Types of batteries
Batteries handle two basic kinds of tasks, starting an engine and running electrical loads like lights, electronics and accessories for longer time periods. To choose a battery, first determine the battery’s application and then choose from one of the three battery chemistries: Flooded, Gel, AGM.
Starting batteries, which crank the starter of your engine, are the sprinters of your electrical system. They deliver between 75 and 400 amperes or more for 5-
Starting batteries have thinner and more numerous plates, providing extra surface area to generate high amperage bursts of current. The two drawbacks of this construction are that the plates are relatively fragile in high-
Deep cycle batteries
A battery bank uses deep cycle batteries, the marathon runners of the storage system. They power the electrical loads when no charge source (land power charger, engine alternator, wind generator or solar panel) is available. Consider them a kind of savings account into which energy is deposited or withdrawn.
Compared to starting batteries which deliver high bursts of energy for short periods, deep cycle batteries make possible the delivery of amp hours over an extended period of time. Deep cycle batteries recover fully after being heavily discharged over longer periods because their design features thicker plates with a high content of antimony. Overnight, their use might deplete 10-
We generally advise that you choose either a deep cycle or starting battery for best performance and battery life, but dual-
Batteries are available in three chemical types for different applications: flooded, gel, AGM (Absorbed Glass Mat). Which type you choose is based on your needs (deep cycle vs. starting), the capacity and lifespan you are looking for and your budget.
Flooded batteries, unlike other types, use a reservoir of liquid sulfuric acid, and produce hydrogen and oxygen when the battery is being charged. Vented wet cells allow the gases to escape into the atmosphere, unlike gel and AGM batteries, which recombine the gases and re-
Flooded batteries require maintenance—periodic inspection and topping-
What to look for
Starting functions: the amount of power available for cranking a starter is measured several ways.
CCA vs. MCA:
The two common power measurements are CCA (Cold Cranking Amps, the number of amps a battery can deliver for 30 seconds at 0°F while maintaining its voltage above 7.2 volts) and MCA (Marine Cranking Amps, similar but measured at 32°F instead of 0°F). The reason that MCA are 20-
Reserve Minutes indicate how long a battery can sustain a load of 25 amps before it drops to 10.5 volts. A battery rated at 150 minutes can operate a 25A load for 2 1/2 hours (at 80°F). Starting batteries aren’t used to handle loads for long periods, so reserve minutes are less critical.
Engine size, type, and ambient temperature determine what size cranking battery you need. High cranking power (and a larger battery) is required for cold temperatures, diesel engines, or large and high compression gas engines. The first sizing criteria is to meet the minimum CCA (if any) stated by the engine manufacturer. If a Group 31, 1000 CCA battery worked well for five years, we’d recommend replacing it with a similar model. If, however, it cranked too slowly, or failed after a season or two, we’d suggest that you look for a battery with a higher CCA or MCA rating.
Deep cycle functions
Battery capacity measurements are commonly expressed in Amp-
Battery manufacturers measure longevity by discharging full batteries at a temperature of 77°F until their voltage drops to 10.5 volts. The batteries are recharged under controlled conditions, and the process is repeated until the battery fails to hold half of its rated capacity. This measurement, called cycle life, shows how many discharge cycles a battery provides over its lifespan. This ability to cycle repeatedly is what differentiates deep cycle batteries from starting batteries, which can’t withstand more than a few deep discharges before they begin to fail. If nothing else, cycle life provides a baseline for comparing one battery to another.
Battery tips for best performance
No matter what kind of battery chemistry you choose, follow these recommendations to get the best performance:
- Keep in mind that whatever ampere hours are taken out of the battery , that same number of ampere hours PLUS 20% needs to be replaced in order to fully charge the battery.
- Stay with one battery chemistry (flooded, gel or AGM) Each battery type requires specific charging voltages. Mixing battery types can result in under-
or over- charging. This may mean replacing all batteries at the same time.
- Regulate charge voltages based on battery temperature and acceptance (manually or with sensing) to maximize battery life and reduce charge time. Ensure that your charging system is capable of delivering sufficient amperage to charge battery banks efficiently. This generally means an alternator with 25% to 40% as many amperes as the capacity of your entire battery bank.
- Keep batteries clean, cool and dry.
- Check terminal connectors regularly to avoid loss of conductivity.
- Add distilled water to flooded lead acid batteries when needed. Keep them charged. Leaving them in a discharged state for any length of time will damage them and lower their capacity.
- Clean corrosion with a paste of baking soda and water.