Car Battery Charger: Charger Mysteries Revealed

There are many types of car battery chargers so it’s important that you know what to look for and can separate features you need from those that you don’t need in a car battery charger.  The difference can save you a lot of money and eliminate features which usually equates to extra size and weight you don’t want to have to carry around.

schumacher ssc1000aLet’s look first at some of the most common specifications of car battery chargers that are available today.  Why would you want one in the first place?  The most obvious answer is that you have a dead battery and you need to charge it back to full charge.  Not so obvious is that you may live in a cold climate and you need to keep your battery hooked up to a trickle charger to prevent it from dying when you need it most.  Even less obvious might be that you’re not sure what the problem is with your battery and you would like the battery charger to tell you if it’s even rechargeable or you might need to replace your battery.   What if your battery dies and you need to jump start your car so that you can make it home?  Some car battery chargers can actually start your car when your battery is too weak to do the job.  Some even come with an air compressor to inflate flat tires on the road.  Battery chargers can perform all these functions and more but, you might not need all the features and knowing what you need can save you time and money.

It is also important to compare specifications because these will tell you if a particular charger is up to the task you want it to perform.  It’s hard to compare if you don’t know what the specifications mean or why you would want any particular features.  Below I have laid out the most common specifications with an explanation of each and then the most common features also with explanation for each so you can compare apples to apples.

Car Battery Charger Common Specifications:

car battery charger common specifications

Car Battery Charger Type:

Not all battery chargers can charge all battery types.  Common battery types include lead acid, flooded or sealed maintenance free (very common now), in either AGM (Asbsorbed Glass Mat separators) or Gel cel batteries.  Pay attention to what type of battery or batteries you will be charging and select the appropriate unit.

battery charger tester for cars

Peak Amperes:

Most battery chargers come with this specification.  Peak amperes is the measurement of the highest peak of current draw over one millisecond or over one one thousandth of a second.  The higher the peak amperes, the more current can be drawn by the car battery charger without damaging it.  So it is usually a measurement of the quality of the components rather than a measurement of charging capability.

 

battery charging time

Average Charge Time:

Chargers can vary greatly in the average time it takes to charge your vehicle although the most common chargers anywhere from 2 to 10 hours to charge.  The faster the charge capability usually the more expensive the charger.
Portability:  This depends on the use.  If you’re going to leave it in your garage and not take it in the car, then portability is not as much of a factor.  The less portable models can be less expensive but, may have more features and will probably be larger and weigh more.  If you plan to take the charger with you which is common, particularly if the charger has a jump start feature, then size and weight become a consideration unless you have a large SUV or something like it with plenty of storage room.

car battery charger ease of use

Ease of use:

This is a very personal specification because one person’s “ease of use” is another person’s “difficult to use!”  If you’re a professional and you’re going to use the unit often then ease of use will not be as much of a factor.  If you’re a novice or someplace in between, with possibly only a quarterly use of less, then the easier the better and there are some things you should look for.  Does the car battery charger come with a good instruction manual that discusses both the proper use and safety considerations?  Does it have an automatic shutoff or go into a safer trickle charge (or battery tender) mode after charging is complete?  Are the controls simple to understand?



Does it give the user enough information via a display or lights for the user to always know the status of the charger?  All chargers have cables for you to hook to the positive and negative terminals of the battery.  Does the charger have a place to store the cables and how long are the cables.  Short cables will mean that you have to place the battery charger very close to the battery or even remove the battery to use it safely.  Longer cables will give you flexibility in where you locate the battery charger during the charging period or during “jump starting.”

jump start amperage

Jump Start Amperage:

It can require as little as 75 amps or as much as several hundred amps to start your car depending on the weather and your type of vehicle (car, truck, RV, motorcycle, etc.).  If you think you might want to charge a wider variety of vehicles or you live in a very cold weather climate, you are better off with a higher battery charger  jump start amperage.

 

Common Features:

battery charger reverse polarity warning sign

Reverse Polarity Warning:

Have you hooked up the cables correctly? A reverse polarity warning will tell you if you have hooked the positive cable to the negative post on the battery incorrectly or vice versa.

battery charger compatibility

Charger Compatibility:

As we discussed in the specifications, not all battery chargers are compatible with all battery types.  But there is also the consideration of vehicle type which can dictate a special battery which might not even be 12 volts.  Motorcycle batteries are smaller with less capacity and so don’t need the same charger performance as the larger 12 volt battery in your car.  You should check and make sure the car battery charger you are considering can handle your vehicle’s battery.  Some examples of differences in vehicle types that can affect your selection of a battery charger include car, boat, RV (recreational  vehicles), and motorcycle.

clore jnc600 car battery jump starter

Engine Start Option:

In addition to charging your car battery, some car chargers have the ability to “jump start” a car with a weak battery.  These are portable devices with a built-in battery with the “jump starting” amps to start the car.  You basically are carrying a second battery with you in case your car’s battery goes dead.

 

Fast and Slow Charge Rate:

Many chargers come with both a Slow Charge Rate and a Fast Charge Rate.  If possible it’s better to charge your battery with the slow charge rate because it’s safer and puts less stress on the battery which can make it last longer however, it will take longer (usually overnight) to charge the battery.  So when considering a particular unit remember that you will probably be using the slow charge rate but, it’s nice to have the Fast Charge Rate for emergencies.

car battery tester

Battery Tester:

Many chargers come with an indicator that can tell you what percentage of charge is left in the battery.  In addition the charge percentage, it can tell you if the problem is actually with the battery or not.  If your car won’t start but, the battery looks okay, the problem is probably elsewhere on the car.  It’s also possible to detect a bad battery in some cases when normal charging does not fully charge the battery.

fully automatic microprocessor control

Automatic Charging:

A battery charger designed for car batteries can be operated manually or automatically depending on its capability.  Manual chargers are less and less popular and require the user to track the charging process manually and stop charging when the process is complete.  This can be dangerous if you forget and the charger does not have the ability to stop charging automatically or switch to a battery tender mode automatically.  Most modern chargers have some type of automatic mode that will stop the charging process automatically when it’s complete and/or switch the charger to a battery tender mode if it has that capability.  It’s best to choose an automatic charger whenever possible.

insulated battery alligator clamps

Insulated Clamps:

Most all battery chargers now come with insulated clamps to prevent accidental shock.  For safety reasons, you should always choose a unit with insulated clamps.

spark resistant alligator clamps

Spark Resistant Clamps:

Many car battery chargers now come equipped with spark resistant clamps.  One way that this is handled is through a power shutoff that automatically shuts off power to the clamps if they are dislodged from the terminals.  This can prevent spark between the clamp and the terminal.  The reason they are not spark proof is because moving the clamps on the terminals can cause a spark even if they are not dislodged so you still have to be very careful when using them.  Another way that this can be handled is by using a spark resistant on/off switch on the battery charger that turns off power to the clamps until you’re ready to start charging.

car alternator tester

Alternator Tester:

Some chargers are now equipped with built-in alternator testers that can display either alternator voltage or an estimate of the alternator’s output as compared to “normal” readings.

Warranty:

Warranties vary greatly by manufacturer and the type of car battery charger andcar battery charger warranty are usually classified as “Limited Warranties.”  Typical warranties run between 90 days up to 5 years.  All other things being equal, a longer warranty may tip the balance in favor of one charger over another.

 

Car Battery Charger Comparison

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I would love to get your opinion of this article or hear your battery charger story.  Please take a moment to leave a comment below.

I hope this article has been helpful in preparing you for comparing car battery chargers.   For a comparison of popular battery chargers, please see our article Car Battery Chargers Top 10 Under $100.  I think you can see that there is a lot more to the selection of a car battery charger than just price.