Marshall Batteries
0800 228 837
Holler for a Marshall

Choosing the right Deep Cycle battery (see attachment)

 It is easy to decide which deep cycle battery is required and how long it will operate your equipment before recharging is necessary. First you need to establish:

    1.  The Loading of each piece equipment. This is expressed in watts and is stamped into the compliance plate attached to the electrical item.
    2.  The length of time (in hours) that it is intended to operate each piece of equipment between recharges.
    3.  The system voltage (6v, 12v or 24v).


The first step is to determine the total number of "Watt Hours" involved. Calculated this by multiplying the loading of each piece of equipment (watts) by the number of hours you intend to use it between recharges and then

add them up. Follow this example of a boat owner who is

operating a winch, fridge, communication equipment and

uses the interior lights for extended periods.


The next step is to determine "Ampere Hour" (AH) requirement that the battery must accommodate. You calculate this by dividing the watt

hours by the system voltage. Continuing the boat example:

500 Watt Hours/12 volts(system voltage)=42 Ampere Hours


Battery cables are not perfect so it pays to make allowances for loss of power. A cable loss margins of 10% is usually appropriate.

In addition, it's nice to have a little more capacity than you will need. Therefore, we recommend you build in an over-capacity margin of about 25%


Yes, deep cycle batteries can be used for engine starting purpose; but only as a back up of the existing starting battery. If it is used, you will need to increase

the Ampere Hour estimate by 50% to ensure you have starting power when the battery has been partly discharged.

Let's apply these additional factors to our boat example:


Having established the number of Ampere Hours required, refer to the Deep Cycle Battery Specification listing to choose the correct battery for your

Needs click.

There is one further consideration. Battery capacity varies according to speed of discharge. The faster the battery is discharged, the fewer Ampere

Hours it will deliver before requiring a recharge. Therefore, EXIDE Deep Cycle batteries are capacity rated for three lengths of discharge time. You will

need to determine the length of time your battery will be discharged over and match to the closest rated discharge time quoted.

If being discharged over a 20 hour period, then a ED6 type will be very suitable.


If in doubt then please contact our professional store network or Exide Australia or New Zealand.