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General charging information for AGM and GEL batteries

  1. Only charge GEL batteries using a confirmed and reliable, temperature sensing, voltage regulated charger. Never use a constant current charger!
  2. Charging Current or Amps is the flow of electricity. Every battery can only store, deliver or receive a certain amount of electricity. Voltage is electrical pressure. The amount of voltage dictates the rate at which the amps will be forced into the battery during the re-charge process. The temperature at which this process is taking place also effects charging. When the right pressure is used – at the right temperature – the battery will be charged at its optimal rate. If to much pressure is used, current or charge will be forced through the battery faster than it can be stored. This will cause the battery to give off hydrogen and oxygen faster than it can be recombined leading to the destruction of the battery. A warmer battery accepts re-charge easier
  3. At 25°C/77°F keep charging current in the range of 2.38 volts to 2.42 volts per cell for GEL cell batteries.
  4. At 25°C/77°F keep charging voltage in the range of 2.4 volts to 2.465 volts per cell for AGM batteries
  5. Compensation for battery temperature above or below 25°C/77°F can be made by subtracting 0.005 volts per cell for each 1°C above 25°C or by adding 0.005 volts per cell for each 1°C below 25°C. Add .028 volt per cell for every 10° below 77° F and subtract .028 volt per cell for every 10° above 77° F
  6. When re-charging - consider that to replenish the ampere hours removed in the discharge process - you will need to replace 104% to 112% of the charge removed. Also, the time it will take to re-charge will depend on certain variables such as the depth of the discharge, the ambient and battery temperature, the age/condition of the battery and the chargers overall features. Typically you should expect that it will take 60% of the charge time to return the battery to within 90% of its original capacity. It will take the remaining 40% of the charge time to completely recharge the battery
  7. The process of re-charging a battery should be considered completed when the charge rate drops below or equal to the batteries self-discharge rate. For example a 100AH battery with a 3% self discharge rate should be considered to be re-charged when the charge rate reaches and remains stable at 3 amps

Warning: Do not equalize charge GEL or AGM batteries!

Equalizing is an over voltage-over charge performed on flooded lead acid batteries after they have been fully charged. It helps to eliminate stratification and sulfation, two of many conditions that can reduce the overall performance and life of a flooded battery. Laboratory designed, specific to Discover®, balance charge algorithms have been designed and are included in all Discover® recommended Industrial Commercial charges offered for sale wherever our Discover® VRLA products are sold. Visually the Balance Charging curve is similar to an flooded equalize charge curve in its finishing voltage, but it is strictly controlled to promote active material conversion and not to prevent acid stratification. Discover’s® balance charging algorithms are highly recommended for batteries being installed in strings, larger batteries using taller plate groups and/or with batteries constantly being subjected to high rate deep discharge.

General Lead Acid Battery Description
General Lead Acid Battery Applications
General Lead Acid Battery Types
General Lead Acid Battery Chemistry
Discover® Sealed Valve Regulated Lead Acid Batteries
Discover® Deep Cycle AGM Battery
Discover®700 Series Dry Cell Battery
Discover® EV Traction Dry Cell Battery
General Benefits and Features of Discover Valve Regulated Lead Acid (VRLA) Technology
Sales Channels for Discover Battery Technologies
Things to question when making a battery buying decision
What to consider when buying a deep cycle battery
Information gathering before buying batteries
Calculating cost to own when purchasing batteries
Safety First
Safety and Productivity
When working with batteries
When handling battery acid
When installing or replacing batteries
When booster cables are used
Danger of exploding batteries
Warning and warning labels
Parallel connections for sophisticated users and installers
Parallel connections for unsophisticated users and installers
When charging batteries
Selecting a charger
General charging information for AGM and GEL batteries
GEL battery charging
AGM battery charging
Equalizing (Flooded batteries only)
Typical self-discharge of VRLA batteries at different temperatures
Typical self-discharge of high quality deep cycle flooded batteries at different temperatures
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