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Battery Charging Basics

  • Cycle new batteries lightly (20% or less depth of discharge) the first few cycles. This helps complete the forming process of the plates (in case they are not completely finished forming).
  • Always allow batteries to "cool off" after charging. The cooling time is very important because heat is generated during the recharge and discharge cycles. Without the cooling time the heat grows, accelerating grid corrosion, which is one of the major causes of battery failure.
  • Opportunity charging (quick charging between uses) is detrimental to battery life. While it is true that the shallower the cycle, the more cycles the battery can deliver, opportunity charging is not good because the cooling time is eliminated, shortening life. (I.e. One charge cycle per day is preferable.)
  • Never charge a wet battery with a sealed (gel cell) battery charger. Use the charger that comes with the golf cart. The wet battery needs the higher voltages to finish the charge and without it, the batteries never come back to 100% and sulfation can occur.
  • Never let the electrolyte level of a wet battery fall below the plates. Lack of maintaining the electrolyte in a wet battery causes damage (sulfation) to the exposed portion of the plate, which reduces capacity.
  • Never store a battery in a discharged state. The sulfate that will form during discharge should not be ignored for an extended time period because severe sulfation takes place sometimes, making the battery impossible to recharge fully.
  • Always keep the tops and terminals of batteries clean and free of corrosion. The film on top of the battery can cause the current to migrate between the posts, accelerating self-discharge.
  • A fully charged battery will give you the best and longest service. Be sure the batteries are fully charged before testing or using your Golf Cart. A fully charged battery, without a drain or load, after the surface charge has dissipated, is: 
  • Always fill your Golf Cart deep cycle batteries with distilled water after they have been charged. If the electrolyte level is at least above the plates, do not fill the battery until after recharge. The electrolyte expands during charging and if you fill them before recharging, the electrolyte will possibly bubble out of the battery. The plates must be covered with electrolyte for recharge but be careful not to overfill.
  • Do not discharge Deep Cycle batteries below 50% State of Charge. If this happens, the State of Charge may be too low for the Charger to activate and charge the batteries. This will necessitate “jump starting” the battery(ies) with like-size batteries. In other words, a 48-Volt Golf Cart will need another 48-Volt system to jump start it and bring the charge up high enough so the Charger can take over and finish charging the system.
  • An overly discharged battery may need to be cycled a few times before it can recover fully. If a battery begins to heat before coming up to a full state of charge, it may be necessary to discharge the battery and recharge it a few times. This charge and discharge cycle may help the current acceptance of the battery and facilitate its recovery to a usable condition.
  • In situations where multiple batteries are connected in parallel, series or series/parallel, a replacement battery(ies) should be of the same size, age and usage level as the companion batteries. Do not put a new battery in a pack that has used 50 or more cycles. Either replace with all new or use a good used battery(s). The older batteries will draw down the performance and life expectancy of the new ones. The older the batteries are, the larger the negative impact they will have on the new batteries.
  • When replacing old batteries, it is good practice to replace the connecting cables at the same time. Corroded terminals connectors can be replaced but often times corrosion is hidden inside the insulation jackets of the cables. Corrosion will always increase resistance to electrical conductivity and excessive resistance will cause excessive heat.
  • Deep Cycle batteries need to be equalized periodically. Equalizing is an extended, low current charge performed after the normal charge cycle. It helps keeps cells in balance. Actively used batteries should be equalized once per week. Manually timed chargers should have the charge time extended about 3 hours. Automatically controlled chargers should be unplugged and reconnected after completing a charge cycle. Newer Smart Chargers will often have an Equalization Cycle programmed into it.
  • As batteries age, their maintenance requirements change. Generally, their specific gravity is higher. Gassing voltage goes up. This means longer charging time and/or higher finish rate (higher amperage at the end of charge). Usually, older batteries need to be watered more often. And, their capacity decreases.
  • Inactivity can be harmful to deep cycle batteries. If they sit for several months, a "boost" charge should be given; more frequently in warm climate (about once a month) than in cold (every 2-3 months). This is because batteries discharge faster at higher temperatures than at colder temperatures.