Auto Battery Charger

Charging your car's battery should be straightforward, but there are a few things that you need to consider before you begin. Some of this stuff might seem overkill, and preparing for the least likely situation, but taking these precautions before charging your car's battery is required if you're going to protect both yourself and your battery.

Before You Charge:

• Read the instructions included with your charger.
• Locate the battery somewhere that's well ventilated.
• Remove the vent caps of batteries that have them, and check the water level inside. If it's low, you'll need to add distilled water until it covers the top of the plates. Make sure that you don't overfill the battery.
• If you've removed the vent caps, be sure that you replace them.
• Use protective gear, such as eye covering, rubber gloves and work clothes. It's also good to make sure that you remove and jewelry, such as your wedding band or watch.
• Be sure that your battery isn't frozen. You don't want to attempt to charge a frozen battery. Make sure that the temperature is 60 degrees Fahrenheit or greater before you try to charge your battery.
• Test with a hydrometer to determine the specific gravity, or check the battery with a voltmeter to determine its state of charge. There's no reason to try to charge a battery that's full & you can do harm by doing so.
• Connect the leads of the charger to your battery before you plug the charging unit into. If your battery has side posts, or is studded, you want to use the proper adapter for these connections. This ensures that the proper contact is made and there's no risk of fire.
• Set your charger to the proper settings for your battery. This is key to ensure that you don't damage the battery during charge. You'll need to find out what the settings should be before you set the charger up and plug it in. (Common settings include: 6 volts, 12 volts, low-maintenance, sealed, standard automotive, deep marine).
• Select the lowest setting for the amperage on your charger. After you've begun to charge, you can increase the amperage, but to begin you want to keep it as low as possible in case something goes wrong.
• Plug in the charger and turn it on.

While Charging Your Battery

• Don't touch the connections. You don't need to wiggle them to make sure that they are a snug fit, this should have been done when you first connected them & you run the risk of shocking yourself if you interfere with them.
• Keep the vent caps on. You don't need to check the level after you've corrected it in the pre-charge process, so you shouldn't be removing the vent caps for any reason.
• Don't smoke or use any open flames around the battery.
• Check the temperature regularly during charge. It's okay to come back and touch the housing of the battery during charge, just not the poles or connectors. If the battery becomes hot to the touch, you need to stop the process and make sure that you've done everything correctly. This is a sign of resistance and can cause a fire or worse. Turn off the charger first, unplug it, then remove the connectors to the battery. If this is a problem for you, you may want to clean the terminals. If that doesn't solve your problem, it's best that you have your battery tested for usability.

After The Charge

• Turn off the charger & unplug the unit. Overcharging will lessen the lifespan of your battery & lead to failure.
• Disconnect the leads from the battery terminals. You want to make sure that the unit's off first, then disconnect the leads to ensure that no charge is coming in or going out of the battery.

Keeping your battery fully charged will ensure that you aren't left stranded when you need your vehicle.  For this reason, many people purchase a battery charger for use at their home.  This is practical maintenance and something that will save you a headache later down the road.

There are many different types of batteries that are use in automobiles today.  Having the correct type of charger is important, as you can damage your battery if you don't use the right charger.  Most charging units allow you to change the settings so that you can select from a variety of battery types, to ensure that you don't cause damage or run into problems.

Deep cycle batteries, for example, generally do not require any special type of charger, but there are certain settings that you want to ensure that you get right before a charge.  In specific, you want to make sure that your deep cycle is charged at a slow rate.  Many chargers will have a setting for deep cycle batteries, however if you already have a charger that doesn't allow you to choose this, then you're going to want to make sure that the maximum current coming from the charger (amp) is less that 20% of the Ah rating of your battery.  If your rating is 100 Ah, then 20 amps is the max for your charger.  If you go over this, you run the risk of damaging the battery.

Also, the length of time that is required to complete the process is a concern.  For the type above, you're going to want to make sure that the process can be completed in about 10-12 hours.  For a normal automotive battery, you can generally charge the battery with in about 6-10 hours using a 10 amp charger.  The atmospheric temperature will have an impact on the total time spent, but in general those settings should be accurate for most charges.

Of course, if you're unsure about how long you need to leave the battery on the charger, then you should refer to the instructions that were included with your charger.  You should be able to look at the booklet and determine time by referencing the type of battery.  Be sure that you're careful & ensure that you don't need to cross reference amperage as well, as there are some units that ship a standard instruction booklet for a series & may have different amperage models to choose from within the same book.  If you're allowed to change the current on your charger, which you most often are, then you want to make sure that you set this for the lowest amperage that your battery will accept.  If you start charging your battery and find that there is heat buildup, then your battery is not accepting the current and you're running the risk of fire by leaving it on the charger like this.

It's important that you not undercharge your battery, as this will cause sulfation and premature failure of the unit.  You must also be sure that you haven't overcharged the batter.  This causes corrosion of the plates within the battery, as well as consumption of the water within the battery.  For sealed units, this will mean that you'll have to purchase a new battery prematurely.

Following this quick guide will help you ensure that you get the proper charge on your battery, and that you aren't left stranded when you need the battery the most.  You should always check the battery's charge with a voltmeter.  Also, if your charger has a swing needle, you should reference that to ensure that the battery is in fact accepting a charge.

Common misconceptions about auto batteries.

 - Leaving them on a concrete floor will discharge them

This was a problem in the past.  The cases of many batteries were porous, sometimes made from wood, and leaving them on a concrete floor would indeed increase the discharge rate.  With advancements in the manufacture of batteries, this is no longer a concern.

 - Your car will keep your battery fully charged.

While your car does return a current to the battery, and ensures that it retains a charge, there are a lot of factors that go into how much current the battery will actually recieve.  Depending on the requirements of the alternator, your battery may not return to a fully charged state.  Also, temperature and duration of charge are factors that need to be kept in mind.  Stop and go driving, extended idling during traffic & short trips will prevent the alternator from giving a full charge.

 - Batteries can't explode

There are two types of battery explosions: internal and external.  While the causes are varied, the most common cause of external explosions is the removal of the charger.  Wet lead-acid batteries produce hydrogen and oxygen gasses during the charging process.  The vent caps ar designed to prevent this accident from happening, but occasionally sparks are caused when removing the connectors from the battery & an external explosion can occur.

Internal explosions are often the result of low electrolyte levels in the battery.  It's not uncommon for liquid to be spilled from the battery, for various reasons, and this low level causes what's known as "treeing", which can ignite the battery and cause an internal explosion.

 - Batteries Don't Lose Charge When Stored

Batteries have a tendancy to discharge naturally.  This is accelerated by the ambient temperature, but it's not uncommmon to lose up to 25% of the charge within a month's time of storage.

 - "Maintenance Free" Batteries are Maintenance Free

This is not the case.  In fact, in hotter climates, it's impossible to produce a maintenance free battery.  Due to the temperature, the battery has a tendancy to discharge and will require maintenance.

 - You Can Test Your Alternator By Disconnecting the Battery When The Car Is Running

This used to be common practice, and was safe on cars with less sophisticated electronics.  In today's vehicles, disconnecting the battery while the car is running will cause a rise in the voltage within the electrical system and will damage sensetive systems.  Because of this, it's not advised that you disconnect the battery while the car is running.

 - Batteries Last Longer in Hot Climates

The exact opposite is true.  In hot climates, a car's battery is more likely to sulfate and lose charge than in a cold climate.

 - Larger Capacity Batteries Can Damage Your Car

This is not true, because your starter motor is only going to draw a certain amount of current from the battery.  Because of this, having a battery with a larger capacity than is needed is overkill, but won't damage your car.

 - Batteries cannot change polarity

When the battery becomes fully discharged, it's possible to change it's polarity by continuing to apply load to the battery.  This can be reversed by discharging the battery fully and recharging it with the correct polarity.