Battery Voltage Monitor

Battery failure is the most common reason for emergency call outs to roadside breakdowns. It is an inconvenient and expensive problem but it need not happen with a battery voltage monitor installed. These devices provide an accurate indication of the charge level, and some can even predict when a battery will fail. There are even monitors that disconnect electrical accessories when the voltage drops below a certain level, leaving just enough power to start the engine and charge the battery again. There are several types of battery voltage monitor so choosing which one to buy depends mostly on the level of protection required.

There are many good reasons for installing a battery voltage monitor. They give a better indication of the charge level and they help avoid deep discharging, which can shortens battery life. The battery warning light found in most cars does not indicate the voltage or charge state, and is small enough to go unnoticed. Even when drivers do notice the light, many are confused by what it means exactly. The light usually appears when the alternator is not providing enough voltage to charge the battery, meaning that the it will soon run flat. Almost all car batteries are the lead-acid type which can be damaged if they are used when they are almost flat. This is called deep discharging, and it causes irreversible changes to the battery that limit its ability to store energy.

The battery voltage monitor is an aftermarket product available at most automotive parts stores, and is also sold in kit form at some electronics stores. It consist of a display unit that is mounted on the dashboard and leads for connecting it to the battery. The connection can be made using the cigarette lighter socket, sometimes called the accessories socket, or by inserting a special plug into the fuse board. The leads can also be connected directly to the battery terminals with alligator clips, or to any other part of the electrical system that gets its power from the battery. The voltage level is displayed as numeric value in the case of LCD displays, or as one of several colored LED lights that represent certain charge levels.

Voltage is a good indication of the charge state but it does show the overall condition of the battery. A battery can show a full charge voltage but not be able to provide the huge loads required to start the engine. That's where another type of battery voltage monitor comes in useful. It can roughly predict when a battery will fail by measuring the voltage drop as the engine is started. The display shows the percentage of battery life remaining, along with the current voltage level. These monitors need to be connected directly to the battery and are usually mounted between the terminals.

There are many automotive electrical accessories, such as DVD players and GPS navigation units, that are powered by the car battery. They add up to a significant power drain that can quickly drain the battery. Another type of battery voltage monitor is available that disconnects these accessories before that happens. They are connected between the accessories and the power socket, and continuously checks the voltage level. When it drops below a certain level, the monitor cuts off power to the accessories.

Whether a battery voltage monitor actively protects the battery or just displays the voltage, it is better than relying on the small and vague warning light found in most cars. Automotive batteries are expensive to replace, and having one go flat is a major inconvenience. These monitors are a compact and inexpensive way of avoid that problem and extending the life of the battery. They can even give motorists the leisure of choosing when to buy a new battery, rather than being forced to accept the often inflated price of emergency batteries.



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  1. Cigarette lighter battery/alternator monitors don't really do anything to actually protect your battery or keep it from going dead, but if you have an older vehicle their a godsend because they do let you know when you're having a battery/alternator problem by constantly monitoring the battery and charging system voltage.

    You can find a good cheap one at http://www.battery-genius.com