Home Marine batteries How to charge deep cycle marine batteries

A deep cycle marine battery has a long service life, is resistant to strong discharges, and quickly replenishes its nominal capacity.

It is also capable of maintaining high values of the discharge current for a long time. This battery is characterized by increased tightness and shock resistance. However, for the effective use and preservation of the service life of batteries, it is necessary to follow the rules and know the basis for how long to charge a marine battery.

Rules for charging deep cycle battery

Regarding the question of how long and properly to charge a marine battery, you need to follow the recommendations below:

  • Avoid charging the battery to 100% and discharging it to 0%. For example, lithium batteries do not have a memory effect and do not need to be fully discharged. If possible, stick to a 10-20 to 90% charge level.
  • Charge the battery at room temperature after each use. At negative temperatures, energy storage devices perceive the charge worse and are unable to reach the nominal capacity.
  • Do not charge the battery even at high temperatures. If the battery heats up to +50°C / 122°F. Its recharging will have to be suspended due to a violation of safety requirements.
  • Charge a discharged battery without delay. You can leave it in a discharged state for no more than 2 days.
  • Charge lithium traction batteries with dedicated chargers with CC / CV charging algorithm so as not to interfere with the required current supply parameters.

Algorithm of actions for recharging traction batteries

We will describe in stages how to properly charge the marine battery so as not to harm it. It is permissible to recharge the battery without removing it from the boat. It is important to ensure that the charging port or connector is clean and dry before charging.

We recommend recharging the deep cycle marine battery after each use at any convenient time. The recharging process ends when the cells reach a voltage of 3.6 V. The 24 V lithium batteries are charged at a voltage of 29.2 V and 12 V models – at a value of 14.6 V. The voltage of the maintenance charge is 26.5 and 13, 25 V.
Nevertheless, for batteries of different brands, the charging voltage may differ, therefore, in addition to the type of traction battery, the recommendations of the manufacturers must be taken into account.

The charging current depends on the type of battery and is indicated as a percentage of the capacity. As the charging current increases, the recharging process speeds up, but the risk of overheating and destruction of the battery increases. The duration of recharging traction batteries depends on the capacity to be restored, the charging current, and the type of battery. The more the battery is discharged and the lower the charging current, the longer the recharging process takes, and vice versa.

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