LOADING AND LIFE CYCLE OF BATTERIES

Proper loading of a battery is key to prolonging its life. Unfortunately most people do not understand what constitutes proper loading. To compound the problem most boats are not equipped with the necessary instruments so that the owner can measure and monitor how the Sony VGP-BPS14 battery is used and loaded.

Smart loads have built in protection circuits that shut down if the battery voltage drops below a certain threshold.

Unfortunately, many loads such as lamps, blowers and bilge pumps simply keep
draining the battery right down until the terminal voltage reads zero. Such excessive discharges creates permanent damage inside the battery. Flooded wet cells are especially prone but even gel and AGM batteries can be damaged.

Sometimes, it is more important to keep the load running than to disconnect the
battery. If the boat is flooding, it is more important to keep the pumps going that worrying about the long-term damage to the battery.

However, more often it is a case of a forgotten light somewhere that is left on and totally drains the battery while the boat is unattended. Having a charger connected while docked prevents this, but at the risk of over charging the battery if the charger is not a “smart” charger.

What is really needed is some sort of battery monitoring system that tracks all usage and stores that historical data for later analysis. You can buy such a device. Marketed under a variety of names; e-meter, battery gauge, Link and such, these are really small micro processors that accurately measure how much energy is drawn from or fed into the VGP-BPS14 battery bank, how deeply the battery was discharged and how often the battery was cycled.

Unfortunately, there still isn’t anything on the market that will notice a forgotten light and turn it off in your absence. Human intervention is still required.

The length of service life a battery has is directly related to how deeply it is discharged. If you only deplete a battery by 30% before completely recharging it you will see much more than a tripling of expected service life.

The rate of discharge will also affect how well the battery stands up. If you have very large peak loads that are used frequently, you need a larger capacity battery than if the loading is light and steady at a much lower rate.

This is still valid even if the total amount of energy (amp -hours) consumed is the same. With the proliferation of inverters on board this effect is becoming more noticed than in the past.

Bow thrusters, and anchor winches also represent large peak current loads that alter the service life of a battery bank.

Inverters are perhaps the most common device being brought aboard boats. These devices allow you to use household appliances on board even when you do not have a genset or connected to shore power. Unfortunately, they place huge strains on a battery. The ratio of 12 volts to 120 volts is mirrored in the current. If you use 10 amps at 120 volts then you will need 100 amps at 12 volts. That means a micro wave oven, toaster oven or hair dryer places a load of anywhere from 80 to 150 AMPS load on the battery for Sony VGP-BPS14 as long as it is turned on. Only large deep cycle batteries can stand up to that sort of service. Ordinary starting batteries will turn to mush after a short period of time.

From the above it should now be obvious that to prolong the life of your battery, you need to keep track of how much energy you draw from the HP EliteBook 6930p battery, how fast you draw that energy and finally how and when you replenish that energy by recharging. If you only have a simple system on board with perhaps a single Group 29 or Group 31 battery then all you really need is a voltmeter and amp meter in the electrical panel. You need to keep manual track in your mind or how much power you use and for how long. If you have flooded cells then you need to check the fluid level monthly and measure the specific gravity to guard against sulfation building up. If you opt for the “maintenance free” sealed types, and then you need more sophisticated means for measuring what is going on. The various models of e-meters, Links or whatever is the best way to do this. These devices will provide you with the necessary information needed to plan your charging strategy.