The Five Best Car Battery Chargers – Buyer’s Guide

Best Car Battery Chargers

One of the most depressing things is going to your car or motorcycle that you have stored in your garage for a sunny day — only for it not to start when you most need it because the battery has gone flat.

Having a car battery charger always available in your garage is incredibly handy for making sure this disaster never happens!

But choosing the best car battery charger is tough. Which is the most reliable? Which is car battery charger is best for your car or motorcycle’s battery to keep it healthy? Which chargers can work in any conditions — and withstand moisture, freezing cold, and high heat? What’s the best car battery charger for your car?

That’s why I put together this guide to the five best car battery chargers for your garage — updated as of 2020.

With a battery charger, you don’t have to worry about changing out your vehicle’s battery every time it begins to run low. Even better, many of the best battery chargers have a jumper function — so you can take them with you in case you’re at risk of being left stranded.

In this guide, I highlight

  • What to consider when buying a car battery charger
  • What makes the best ones good
  • Some extra car battery charger features you might not have thought about

We’ve also written extensively about the best car jump starters.

Contents

Best Car Battery Chargers of 2020

To help you make a decision, below is a summary table of the best car battery chargers we’ve tested.

We’ve included the most important information you might need to make your decision, including

  • Voltages (whether they can do 6V)
  • Current (from trickle through to massive industrial current)
  • Special features (e.g. water resistance)
  • Warranty

Name
CTEK MULTI US 7002 (Editor's pick — Best overall)
Schumacher SC1353 (Best Heavy Duty)
NOCO GENIUS10 (Best compact)
BLACK+DECKER BC25BD (Best Medium Heavy Duty)
Schumacher SP1343 (Best cheap trickle/float charger)
Image
CTEK (56-353) MULTI US 7002 12-Volt Battery Charger,Black
Schumacher SC1353 200 Amp 40 Amp 12V Fully Automatic Smart Battery Charger with Engine Starter, Boost, and Maintainer for Cars, Trucks, SUVs, RV Batteries
NOCO GENIUS10, 10-Amp Fully-Automatic Smart Charger, 6V and 12V Battery Charger, Battery Maintainer, Trickle Charger, and Battery Desulfator with Temperature Compensation
BLACK+DECKER BC25BD Fully Automatic 25 Amp 12V Bench Battery Charger/Maintainer with 75A Engine Start, Alternator Check, Cable Clamps
Schumacher SC1343 1.5A 6/12V Fully Automatic Battery Maintainer
Voltage & Current
12V only, 7A
6V/12V, 40A (plus 200A jump start)
6V and 12V, 10A.
12V, 25A
6V/12V, 1.5A
Portable
Features
Highly compact. Safety features. 8-stage charging.
Industrial strength. 200A jump start. Battery and alternator tester.
Water-resistant. Can charge from flat. Lithium ready. Very portable.
Heavy duty semi-portable. 75A starter current.
Trickle/float mode. Very compact
Rating
Reviews
1,390 Reviews
58 Reviews
5,602 Reviews
3,239 Reviews
1,360 Reviews
Warranty
5Y limited
3Y
5Y Limited warranty.
1Y
2Y
Name
CTEK MULTI US 7002 (Editor's pick — Best overall)
Image
CTEK (56-353) MULTI US 7002 12-Volt Battery Charger,Black
Voltage & Current
12V only, 7A
Portable
Features
Highly compact. Safety features. 8-stage charging.
Rating
Reviews
1,390 Reviews
Warranty
5Y limited
Name
Schumacher SC1353 (Best Heavy Duty)
Image
Schumacher SC1353 200 Amp 40 Amp 12V Fully Automatic Smart Battery Charger with Engine Starter, Boost, and Maintainer for Cars, Trucks, SUVs, RV Batteries
Voltage & Current
6V/12V, 40A (plus 200A jump start)
Portable
Features
Industrial strength. 200A jump start. Battery and alternator tester.
Rating
Reviews
58 Reviews
Warranty
3Y
Name
NOCO GENIUS10 (Best compact)
Image
NOCO GENIUS10, 10-Amp Fully-Automatic Smart Charger, 6V and 12V Battery Charger, Battery Maintainer, Trickle Charger, and Battery Desulfator with Temperature Compensation
Voltage & Current
6V and 12V, 10A.
Portable
Features
Water-resistant. Can charge from flat. Lithium ready. Very portable.
Rating
Reviews
5,602 Reviews
Warranty
5Y Limited warranty.
Name
BLACK+DECKER BC25BD (Best Medium Heavy Duty)
Image
BLACK+DECKER BC25BD Fully Automatic 25 Amp 12V Bench Battery Charger/Maintainer with 75A Engine Start, Alternator Check, Cable Clamps
Voltage & Current
12V, 25A
Portable
Features
Heavy duty semi-portable. 75A starter current.
Rating
Reviews
3,239 Reviews
Warranty
1Y
Name
Schumacher SP1343 (Best cheap trickle/float charger)
Image
Schumacher SC1343 1.5A 6/12V Fully Automatic Battery Maintainer
Voltage & Current
6V/12V, 1.5A
Portable
Features
Trickle/float mode. Very compact
Rating
Reviews
1,360 Reviews
Warranty
2Y

1. CTEK MULTI US 7002 – Best Overall 12 Volt Car Battery Charger and Maintainer

CTEK is one brand on our list that has actually earned a near sterling reputation in the world of battery chargers.

CTEK not only focuses on power transferal products, it actually specializes in battery chargers.

In fact, it is worth noting that the CTEK car battery charger is a slightly modified version of OEM car battery chargers that are included with the purchase of high-end luxury cars.

That said, the focus of this charger is a bit more narrow than some of the other car battery chargers on our list.

Energy

When it comes to car battery chargers, too many people pay far more attention to the numbers on the charger than how the charger provides energy. This usually is not much of an issue, but it can actually make a big difference depending on the battery. Some batteries are more sensitive than others and require the energy itself to be of a “higher quality” or else it could damage the battery cells. As a workaround, the CTEK MULTI US 7002 makes it a point to provide the cleanest energy possible, so you do not have to worry about whether or not it’s damaging your battery.

Protection

While the CTEK MULTI US 7002 provides some of the cleanest (noise-free) current out of all the car battery chargers on our list, it also has a number of fail-safe features to ensure that even if the energy itself is clean, no other malfunctions can damage your car battery.

For instance, the CTEC 70002 comes with reverse polarity protection, which actually protects both the car battery in question as well as the CTEK MULTI US 7002 from accidental reverse connection. The CTEK charger’s safety features mean you can leave it indefinitely, which is perfect for DC battery-powered electronics arrays.

Specification

  • Brand: CTEK
  • Model: 56-353
  • Product Dimensions: 7.5 x 3.5 x 1.9 inches
  • Item Weight: 1.76 pounds
  • Voltage: 12 volts
  • Current: 7A

PROS:

Is the smallest car battery charger reviewed
Is a less expensive battery charger
Has reverse polarity protection
Has 8-step charging system
Safe to leave connected
Has 2 different connectors
Has different modes
Provides indicator lights
Produces clean electricity

CONS

Only charges single voltage
Only charges lead acid batteries
CTEK - The Smartest Battery Chargers in the World

2. Schumacher SC1353 – Best Heavy Duty Car Battery Charger and Jump Starter

Schumacher is a fairly well-established company in the car battery charger market that has earned one of the better reputations.

Part of the reason for this reputation comes from the fact that the company not only makes a solid product, but they do so at different levels of the market. For instance, there is a fairly big difference between what someone who needs a car battery charger for their own personal car and someone who needs a car battery charger for larger vehicles, numerous different types of vehicles, or simply a large number of batteries for whatever person.

This is where the Schumacher SC1353 comes into play and is why it is rated as the best industrial car battery charger on our list.

Options

One thing that most people forget about when they consider industrial car battery chargers is the fact that there are a multitude of different types of batteries out there. While industrial car battery chargers may have been made to handle serious levels of amperes and voltages, they are also often designed to simply handle virtually every vehicular battery you might run across. That is why the Schumacher SC1353 can actually charge batters that feature 2 different voltages and can do charging at an astounding 4 different amperages. This means that regardless the battery output or its input limitations, the Schumacher SC1353 should be able to charge nearly any and every large voltage battery that you come across.

Build

While the sheer number of options with the Schumacher SC1353 is impressive, just as impressive with this car battery charger is its build quality.

Many of the other car battery chargers we reviewed have opted for a smaller, more portable profile to make them more attractive to the average consumer.

Of course, someone who needs an industrial car battery charger is likely not the average consumer. That is why the size and weight of this car battery charger is actually a benefit to its intended market as opposed to inconvenient to the average consumer.

On top of that, this car battery charger also has a built-in, included dolly to make moving the Schumacher SC1353 from one place to another much easier.

Specification

  • Brand: Schumacher
  • Model: SC1353
  • Product Dimensions: 12.9 x 13.6 x 19.7 inches
  • Item Weight: 31.4 pounds

PROS:

Charges 2 different voltages
Charges 4 different amperages
Has its own dolly
Has a cooling fan
Comes with numerous charge settings
Easy to use
More durable than most
Has an amperage gauge
Has a timer

CONS

Is the most expensive car battery charger reviewed
Is the largest car battery charger reviewed

3. NOCO GENIUS10 – Best Versatile Smart Car Battery Charger for Multi-Stage Charging, Dead Batteries, and Marine Use

NOCO is one of the lesser-known but very old brands (over a hundred years old, founded in the US in 1914) that has a wide variety of really high-quality car (and boat and motorcycle) battery chargers available with some unique features.

NOCO totally specializes in battery chargers and accessories — that’s all they do. So they’re quite customer-focused and feature-focused, even after so long a history. Which is why the NOCO Genius10 is so great — it can do a lot of things, and it does it in a compact package.

We really like a lot of NOCO chargers, but the one we recommend is the Genius10, a 10-amp charger that suits a variety of different use cases. It’s an update on the G7200 which we had previously listed as our pic from NOCO.

Marine

While there are specific marine battery chargers out there, they are often significantly more expensive than car battery chargers due to the smaller, niche, luxury market of boats. If you would like to save some cash while still getting a stellar product, the NOCO Genius10 was designed to serve double duty as both a land and sea battery charger and even makes it a point to advertise this. The reason that the NOCO Genius10 is so well-suited to this task is because it features an IP65 rating. What this means is that the NOCO Genius10 can withstand jets of water splashed on it. While this is not a submersion level of protection, it should be plenty for most water activities.

Versatility

Another benefit of the NOCO Genius10 is the fact that you can use it for pretty much any commercial vehicle that’s 6 or 12V. The NOCO can even charge Lithium batteries — something that many cheaper batteries can’t do.

Finally, the NOCO Genius 10 is quite small (only 5 inches at its longest dimension, and weighing only 3.5 pounds), meaning you can take it out of your garage when you want to take it with you.

Specifications

  • Brand: NOCO
  • Model: Genius10
  • Product Dimensions: 4.3 x 5 inches
  • Item Weight: 3.5 pounds
  • Batteries: 1 Lithium Metal batteries
  • Folding: No
  • Cover Included: UltraSafe Battery Charger, Battery Clamps, Eyelet Terminals, User Guide, 5-Year Limited Warranty
  • Current: 10A
  • Voltage: 12V, 6V

PROS:

Charges 2 different voltages
Delivers 7A of current
Compatible with numerous charging systems
Charges quicker than most
Has an incredibly compact design
Features numerous indicators
Has 2 different connectors
Is IP65 water resistant
Has reverse polarity protection

CONS

Is a more expensive car battery charger
Does not charge drained battery
How to change modes on your NOCO GENIUS10

4. BLACK+DECKER BC25BD – Best Portable High-Current Car Battery Charger for AGM Batteries

When it comes to car battery chargers, BLACK+DECKER is likely not the first name that you think of. Though you might know the brand for toasters and home appliances, you would be pleased to know that their car chargers are not only affordable, but also really robust and high-quality.

This BLACK+DECKER battery charger isn’t tiny, but it’s still portable via its large handles. That’s understandable because it provides an impressive 25A of current for a relatively low-cost charger.

This charger can work on a variety of batteries, including AGM, GEL, or WET automotive or marine batteries. The only downside is that if you want to charge the batteries in your fancy RV, this charger can’t charge lithium batteries — if that’s what you have.

Replenish

Arguably, the best reason to choose the BLACK+DECKER BC25BD is the fact that over the course of time and through repeated uses, it can actually improve the efficiency and lifespan of your battery. Basically, the BLACK+DECKER BC25BD can alter how it distributes the power to your battery such that the cells which were otherwise depleted will shake off some of the contaminants and be usable once again. That said, this will not take a completely depleted battery and restore it life once again, but it will still be able to help usable batteries keep their life a little bit longer than they otherwise would have and is not a feature found on even some of the more renowned products we reviewed.

Convenience

Considering that BLACK+DECKER is a brand that is designed for consumers and not professionals, it only makes sense that they would spend a bit more time providing a number of features that can make their product stand out from the pack – even if those features do not actually improve the product at a fundamental level.

That said, these features are legitimately useful for consumers who might not want to fool with the issues. For instance, the BLACK+DECKER BC25BD comes with both a jump start feature to jump-start your vehicle when the battery is dead, and an alternator checking feature to make sure that the battery is the problem in the first place.

Specification

  • Brand: BLACK+DECKER
  • Model: BC25BD
  • Product Dimensions: 9.8 x 14.8 x 5.8 inches
  • Item Weight: 8.25 pounds
  • Amperage: 25 A
  • Voltage: 12 volts only

PROS:

Is fairly compact
Is a less expensive car battery charger
Reconditions old batteries
Has 3 separate charge settings
Has reverse polarity protection
Comes with an LCD display
Provides alternator check
Has jump start feature (75A)

CONS

Can only charge 12V batteries
Battery reader is finicky
Cannot charge lithium batteries
Black & Decker 25 Amp Battery Charger with 75 amp Engine Start

5. Schumacher SP1343 – Best Cheap Car Battery Trickle Charger for Home

When it comes to power management, there are few companies that saw which are able to compete with the sheer gravitas of Schumacher. That’s why it’s our top recommendation for a heavy duty charger, above.

But even though Schumacher makes a wide variety of industrial equipment, they also make trickle chargers that you can use to keep your battery maintained for long periods of time.

Schumacher makes trickle chargers that come in 1, 1.5, 3, and 6 Amps. We think the 1.5 Amp one is a great balance between price and functionality for a car battery charger left to keep your car or motorcycle charged for a long period.

In addition to being affordable, the 1.5A variant can charge at 6V too. Even if you don’t need that now, the versatility will come in handy.

Control

Even though the Schumacher SP1343 is by far the least expensive product that we reviewed, it actually offers some legitimately impressive control features. That said, it is not the control settings that are impressive but the mechanism which allows them. Specifically, the Schumacher SP1343 is microprocessor-controlled. It keeps track of the battery’s energy readings to make sure it doesn’t over-supply the battery and damage it, but keeps feeding it voltage to reach its full potential.

Protection

This microprocessor in the Schumacher SC1343 actually does more than simply track the energy readings--it also has one of the more rare types of protection that we saw. Basically, this car battery charger is able to withstand higher temperatures than most of the others on our list — which is a big deal as that is arguably the most common type danger facing a car battery charger.

On top of that, the microprocessor is also able to make sure that the Schumacher SC1343 does not run the risk of overcharging the battery, so you can leave connected the whole time. The microprocessor essentially gives the Schumacher SC1343 car battery charger the ability to have multiple charge settings.

Specification

  • Brand: Schumacher
  • Model: SC1343
  • Product Dimensions: 7 x 7.5 x 11 inches
  • Item Weight: 1.3 pounds
  • Amperage: 1.5A (others available)
  • Voltage: 6, 12 volts
  • Folding: No
  • Vehicle Service Type: Motorcycle, snowmobiles, all-terrain-vehicles

PROS:

Is the least expensive battery charger reviewed
Can charge 2 different voltages
Has different charge settings
Has 2 different connectors
Is a more compact car battery charger
Has a microprocessor
Charges quicker than some
Safe to leave connected
Has temperature protection

CONS

Only provides a single amperage
Designed to mostly maintain, not good if you’re in a hurry
Schumacher Battery Charger (Review SC1303)

Buyer’s Guide — How to Choose the Right Car Battery Charger

Type

While all of the products that we reviewed are car battery chargers, some chargers you come across may actually be a bit more specialized in their function. While they can all charge batteries, it may be that they’re suitable for other tasks (sometimes more than a car battery charger).

Quite often, this has more to do with how the car battery charger interacts with the battery when it is at different levels of being charged. The important thing to remember is that not all types of battery chargers are intended to charge a battery that is completely drained. Similarly, some battery chargers are meant to be used on older batteries that might otherwise be on their last leg.

Maintainer – This is the “middle ground” when it comes to the different types of battery chargers. It will not recharge a completely drained battery like a standard battery charger will, nor will it focus on heavily at restoring the batteries cells to their former state. Instead, this type of battery charger is meant to keep a battery that still has some juice left in it from completely running out as well a providing some cell maintenance while it does.

Keep in mind, a battery charger maintainer cannot usually handle some of the more extreme types of battery issues. On top of that, individual models are often limited in the type of batteries they can charge.

Charger – This is the standard type of battery charger and the one that most people should look for unless you have a fairly particular circumstance. This type of charger comes in the most varied permutations, including the most different types of batteries, the most voltages, and the most amperages. Ultimately, if you have any kind of car battery, then there is a standard charger out there that can handle it. One of the great things about a standard car battery charger is that they are designed to be able to charge a battery that has been completely changed. On top of that, standard car battery chargers are often less expensive than some of their counterparts, and they are also made for a wider range of vehicles than some of the other types of car battery chargers.

Restorer – This is the least common type of battery charger, and, in truth, the charging function is simply a necessity of this product’s actual function. Essentially, a restorer is able to break down the various contaminant build-ups in the battery’s cells so that they can once again consistently hold an electric charge.

This is usually accomplished through various manipulations of the charging energy, which then either realigns the cell’s constituents or breaks down the byproducts. This is generally the most expensive type of car battery charger and is truly only necessary if you have a large number of vehicles and batteries that will regularly need to be restored and charged. If you do not own a fleet of vehicles or have other uses for that many batteries, then this is not a worthwhile purchase.

Voltage

The different voltages that a car battery charger can put out will have a big impact on whether or not it is appropriate to use with your vehicle. For instance, car battery chargers are used to charge the batteries for more than just cars. Trucks and even marine crafts all use car battery chargers--though many of them may actually use a battery that is not the standard 12V that a car will generally use.

Thankfully, there are plenty of car battery chargers on the market that provide a wide range of different battery voltages that it can distribute. In fact, there are plenty of battery chargers can charge voltages as low as 6V and as high as 48V. This means that car battery chargers can conceivable service vehicles ranging from as big as industrial vehicles to smaller vehicles like go-karts or other smaller vehicles.

Amperage

Much like with voltages, there is a wide range of amperages that different batteries required. That said, much like the wide range of voltages that a car battery charger can provide, so too do many car battery chargers have the option of distributing the electricity with different amperages. Sometimes the car battery charger will be able to differentiate this on its own, whereas other times, you might need to know what amperage the battery requires and set the car battery charger to that amperage.

It is worth noting that the different amperages will also affect how quickly the car battery charger will charge the battery. That said, you must still be careful because there are plenty of batteries out there with a maximum amperage rating, at which point it can be dangerous to charge the battery beyond. In this instance, you can risk damaging the battery or the charger, and it is not at all unheard of that the car battery charger even begins to smoke when pushing too high of amperages.

Charge Phases

This is a feature that can greatly improve the car battery charger performance, but it is not, strictly speaking, necessary. Essentially, a car battery charger with different charge phases is able to first read the electrical signals from the battery and decode that information to determine what kind of state the battery is in. The car battery charger will then adjust its charge setting to best accommodate the state of the battery so that it responds to any potential issues.

The most common type of phase beyond simply charging that comes with car battery chargers that have multiple charging phases is the maintenance phase, which, despite its name, does not always actually provides the battery with any restorative benefits. Instead, a maintenance charging stage identifies what the idle amperage of the battery is – the amount of energy the battery inherently releases when plugged up but not powering – and keeps providing that amount to top it off without ever overcharging it.

Charge Phases

Size

Back in the day, if you wanted to charge a battery, there was a pretty good chance that the battery charger was nearly as large as the battery itself. This made it fairly difficult to keep a battery charger on hand with you. Thankfully, with today’s progression of technology, car battery chargers have been miniaturized to the point that they can often fit in the palm of your hand. However, this compact size actually presents more benefits than simple convenience.

For instance, many situations where you may need to charge a car battery do not even involve vehicles. There are numerous circumstances where a car battery may power an unrelated electronics array. In this situation, you may want to keep a maintenance car battery charger connected to it at all times. With a smaller car battery charger, this is much easier to do and makes moving the arry easier as well.

Element Proofing

Unlike the batteries that they charge, car battery chargers are not always the most protected against intrusion by the outside elements. Considering the bulk of a car battery charger is simply wires and circuit board as well as the power transformer, which actually changes the AC input electricity into DC output electricity for the battery. As such, if a car battery charger is not properly protected, it can become damaged and fail when exposed to the elements.

In this instance, your 2 biggest concerns are water and dust. Keep in mind, heat can also be a problem, but it is easily rectified by simply putting the car battery charger in a shaded area. For the water and dust, there is an IP rating system that determines how resistant to these contaminants the car battery charger is. This quality is far more important for a car battery charger that will be used to charge a battery used for a non-vehicle array of electronics.

F.A.Q. about Charging and Maintaining Car Batteries

1. How Long Does it Take to Charge a Car Battery With a Charger?

The time it takes to charge your car’s battery with a charger depends on how powerful of a charger you use. High amp chargers can charge a car’s battery relatively quickly, while low amp chargers, often called trickle chargers, will charge it slowly over a long period of time.

At the high end, a 40 amp charger can have your car battery up and running only minutes after hooking it up. At the low end, a 2 amp charger can take as much as 24 hours to charge your battery.

2. What is the Best Way to Charge a Car Battery?

When charging your car’s battery, you may need to remove it from its housing in the car. If so, you might need special tools to remove it. Otherwise, make sure all accessories and lights are off in the car before you charge it.

Make sure the charger is off, then hook the charger up to the battery with its cables. Make sure that the positive and negative cables are properly hooked to the right terminals in the battery. Now, you can turn on the charger and begin to charge the battery. Make sure to monitor the progress of the charging, and stop once your battery is charged up.

3. Can a Dead Battery Be Charged?

In most cases, a dead battery can be recharged. You may be able to get a battery running again by using jumper cables and another car’s working battery. In many cases, you’ll need a charger to get the battery running again.

Sometimes, a battery will have a dead cell. In that case, it won’t take charge even from a charger. You’ll need to replace or repair your battery if a cell is dead.

4. Can I Leave my Car Battery Charging Overnight?

You can leave your car battery charging overnight with no problems. However, make sure that the amperage you’ve set it to is low. If you’re charging at 2 amps, it may take 24 hours to charge a battery, and at 5 amps it will take around 12 hours.

In those cases, it’s fine to leave the charger on all night. But if you set the amperage too high, you risk overcharging the battery.

5. How Can I Charge my Car Battery at Home?

If you have multiple vehicles at home, you can charge your battery with jumper cables and a working car battery. This type of charging method should only be used in emergencies.

The better method for charging a battery is to use a battery charger. These devices will recharge a car battery at a variety of speeds. Owning a car battery charger can be a solid investment if it keeps you from having to buy a new battery after it loses its charge.

6. What Happens if You Leave a Car Battery Charger On Too Long?

If you leave an older-style car battery charger on for too long, you will eventually kill the battery. This was true even if you were using a trickle charger running on 2 amps. Of course, if you use a higher amperage, you’re at risk of overcharging your battery even quicker.

A substance called electrolyte is what allows your battery to be conductive. An electrolyte usually is in liquid form, but overcharging the battery causes hydrogen and oxygen to become gasses. If the battery overcharges for too long, these gasses build up within the battery and eventually cause the battery to burst.

Modern battery maintainers, such as the ones mentioned in this list, are specifically designed to protect your battery from being overcharged. They have multiple stages of charging and will moderate the voltage and current to make sure your battery is always in perfect condition.

7. How Often Should You Charge Your Car Battery?

If you drive your car regularly, there’s usually no need to charge it additionally. When the car is running, the alternator is charging the battery — presuming the alternator works correctly. Even driving your car once a week should mean you don’t need to charge it.

If the car sits for weeks or more without being driven, you may have to charge it to get it back to a proper voltage. If a car is going to sit undriven for a long period of time, charging it every month or so is a good idea.

8. How Long Does it Take a Car Battery to Recharge?

How long a car battery takes to get to fully charged state depends on three things

  1. How much it was decharged,
  2. The current of your charger (anywhere from 1.5A and avove in this list),
  3. The type of battery, and
  4. The capacity of the battery.

For example, a typical wet battery that starts a car engine will have a capacity of around 75Ah, and when that’s just half used, it will show up as being flat, and be unable to turn the car over.

That means to charge it up, you’ll need to fill it up with 32.5Ah. So if you’re running a trickle charger that charges at 1.5A, it’ll take about 24h.

There’s a further complication in that you can charge a battery up to 80-90% rather quickly, but to get it to 100% will take a bit longer. That said, you only need to use a car battery charger to take the battery to 90% in order to be able to start the engine.

In general, to rescue a flat battery, I’d recommend a charger with at least 10A of current.

9. Can You Overcharge a Car Battery With a Charger?

You absolutely can overcharge a battery while using a car charger if you have an older style charger. It’s important to set the proper amperage on your charger and know how much time it will take to charge the battery.

It’s also important to have the latest technology in chargers. Modern chargers detect the voltage of the battery and know the battery type so can respond to how fully it has been charged, and protect from over-charging.

10. Is It OK to Leave a Car Battery Charger Plugged In?

It’s perfectly fine to leave a battery charger plugged in. In fact, if you’re using a relatively low amperage charge, it’s going to take 12 to 24 hours to charge your battery. You’re probably not going to want to sit around waiting for it to charge up.

With modern trickle chargers that have automatic shut-off, it’s common practise to leave a trickle car battery charger plugged into a car or motorcycle over a winter for many months. This is not bad for the battery. On the contrary, it helps the battery live longer.

11. What Percent Should a Car Battery Be At?

A car battery at 100% charge should be in the range of 13.7 to 13.8 volts. The exact voltage can vary depending on the model of battery, but this is a safe estimate in most cases.

When a battery has dropped to around 12.4 volts, that’s about 75% capacity. At 12 volts, a battery is running at 25% capacity, and by the time it hits around 11.9 volts, it is completely discharged.

You can take a voltage reading in order to gauge your battery’s voltage level and recharge it if it’s dropped below 12.4 volts.

12. How Do You Know When Your Car Battery is About to Die?

There are a number of symptoms that can warn you that your battery is about to die. One common symptom is dim headlights, running lights, or any other lights in your car. Another is observing a clicking noise when you try to start your car.

If your battery needs to be jumped or recharged after sitting overnight, that’s another sign you might need a replacement battery in the near future. Needing to give your car gas while starting it, or a slow crank at ignition are both signs that your battery might be nearing the end of its shelf life.

13. How Can I Charge my Car Battery While Driving?

If you’re out on the road or parked remotely and have battery trouble, jumping your battery is usually your best option. If you have a pair of jumper cables and can enlist the help of another motorist, you can quickly jump your battery back to life.

For this reason, it’s always wise to carry jumper cables in your trunk. It’s easy to leave your lights on, or the car door cracked when parking somewhere, especially if you’re in a hurry. If your battery dies, it’s far better to jump it with cables than have to call an auto professional to come out and jump the battery for you.

14. How Long Should I Drive to Charge my Car Battery?

The amount of time you need to drive to charge your car’s battery depends on how long you plan to let it sit. If you’re driving at regular intervals, even driving for a couple of minutes is enough to keep your battery running just fine.

If you’re going to let the car sit for a week or more, it’s best to drive it for around 20 minutes. Driving for at least 15 minutes will give the car’s alternator time to get the battery back to a good level of charge. This should last you for at least a week, if not longer.

15. Does Charging a Car Battery Damage It?

Properly charging a car’s battery will put some minimal wear on the battery, but nothing significant. Using jumper cables and another working battery can put wear on your alternator, but that’s a separate issue. Because of the risk of alternator damage, you’re better off using a car battery charger than jumper cables to recharge a battery.

Overcharging a car battery will do damage to the battery. Leaving a charger hooked up for too long will eventually blow out the battery, leaving you needing to replace it.

16. Can Trickle Chargers Damage Battery?

There’s a misconception out there that trickle chargers can’t overcharge or damage a battery. The thinking is that the amperage is low enough that you can run it indefinitely with no problems. This is false. A trickle charger can damage a battery if it runs too long.

Any car battery charger will eventually damage a battery if it’s left on past the optimum charging point. There’s a separate type of charger called a float charger or a maintainer. This device charges your battery up to a certain point and then switches off, preventing overcharging. For example, the float trickle charger we recommend is safe to leave plugged into your battery for a long time.

17. How Many Years Does a Car Battery Last?

The standard battery has an expected lifespan of around 5 to 7 years. Keep in mind that this is only an average – Some batteries end up lasting ten years or more. Others will fail and need replacement in fewer than five years.

The way you treat your battery can have a big impact on its shelf life. If you leave your car idle and undriven for long periods of time, this can lessen a battery’s lifespan.

18. Should I Charge a New Car Battery?

There’s no need to charge brand-new car batteries. Car batteries are sold with the charge fairly close to 100% and are ready to drive with as-is.

If you’re especially worried, there’s nothing wrong with taking a voltage reading on a new battery you buy. It’s possible, though unlikely that it somehow lost charge between manufacture and sale. But this is a fairly unlikely scenario.

19. What Voltage Is Low For a Car Battery?

For most modern car batteries that aren’t lithium, there are three voltages that indicate how charged your car is:

  • 12.8 and above: Fully charged
  • Around 12.4: Around 75% full, charge it
  • 11.9 and below — flat, needs to be restored.

The point at which you can consider your car’s battery voltage as low is under 12.4 volts. 12.4 volts usually is the point where a battery is around 75% charged. Try to keep your battery above 12.4 volts if possible to keep it healthy.

That’s not to say a car won’t run if the battery is below 12.4 volts. While you may see some signs that the battery is on the verge of going dead, your battery will work below that threshold. By the time it hits 11.9 volts, your battery’s charge is dead, and it will need to be recharged before you can drive it.

20. Can You Drive a Car With a Dead Battery?

You may be able to drive a car with a dead battery for a little while, but it’s not a good idea. If your battery is dead, it’s possible that you’ll be able to start your car by jumping it off another working battery and even drive it.

But in doing so, you’re going to be putting a strain on your alternator. Eventually, you could damage the alternator and will have to pay more to get an alternator replaced than you would buy a new battery. Not to mention, you will be stranded at whatever point you turn off the engine unless you can get another jump.

21. How Do I Keep My Car Battery Charged?

The best and easiest way to keep your car battery charged is to drive your car regularly. When you drive your car, the alternator charges up the battery, unless there’s something wrong with the battery that keeps it from holding a charge.

If you can’t drive your car regularly, you can use a car battery charger to bring your charge back to ideal levels. You can also use a device like a battery maintainer to keep your charge level at 100% levels.

22. Will Car Battery Die if Not Used?

Over time, your car’s battery will die if the car isn’t used. The reason this happens is that the chemical reactions by which batteries give power continue to happen even if the battery isn’t actively being used. It happens far more slowly, but the battery continues to give out power and will eventually drain.

When you drive your car, the alternator recharges the battery, recharging any lost power over time. Keep in mind that in order to keep your battery charged, you need to drive the car. Simply leaving it to idle won’t engage the alternator and recharge the battery.

23. How Often Does a Car Battery Need to Be Replaced?

There isn’t necessarily a set time period for replacing a battery. The short answer is that you’ll need to replace the battery when it dies and can’t be recharged. But you can’t necessarily know when that’s going to happen.

As a rule of thumb, most batteries last in the five to seven-year range. If you’re planning for your budget or routine maintenance, any time after five years is a reasonable time to expect to have to replace your battery. But this isn’t set in stone. You might find that your current battery will last for years past that date.

24. How Do You Know if Your Car Needs a New Battery?

If you have a battery charger and are comfortable using it, you can recharge a battery that has lost its charge. The point at which you’ll need to replace the battery is when the battery is no longer able to hold a charge even when you recharge it using the charger.

This can often be the result of a dead cell within the battery. When this happens, unless you’ve got the expertise to open up a battery and fix it, the battery is dead. We don’t recommend trying to fix a battery in this way unless you have lots of previous experience working with batteries in this way.

25. Can You Overcharge a Car Battery?

It’s possible to overcharge a battery. Once the battery reaches its maximum recommended voltage, any additional charging will begin to wear out and damage the battery. For most batteries, 13.7 volts to 13.8 volts is 100% charged.

If you charge beyond that point, you will start to create excess gasses within the battery, which causes some problems. If you keep charging, you’ll blow the battery out and render it permanently ruined.

26. What is the Maximum Charging Voltage for a 12 Volt Battery?

While you’re charging your battery, the voltage can reach levels as high as 15 or 16 volts in the short term. This is okay, and won’t harm your battery as long as you don’t maintain those levels for more than a brief period of time.

When charging your battery, you don’t want the voltage to exceed 14.4 volts for more than 8 hours. And you don’t want the voltage to be above 13.8 volts for more than a 24 hour period. As long as you keep the voltage under those levels and time thresholds, you won’t do any damage to your battery while charging it.

Conclusion

As we can see, there is no product that will satisfy everyone as the best car battery charger due to the different types of chargers as well as the different needs of potential consumers. The charger that someone needs to charge large industrial vehicles is not at all the same kind of car battery charger someone would look for if they simply needed to recharge the battery in their own car.

For the former, we recommend the Schumacher SE-3000 with its sheer range of options. With the various voltages and amperages, there is a good chance that even though this was designed to be used as an industrial car battery charger, it can actually charge much smaller batteries. On top of that, it is by far the most durable product we reviewed.

Of course, for the average consumer, the Schumacher SE-3000 is simply more than they need and actually quite inconvenient for their purposes. In this case, we recommend the CTEK MULTI US 7002, which though it has a narrow range of use, is ideal for most consumer purposes. The various options and precautions make this a great car battery charger for your everyday vehicle.

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