcycle, marine, light-industrial, power sport, RV and other applications.
The unit features physical dimensions of 7.1 x 3.9 x 2.7 inches (~18 x 9.9 x 6.9 cm) and it comes with 6 feet (~1.83 m) long AC and DC cables.
Optima Digital 400 is able to recover deeply discharged batteries, it features thermal charging correction, spark-free operation, reverse polarity protection, over-temperature protection, etc.
Optima Digital 400 battery charger comes with a limited 3-year warranty.
For more reviews and recommendations, feel free to check the Optima Digital 400 12V Performance Battery Charger and Maintainer Amazon link (link opens in the new window).
Ampeak 12V 2/10/25A Smart Battery Charger/Maintainer Fully Automatic with Engine Start
Ampeak 12V 2/10/25A battery charger is a rather versatile battery charger/maintainer which automatically detects the battery voltage and capacity, and automatically selects the best charge rate for the battery.
Also, the charging cycle automatically switches to float mode after fully charging the battery.
Ampeak 12V 2/10/25A battery charger is intended for all types of 12V lead-acid batteries, including wet/flooded, gel-cell, and AGM lead-acid batteries used in automotive, motorcycle, industrial, marine, RV, Powersports, lawn&garden, and other similar applications.
The battery charger also comes with Reconditioning Mode in order to improve the performance and operating life of batteries left uncharged for a longer period of time.
Ampeak 12V 2/10/25A battery charger comes with 18 months limited warranty.
For more reviews and recommendations, feel free to check the Ampeak 12V 2/10/25A Smart Battery Charger/Maintainer Fully Automatic with Engine Start Amazon link (link opens in the new window).
Schumacher SC1281 100 Amp 30 Amp 6V/12V Fully Automatic Smart Battery Charger
Schumacher SC1281 is a fully automatic smart battery charger intended for lead-acid 6V/12V batteries discharged down to 0V!
Schumacher SC1281 features a charging current between 2 and 6 Amps, with the battery selector, allowing the user to set the exact battery type (standard wet/flooded, AGM, Gel-Cell).
Also, the unit is able to provide a quick 30 Amps boost, helping the battery crank the engine. If that is not enough, Schumacher SC1281 is able to provide 100 Amps to help the user crank the engine.
Schumacher SC1281 also comes with the battery and alternator tester, helping to diagnose electrical problems.
Also, it is advertised as a "battery charger", Schumacher SC1281 is also a battery maintainer.
Schumacher SC1281 comes with a 1-year limited warranty.
For more reviews and recommendations, feel free to check the Schumacher SC1281 100 Amp 30 Amp 6V/12V Fully Automatic Smart Battery Charger Amazon link (link opens in the new window).
CTEK 40-206 MXS 5.0 Fully Automatic 12V 4.3 Amp Battery Charger and Maintainer
CTEK 40-206 MXS 5.0 is a simple to use, yet very efficient battery charger designed for charging, maintaining, and reconditioning of various 12V lead-acid batteries, including automotive and motorcycle standard wet/flooded and AGM batteries.
The unit is very easy to use - just connect it to the battery and wall power socket, set the charging program and the charger will do the rest.
The maximum charging current is 4.3 Amps.
CTEK 40-206 MXS 5.0 features temperature compensation, Desulphation, and Reconditioning Modes, it is a spark-proof charger with reverse polarity protection, short-circuit protection, etc.
CTEK 40-206 MXS 5.0 battery charger/maintainer comes with a 5-year limited warranty.
For more reviews and recommendations, feel free to check the CTEK - 40-206 MXS 5.0 Fully Automatic 12V 4.3 Amp Battery Charger and Maintainer Amazon link (link opens in the new window).
NOCO GENIUS10 6V/12V 10-Amp Fully-Automatic Smart Charger/Maintainer
NOCO GENIUS10 is a fully automatic battery charger/maintainer with a maximum charging current of 10 Amps and is intended for both 12V lithium and 6V/12V lead-acid batteries, including:
- 6V lead-acid wet/flooded and AGM batteries,
- 12V lead-acid wet/flooded and AGM batteries,
- 12V lithium batteries.
Also, it can be used for repairing 12V lead-acid batteries and as a 12V power supply.
Changing modes is very simple - just press the mode button and cycle through the modes.
Safety features include Short-Circuit protection, Open-Circuit protection, Overheating protection, Overcharge protection, Reverse Polarity protection, with the Spark-Proof operation.
Physical dimensions of the charger are (H x W x D) 7.1 x 3.6 x 2.3 inches (~180 x 92 x 59 mm) and it weighs 3.33 pounds (~1.5kg).
DC cables length is ~77 inches (~195 cm), with AC cables length of ~71.7 inches (~182 cm).
NOCO GENIUS10 battery charger comes with a 3-year limited warranty.
For more reviews and recommendations, feel free to check the NOCO GENIUS10 6V/12V 10-Amp Fully-Automatic Smart Charger/Maintainer Amazon link (link opens in the new window).
Optima Digital 1200 12V Performance Battery Charger and Maintainer
In many terms, Optima Digital 1200 is very similar to the Optima Digital 400 smart battery charger/maintainer.
The main difference between these models is in size - Optima Digital 1200 is larger and features physical dimensions of 10 x 7.5 x 6.5 inches (~25.4 x 19 x 16.5 cm), but it also features an auxiliary maintainer port and a USB charging port.
Due to the size difference, Optima Digital 1200 also supports a maximum charging current of 12 Amps (Optima Digital 400 up to 4 Amps).
Optima Digital 1200 battery charger can recover deeply discharged batteries, down to 1.25 volts.
Also, the charger comes with advanced safety features including spark-proof operation, reverse polarity protection, diagnosis of battery faults and failures to prevent overcharging, and similar.
Optima Digital 1200 battery charger comes with a 3-year limited warranty.
For more reviews and recommendations, feel free to check the Optima Digital 1200 12V Performance Battery Charger and Maintainer Amazon link (link opens in the new window).
NOCO GENIUS1 6V/12V 1-Amp Fully-Automatic Smart Battery Charger/Maintainer
NOCO GENIUS1 is an ultra-compact, affordable and versatile battery charger/maintainer, intended for charging smaller lead-acid and lithium batteries and for maintaining all sorts of lead-acid batteries.
NOCO GENIUS1 charger supports charging of:
- 6V lead-acid batteries including wet/flooded cell, Gel-Cell, enhanced flooded, maintenance-free, and calcium lead-acid batteries,
- 12V lead-acid batteries including wet/flooded cell, Gel-Cell, enhanced flooded, maintenance-free, and calcium lead-acid batteries,
- 12V AGM lead-acid batteries,
- 12V lithium batteries.
Also, NOCO GENIUS1 features Force Mode to recharge lead-acid batteries discharged even below 1V!
Safety features include Short-Circuit protection, Open-Circuit protection, Overheating protection, Overcharge protection, Reverse Polarity protection, with the Spark-Proof operation.
NOCO GENIUS1 comes with a 3-year limited warranty.
For more reviews and recommendations, feel free to check the NOCO GENIUS1 6V/12V 1-Amp Fully-Automatic Smart Battery Charger/Maintainer Amazon link (link opens in the new window).
Battery Tender Plus 12V Battery Charger and Maintainer - Model 022-0185G-DL-WH
Battery Tender Plus 022-0185G-DL-WH is an automatic 12V battery charger and maintainer with the maximum charging current of 1.25 Amps and is intended for charging smaller 12V lead-acid batteries (motorcycles, Powersports, tractors, power generators) and for maintaining almost all sizes of 12V lead-acid batteries found in cars, boats, yachts, Powersports, etc.
Battery Tender Plus 022-0185G-DL-WH is compatible with wet/flooded, AGM, and Gel-Cell 12V lead-acid batteries.
Also, it comes with reverse polarity protection and spark-proof operation.
AC cables feature a length of 6 feet (1.83 m), while DC cables are 4.5 feet (~1.37 m) long. The charger itself weighs 2 pounds (~0.9 kg)
Battery Tender Plus 022-0185G-DL-WH comes with a 5-year limited warranty.
For more reviews and recommendations, feel free to check the Battery Tender Plus 12V Battery Charger and Maintainer - Model 022-0185G-DL-WH Amazon link (link opens in the new window).
Car Battery Chargers Frequently Asked Questions (FAQ)
Here are some of the most common Frequently Asked Questions (FAQ) about car batteries and their charging:
Which car battery charger is best?
There is no such thing as "the best" battery charger - it all depends on the charging requirements, battery size, condition, car type, and similar.
Generally speaking, for 40-75Ah car, boat, tractor, light industrial, and similar starting, dual-purpose and deep-discharge batteries, advanced battery chargers with charging currents in the 3-8 Amps are "the best".
If unsure, go for 5 Amps battery chargers even if the battery capacity is 50+ Ah - such battery chargers are affordable, versatile, and do their job well.
Is it worth having a car battery charger?
If You have a garage where You can recharge your car's battery, then Yes, it is worth having a good car battery charger.
But, if You have to recharge the car battery from time to time although the car is regularly driven, take your car to the workshop since the battery is not being recharged properly by the car's charging system.
How long does it take to charge a car battery with a charger? How long does a 12V charger take to charge a car battery?
Charging time depends on the battery capacity, depth of discharge, and charging current.
For example, a fully discharged 60 Ah battery can be recharged in 13-15 hours using a 5 Amps battery charger.
Can you charge a dead battery with your car?
It depends on the actual battery voltage and the battery's general condition.
If the battery is not completely dead (down to zero or to just a few volts), the car's charging system can recharge the battery completely in a few hours of driving - in that case, turn Off any multimedia system, lights (if not required by the local laws) and similar loads in order to increase the charging current and to decrease the load on the car's charging system.
Will idling a car charge the battery?
Yes, but slowly ... very slowly ...
Which car battery charger should I buy?
The one that best suits your needs and requirements - if unsure go for the battery charger with the maximum charging current in the range of 0.1-0.15C.
Weaker chargers can be used, but don't go with too weak chargers.
Will a battery charger charge a completely dead battery? Can a completely dead battery be recharged?
First of all, for the charger to recognize the battery, the battery must have some voltage left. If the battery is "completely dead" (down to 0-1V), some battery chargers will recognize the battery, some will not.
Also, some chargers come with the manual "Force Mode", which allows them to charge the battery with a certain current even the voltage is very low - when the voltage increases, other charging modes are used to recharge the battery completely.
So, will a battery charger charge a completely dead battery - it all depends on the battery charger model.
Can a 12V charger charge a car battery?
If the car battery is 12V, then use a 12V battery charger intended for such batteries.
How do you bring a dead car battery back to life? How long to charge a battery that is completely dead?
The easiest way to bring the dead car battery back to life is to connect it to the smart battery charger that is able to recharge such batteries or that features Force Charging Mode.
After the battery's voltage increases from 0-1V to almost 10V, other charging modes are used in order to recharge the battery completely.
For example, if the brand new 55Ah battery is discharged down to 0V, it will take anywhere from 12-13 hours to 16-18 hours to completely recharge such battery using 5 Amps battery charger - battery reconditioning takes time ...
Few Final Words
When charging the car's batteries, whatever You do - stay safe. If unsure, always check the manuals and contact the car's dealership - towing the car to the workshop takes time and money, but it is cheaper than frying the car's electronics with the wrong battery charger, wrong settings of the battery charger, connecting the charger to the wrong charging positions and similar.
Remember that modern cars are computers with wheels :)