Choosing a battery charger for your car, boat, or RV can be confusing process. There are so many choices out there that how is one to choose? Over the past several years we have purchased several different types and some have worked out and others haven’t. We’ve learned quite a bit along the way and hopefully this article will help you avoid some of the mistakes that we’ve made.
I really think that everyone should have a charger at their home or in their shop. Even if you aren’t mechanically inclined, you should own one. They are simple to use and they can really be a life saver when you go out to start your car and realize that you left your lights on from the night before.
In it’s most simple form, a battery charger is a device that takes household electricity which is at 120 volts AC (alternating current) and converts it to 12 volts DC (direct current) which is what your vehicle’s battery needs.
When you connect the charger clamps to your battery, 12 volt electricity flows into it thereby charging it up. They actually put in more than 12 volts but most people are familiar with the term 12 volt battery and that’s why I use it. Most chargers actually produce around 14.6 volts or more while charging.
Most chargers have several settings. The most basic of which is the voltage setting. Some specialized applications use 6 volt batteries but most vehicles have 12 volt systems. It’s kind of rare to see a 6 volt battery in use these days. Even so, some chargers have the ability to select between 6 or 12 volt charging settings.
The second setting is “amperage”. Amperage is the amount of electrical energy flowing through the wires at any given time. The settings for amperage vary greatly from charger to charger. You can think of it like this. If you set the charger on a low amperage setting like two amps, the battery will charge very slowly. This is known as a “trickle charge”. If you turn the amperage up to say 40 amps, the charge will complete much faster. Some chargers even have a 100 or more amp setting for jump starting your vehicle.
More Power Is Not Always Better
It’s important to note that not all batteries should be charged at a high amperage setting. Small batteries such as those found on motorcycles should be charged at only two to four amps. Larger automotive batteries should be charged at around 10 to 20 amps. While turning the amperage up during the charging process will complete the charge faster, it’s generally not healthy for the battery to charge it too fast. If you have the time, charging it on a lower setting is usually better for the battery.
Some people may wonder why they would need a battery charger if they already have jumper cables. We’ve all had mornings when we go out to our car and it won’t start so we search out a friend or friendly stranger who is willing to give us a jump start. It’s true that you can usually get your vehicle started this way but you should still charge your battery with a proper charger as soon as possible.
It can be very hard on your vehicles alternator to charge a deeply discharged battery. Alternators are designed for light recharging of batteries after the vehicle has been started. They are not designed to constantly charge batteries from a very low charge state to a fully charged state. Too much of this will permanently damage them.
There are a few types of chargers to choose from. The first is the fully manual style. With this type of charger, you manually control the entire charging process. You select the charging voltage as well as the charging current. There aren’t any voltage sensors or timers on this type. I would NOT recommend this type of charger. It’s way too easy to over charge your battery and seriously damage both the battery and your vehicle should the acid boil out and spill onto your engine compartment.
You CAN charge your battery with this type of charger BUT the voltage of the battery must be constantly monitored until it reaches its full charge. A fully charged battery in good condition will actually show around 12.6 volts when connected to a multi-meter.
This type of charger is certainly better than the first. You still have manual control over the voltage and amperage settings but the rest is automatic. When an automatic charger is connected to a battery, the internal meter in the charger will closely monitor the state of charge. When the battery voltage reaches 12.6 volts, it will automatically shut itself off. This will provide for a full charge and prevent the charger from damaging your battery.
There are many inexpensive automatic chargers available to choose from. This charger will do a decent job of charging your batteries but it’s still not the best.
This type of charger commonly has a “vehicle starting” setting. You set the charger to “start” and wait a few minutes for your battery to get a boost. During this time, the charger is dumping a large amount of current into the battery to bring it up to a state that might allow you to start your vehicle. This is similar to jump starting your vehicle.
The third type of chargers are called “smart chargers” or “three stage chargers”. This is the latest generation of battery chargers and they are much more advanced that the first two types.
With this type you still have control over the voltage and amperage settings but the rest is automatic. When you first connect these chargers to your battery and plug them in some interesting things happen. First, the charger accurately measures the current voltage of the battery. Second, it attempts to analyze the condition of the battery. Should there be a problem with the connections or the battery itself, the charger will show you a code to let you know what it thinks the problem is. It will tell you something like the battery has an internal short or the battery is heavily sulfated.
In some cases these chargers have the option of trying to fix the problem. Batteries that have been abused or neglected often have chemical deposits in them. This is called sulfation. Many of the smart chargers have a setting called, “recondition” or “desulfate”. When the charger is in this setting, it will deliver a series of high voltage pulses to attempt to dissolve the sulfation and restore the battery to good health.
Another problem that occurs as batteries age is when the internal cells charge and discharge at a different rate from each other. Twelve volt batteries consist of 6 – 2.1 volt cells. Under certain circumstances, one or more of these cells will be at different voltages than the others. Some smart chargers have the ability to “equalize” all of the cell’s and return the battery to a healthy state.
Three Stage Smart Charging
When a smart charger begins the charging cycle it will be in the “bulk” phase. During this phase, the maximum amount of amperage that you have selected will be pumped into the battery. The second phase is called “absorption”. In this phase the charger will periodically let the battery rest and absorb the charge. It then reads the voltage of the battery and cycles the charger into “bulk” again should the battery require more charging.
The third phase is called “float”. In this phase the charger will go into a low trickle charge mode in which it will restrict the current to zero or near zero amps.
Your batteries will love you for charging them with this type of charger. Not only do they typically charge faster than the other types of chargers but they will help increase the lifespan of the battery.
Did You Know That You Can Jump Start Your Vehicle With a Battery Charger?
Most modern chargers have a “start” function. This is a great alternative to jump starting your vehicle because you won’t have to search out a friend or willing stranger who has jumper cables. You simple hook up the charger to your battery, plug it in, set it to start, wait a few moments, and turn the key. It’s very easy and convenient and it you never use your charger for anything but this, it will have paid for itself!
How To Connect The Charger To Your Vehicle
A lot of people are intimidated by the thought of connecting a charger to a battery. They really shouldn’t be because it’s actually quite simple. You should always follow the instructions that come with your particular charger but here are the basic procedures that apply to most chargers. Note: These instructions are for negatively grounded vehicles only.
- Open your hood and find the battery.
- Examine your battery. There are two posts with large cables connected to them. One wire will be “positive”. This post will have a “+” sign by it. The wire that is connected to this post will be red. The other post will be “negative”. It will have a “-” sign near it and a black wire attached to it. You should never attach the battery cables directly to the negative post!
- Connect the black (negative) clamp on your charger to something that is solid metal inside your engine compartment. This should not be near your battery, the fuel lines, carburetor, or fuel injectors.
- Connect the red (positive) clamp on the charger to the positive post on your battery.
- Plug the charger in.
- You’ll often have to use an extension cord for this.
- Turn the charger on and select the appropriate settings.
- Wait for the battery to charge. If you have a manual charger, you must stay with the charger and frequently check the voltage of the battery with a suitable meter. If you have an automatic charger or an automatic smart charger, go about your business and check on it later.
- When the battery is fully charged, unplug the charger.
- Remove the red (positive) clamp from the battery.
- Remove the black (negative) clamp from the metal part that you fastened it to before.
- Enjoy your charged battery!
Important Safety Precautions
Batteries contain corrosive acid that may burn you. You should always wear gloves and eye protection while working on or around batteries.
When batteries are charging they undergo a chemical reaction. During this time, highly combustible hydrogen gas is released. You should only charge your battery in a well ventilated area and you should never charge your battery near an open flame as the hydrogen gas could possible ignite and explode.
Some people simply attach the red clamp to the positive battery post and the black clamp the the negative post. This is a bad practice to get into because like I mentioned before, as the battery is charging, hydrogen gas is released. If the battery clamps arc and cause a spark while removing them from the battery, any accumulated hydrogen could explode. That is why you should follow the above procedures. It is also why you should unplug the charger before removing the clamps. If the charger is unplugged, there shouldn’t be any arcing or sparks when you remove the clamps.