Frequently Asked Questions

What is the difference between a Deep Cycle Battery and a normal Lead-Acid Car Battery?

Both car batteries and deep cycle batteries are lead-acid batteries that use exactly the same chemistry for their operation (see How Batteries Work for more information). The difference is the way that the batteries optimize their design:

A car's automotive battery is designed to provide a very large amount of current for a short period of time. This surge of current is needed to turn the engine over during starting. Once the engine starts, the alternator provides all the power that the car needs, so a car battery may go through its entire life without ever being drained more than 20% of its total capacity. Used in this way a car battery can last a number of years.

To achieve a large amount of current, a car battery uses thin plates in order to increase its surface area.

A deep cycle battery is instead designed to provide a steady amount of current over a long period of time.

A deep cycle battery can provide a surge when needed, but nothing like the surge a car battery can. A deep cycle battery is also designed to be deeply discharged over and over again (something that would ruin a car battery very quickly).

To accomplish this, a deep cycle battery uses thicker plates.

When do I need a Deep Cycle Battery?

People who have Recreational Vehicles (RVs) and boats are familiar with deep cycle batteries. These batteries are also common in golf carts and large solar power systems (the sun produces power during the day and the batteries store some of the power for use at night). If you have read the HSW article entitled How Emergency Power Systems Work, then you also know that an alternative to gasoline powered generators is an inverter powered by one or more deep cycle batteries.

What are Cold Crank Amps? (CCA)

CCA (Cold Cranking Amps) - the number of amps that the battery can produce at 0 degrees F for 30 seconds.

What is Reserve Capacity? (RC)

RC (Reserve Capacity) - the number of minutes that the battery can deliver 25 amps while keeping its voltage above 10.5 volts.

Typically a deep discharge battery will have 2 or 3 times the RC of a car battery, but will deliver one half or three quarters the CCAs. In addition, a deep cycle battery can withstand several hundred total discharge/recharge cycles, while a car battery is not designed to be totally discharged.

Activation of a Dry Battery

Special order batteries may be shipped dry (acid shipped separately). To activate these batteries, start by removing the vent caps. Using approved battery grade electrolyte (1.265), fill each cell half way between the plates and the bottom of the vent well tube. (See Figure 4 on page 5) It is important not to over fill the cells as the acid will expand upon charging. If the cells are too full, the acid will spill out of the top of the cells. Allow electrolyte to saturate into the plates and separators for at least 90 minutes. The temperature of the electrolyte will rise and the specific gravity will drop. Once this is complete, place the batteries on charge at the finishing rate (5% of the 8 or 20 hour rate). The rate may be increased if the battery does not begin to gas. Do not let the cell temperature exceed 115° F (46° C). If the temperature becomes excessive or the cells begin to gas vigorously, reduce the rate of charge. Continue charging until the cell (or cells) reaches within .005 points of the specific gravity of the filling electrolyte corrected for 77° F (25° C).

We recommend to continue charging for an additional 60 minutes to insure no further rise in specific gravity.

Top up or remove electrolyte as necessary for proper level. Never add electrolyte (only approved water) after activation. Replace vent caps and remove any spillage of electrolyte. If necessary, clean with bicarbonate of soda and water (100 grams of soda to one liter of water). Rinse with water and wipe dry. Ensure that soda solution does not get into cells.

*Do not place on charge until electrolyte temperature is below 35°C.

For detailed information on Battery Activation, please refer to Technical Support Troubleshooting

What is Equalization?

Individual cells will vary slightly in specific gravity after a charging cycle. Equalization or a “controlled overcharge” is required to bring each battery plate to a fully charged condition. This will reduce stratification and sulfating, two circumstances that shorten battery life. Equalization of the battery bank is recommended every 60 to 180 days, depending on the usage of the individual system. To equalize the cells, charge the batteries until the voltage elevates to the “Equalization” voltage shown in Table 2. Charge parameters and maintain for 2 to 3 hours per bank. A constant SG for 30 minutes is a good indication of cell equalization. It is recommended to water the battery cells half way through the equalization. This will assure the water is mixed with the electrolyte.

Cleaning

Batteries should be kept clean at all times. If stored in a dirty area, regular cleaning should be performed. Before doing so, assure that all the vent caps are tightly fastened. Using a solution of water and baking soda (100g per liter), gently wipe the battery and terminals with a damp sponge, then rinse with water.