Do you have the correct Marine battery for your boat?

                                 Do you have the correct Marine battery for your boat?


General Battery Types

Batteries are separated in two ways, by purpose and production. The foremost uses are automotive, marine, and deep-cycle. The deep-cycle will include a solar electric (PV), backup power, traction, and this is also seen in recreational vehicle use and boat "house" batteries. The major construction types are flooded (wet), gelled, and AGM (Absorbed Glass Mat). The AGM batteries are also referred to as "a starving electrolyte" or "dry as a bone", for the reason that the fiberglass mat is only 95% saturated with Sulfuric acid and there is no surplus fluid at that point.   

Starting Batteries

When we think of starting batteries are normally used to start and run engines. Engine starters require a very large amount of starting current for a very short moment in time. Starting batteries have a huge quantity of thin plates for the highest surface area. The plates are collected of a Lead "sponge", comparable in appearance to a very fine foam sponge. This gives a very large surface area, but if deep cycled, this sponge will quickly be consumed and decrease to the bottom of the cells. An automotive battery will usually stop working after 30-150 deep cycles if it is deep cycled. However, they may last for thousands of cycles in normal starting use in a 2% to 5% discharge.

Deep-Cycle Batteries

Deep cycle batteries are designed to be discharged down as much as 80% time after time, and have much thicker plates. The most important difference between a true deep cycle battery and others is that the plates are solid lead plates and not sponge. This gives less surface area, thus less "immediate" power like starting batteries need. Although these can be cycled down to 15% charge, the best duration vs expenditure method is to keep the average cycle at about 60% discharge.



Marine batteries are usually a "hybrid", and descend between the starting and deep-cycle batteries. In the hybrid, the plates may be composed of lead sponge, but it is coarser and heavier than that used in starting batteries. It is often hard to tell what you are getting in a "marine" battery, but most are a hybrid. Starting batteries are usually rated at "CCA", or cold cranking amps, or "MCA", Marine cranking amps - the same as "CA". Any battery with the capability shown in CA or MCA may or may not be a true deep-cycle battery. It is sometimes hard to tell, as the term deep cycle is often overused - we have even seen the term "deep cycle" used in automotive starting battery advertising. CA and MCA ratings are at 32 degrees F, while CCA is at zero degree F. Sorry to say, the only positive way to tell with some batteries is to buy one and cut it open. Thus, this is not much of an option for you.

Remember there are three charging stages. Are you properly charging your battery?


Bulk charge is the first stage. Current will be sent to the batteries at the maximum safe rate. They will accept until voltage rises to near a full charge level. Voltages at this stage on average range from 10.5 volts to 15 volts. There is no "exact" voltage for bulk charging. There may be limits on the maximum current that the battery and wiring can take depending on the accessories that have been rigged.

Absorption charge is the second stage. Voltage remains constant and current little by little tapers off as internal resistance increases for the duration of the charging. It is during this phase that the charger puts out maximum voltage. Voltages during this phase are typically around 14.2 to 15.5 volts. The internal resistance increasingly goes up because there will less to be changed back to normal full charge.

Float charge is number three. After batteries reach full charge, charging voltage is reduced to a lower level (typically 12.8 to 13.2) to reduce gassing and prolong battery life. This is often referred to as a maintenance or trickle charge, since its main purpose is to keep an already charged battery from discharging. PWM, or "pulse width modulation" accomplishes the same thing. In PWM, the controller or charger senses petite voltage drops in the battery and sends very short charging cycles (pulses) to the battery. This may occur several hundred times per minute. It is called "pulse width" because the width of the pulses may vary from a few microseconds to several seconds. It is important to note that for long period float service, such as backup power systems that are seldom discharged; the float voltage should be around 13.02 to 13.20 volts.

Should you have any questions stop by the Tracker Service Department at the Bass Pro Shops in Myrtle Beach and ask for me.


Comments for Do you have the correct Marine battery for your boat?

Name: Michael H. Albritton
Time: Tuesday, October 2, 2012

I need two deep cycle marin e batteries connected in parallel with a trickle charger to power my amateur radio tranceiver. This will be in a hiouse and not a boat. The AFCI breakers will not let me hook upto the regular 110 outlet as the breakers trip. What sort of set up do you recommend for my particular case. I want something that is sealed an d that is of high quality and safe.

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