BATTERIES, Trojan AGM & T-105, Used in prior models 2019 and older Elite II only

BATTERIES, Trojan AGM & T-105, Used in prior models 2019 and older Elite II only


Boost Charging
The term boost charging refers to fully charging your batteries before they are used or when they are in
Flooded Batteries
Two methods can be used to boost charge flooded batteries, either automatically or manually. If
using the automatic method (charger is preprogrammed), simply allow the charger to go through the
complete charge cycle.

If you use the manual method (charger has adjustable settings) follow the steps below:
  1. Boost charge at CONSTANT CURRENT, without voltage limit, at 3% of C₂₀ until the voltage stopsincreasing for three consecutive hourly readings. If using CONSTANT VOLTAGE, the recommendedboost charge voltage is 2.45 - 2.58 V/cell with the charger output current limited to 3 - 5% of C₂₀. Using voltages at the lower end of this range will result in an extended boost time.
  2. The boost charge is not complete until the specific gravity readings of each cell remain constant over three successive hourly readings and all cells are gassing freely. If you have questions concerning boost charging, contact the Battery Company Technical Support.
AGM / Gel Batteries
Similarly, two methods can be used to boost your AGM/gel product, automatically or manually. If using
the automatic method (charger is preprogrammed), just allow the charger to go through the complete
charge cycle. Make sure the proper battery type, AGM or gel, is selected on the charger.

If you use the manual method (charger has adjustable settings) follow the steps below:
  1. Boost charge at a CONSTANT VOLTAGE of (2.40 V/cell) with the current limited to 20% of C₂₀. Example: 20 amps for a battery with a C₂₀ of 100Ah.
  2. The time needed to boost charge the cells can be determined using the equation below. Depth of discharge (DOD) can be determined using the information in Table 7

For example, a 200AH battery bank taken down to a 50% depth of discharge(DOD) will need to be boost charged for 15 hours with a 10a charger or 10 hours with a 20a charger. 


Proper charging is imperative to maximize battery performance. Both under- or over-charging batteries
can significantly reduce the life of the battery. Most chargers are automatic and pre-programmed, while
others are manual and allow the user to set the voltage and current values.
AGM and gel batteries should always have temperature compensated charging.
  1. Batteries should be fully charged after each use. “Use” is defined as at least 30 minutes of runtime.
  2. Deep-cycle flooded/wet charging guidelines: Refer to Table 4 and Diagram 4.
  3. Deep-cycle AGM charging guidelines: There are various ways to charge AGM batteries. For optimum performance and life, Trojan recommends a 3-step profile as shown in Diagram 5 and following the guidelines in Table 5. 



Equalizing (deep-cycle flooded/wet batteries only)

Equalizing is an overcharge performed after fully charging deep-cycle flooded/wet batteries. An
equalizing charge prevents battery stratification and reduces sulfation which are leading causes of
battery failure. Trojan recommends equalizing every 30 days or when batteries have a low specific
gravity reading after fully charging, below 1.235, or have a wide ranging specific gravity of >0.030 points
between cells. Reference Section 8.3 for instructions on specific gravity measurement.

Deep-cycle AGM or gel batteries should NEVER be equalized.

Equalization can be performed either automatically (as programmed on the charger) or by following the
procedure below:
  1. Check the battery’s electrolyte level in each cell to make sure the plates are covered before charging.
  2. Check that all vent caps are secured properly on the battery before charging.
  3. Set charger to equalizing mode.
  4. The batteries will gas (bubble) during the equalization process.
  5. Measure the specific gravity every hour. Refer to Table 7 for specific gravity and voltage measurements. Discontinue the equalization charge when the specific gravity no longer rises.
WAR N I N G Do not equalize deep-cycle AGM or gel batteries.


  1. Charge batteries before placing in storage.
  2. Store in a cool, dry location, protected from the elements.
  3. Disconnect from equipment to eliminate potential parasitic loads that may discharge the battery.
  4. Batteries gradually self-discharge during transit and storage, so monitor the specific gravity or voltage in flooded batteries every 4 - 6 weeks. Monitor the open circuit voltage for AGM or gel batteries every 2 - 3 months.
  5. Batteries in storage should be given a boost charge when they are at 70% SOC for flooded and 75% for AGM or gel. Refer to Table 7 for specific gravity (flooded only) and voltage measurements for flooded batteries and AGM or gel batteries. If boosting is needed, refer to above boosting instructions.
  6. When batteries are taken out of storage, recharge before use.

Storage in Hot Environments (greater than 90°F or 32°C)

Avoid direct exposure to heat sources, if possible, during storage. Batteries self-discharge faster in
high temperatures. If batteries are stored during hot summer months, monitor the specific gravity or
voltage more frequently (approximately every 2 - 4 weeks).

Storage in Cold Environments (less than 32°F or 0°C)

Avoid locations where freezing temperatures are expected, if possible, during storage. Batteries can
freeze in cold temperatures if they are not fully charged. If batteries are stored during cold winter
months, it is critical that they are kept fully charged at all times.

What to Expect from Your Battery

  1. A new deep-cycle battery will not immediately deliver its full rated capacity. This is normal and should be expected since it takes time for a deep-cycle battery to reach maximum performance or peak capacity.
  2. AGM batteries will reach rated capcity in less than 10 cycles.
  3. Flooded batteries take between 50 - 100 cycles to achieve full, peak capacity.
  4. When operating batteries at temperatures below 80°F (27°C), they will deliver less than the rated capacity.
    1. For example at 0°F (-18°C) the battery will deliver 50% of its capacity and at 80°F (27°C) it will deliver 100% of its capacity.
  5. When operating batteries at temperatures above 80°F (27°C), they will deliver more than the rated capacity but battery life will be reduced.
  6. The life of a battery is difficult to predict and will vary by application, frequency of usage and level of maintenance.

Trojan Warranty & Troubleshooting

Contact Trojan Tech Support at 800-423-6569 ext. 3045 or

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