Frequently Asked Questions
What is the Crown CR-305 battery?
The Crown CR-305 is a 6VDC commercial deep cycle flooded lead acid battery rated at 305Ah at the 20-hour rate. It is designed for repeated charge and discharge cycles and can be used in solar energy storage, renewable energy systems, backup power, RVs, marine equipment, electric vehicles, floor machines, and other demanding applications.
Is the Crown CR-305 a good battery for solar energy storage?
Yes. The Crown CR-305 is designed for deep cycle use and is suitable for off-grid PV systems and other renewable energy applications. Its flooded construction is particularly useful where the batteries can remain upright, properly ventilated, and regularly inspected and maintained.
How much energy does the Crown CR-305 store?
The Crown CR-305 is rated at 305Ah at the 20-hour rate and provides approximately 1.78 kWh of rated energy storage at that discharge rate. The amount of energy available to a solar system will vary with discharge rate, temperature, battery age, charging condition, and depth of discharge.
How many Crown CR-305 batteries are needed for a solar battery bank?
The required number depends on the system voltage, daily energy consumption, desired backup time, solar production, inverter requirements, and allowable depth of discharge.
Common series configurations include:
- Two Crown CR-305 batteries in series create a 12VDC battery bank.
- Four Crown CR-305 batteries in series create a 24VDC battery bank.
- Eight Crown CR-305 batteries in series create a 48VDC battery bank.
Additional parallel strings can be used when more amp-hour capacity is required. Series and parallel configurations should be designed carefully so that the batteries are matched and charged consistently.
What type of applications are suitable for the Crown CR-305?
In addition to solar energy storage, the Crown CR-305 can be used in RVs, marine systems, golf and electric vehicles, floor cleaning equipment, aerial equipment, industrial equipment, and other applications requiring repeated deep cycling. For solar installations, the battery should be installed according to the applicable system and battery manufacturer's requirements.
Charging & Maintenance
How should the Crown CR-305 be charged in a solar system?
Use a solar charge controller with a charging profile appropriate for flooded lead acid batteries and follow Crown's recommended charging requirements. Avoid chronic undercharging because it can contribute to sulfation and reduced capacity, while excessive charging can increase water loss and shorten battery life.
Does the Crown CR-305 require watering?
Yes. The Crown CR-305 is a flooded lead acid battery and requires periodic electrolyte inspection and watering. Use distilled or de-mineralized water only. Watering should normally be completed after the battery has been fully charged.
How often should I check the water level in the Crown CR-305?
The correct interval depends on cycling frequency, charging practices, battery age, and operating temperature. Crown recommends inspecting new flooded deep cycle batteries about every two weeks to establish a watering baseline. As the battery ages or operating conditions change, weekly inspections may be appropriate.
Can I use tap water in the Crown CR-305?
No. Use distilled or de-mineralized water. Minerals and other impurities in tap water can contaminate the electrolyte and negatively affect battery performance and service life. Do not add sulfuric acid during normal watering maintenance.
Does the Crown CR-305 need ventilation?
Yes. Flooded lead acid batteries can release hydrogen gas during charging. Install the Crown CR-305 in a properly ventilated location and keep it away from sparks, flames, cigarettes, and other ignition sources.
Crown Battery Comparison
What is the difference between the Crown CR-305 and Crown CR-330?
The Crown CR-305 and Crown CR-330 are both 6VDC Group 902 commercial deep cycle flooded lead acid batteries. The Crown CR-330 provides 330Ah at the 20-hour rate compared with 305Ah for the Crown CR-305, giving it more rated energy storage and reserve capacity. The Crown CR-305 is slightly lighter and provides a lower-capacity option when 305Ah is sufficient for the system.
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Specification
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CR-305
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CR-330
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Voltage
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6VDC
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6VDC
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Capacity (20 Hr)
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305Ah
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330Ah
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Capacity (5 Hr)
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255Ah
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270Ah
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Storage kWh (20 Hr)
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1.78 kWh
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1.92 kWh
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Reserve Capacity
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170 min @ 75A
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190 min @ 75A
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Dimensions
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12.19 x 7.19 x 14.13 in (31.0 x 18.3 x 35.9 cm)
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12.19 x 7.19 x 14.13 in (31.0 x 18.3 x 35.9 cm)
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Weight
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90 lbs (40.8 kg)
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93 lbs (42.2 kg)
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Terminal Type
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Dual post/Stud combination
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Dual post/Stud combination
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How does the Crown CR-305 compare with the Crown CR-350?
The Crown CR-305 and Crown CR-350 are both 6VDC Group 902 flooded deep cycle batteries with the same listed physical dimensions. The Crown CR-350 increases capacity to 350Ah compared with 305Ah for the Crown CR-305, making it better suited when additional energy storage is needed without changing the battery footprint. The Crown CR-305 is the lighter and lower-capacity option.
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Specification
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CR-305
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CR-350
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Voltage
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6VDC
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6VDC
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Capacity (20 Hr)
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305Ah
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350Ah
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Capacity (5 Hr)
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255Ah
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290Ah
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Storage kWh (20 Hr)
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1.78 kWh
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2.04 kWh
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Reserve Capacity
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170 min @ 75A
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210 min @ 75A
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Dimensions
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12.19 x 7.19 x 14.13 in (31.0 x 18.3 x 35.9 cm)
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12.19 x 7.19 x 14.13 in (31.0 x 18.3 x 35.9 cm)
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Weight
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90 lbs (40.8 kg)
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101 lbs (45.8 kg)
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Terminal Type
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Dual post/Stud combination
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Dual post/Stud combination
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Solar Application & Battery Life
How deeply should I discharge the Crown CR-305 in a solar system?
Avoid unnecessarily deep daily discharges when possible. Crown's published cycle-life testing shows that shallower discharge levels can provide substantially more cycles than repeated 100% depth-of-discharge cycling. A solar system should therefore be sized with enough battery capacity to avoid routinely exhausting the battery bank.
How long can the Crown CR-305 last in a solar application?
Battery life depends on depth of discharge, charging, temperature, maintenance, and operating conditions. Crown's published stationary cycle testing for the CR-305 estimates approximately:
- 450 cycles at 100% depth of discharge
- 1,050 cycles at 50% depth of discharge
- 1,310 cycles at 40% depth of discharge
- 2,600 cycles at 20% depth of discharge
These are test estimates under stated conditions and should not be treated as a guaranteed field lifespan.
Can the Crown CR-305 be installed on its side?
No. The Crown CR-305 is a flooded lead acid battery containing liquid electrolyte and should be installed upright. Keeping the battery upright also allows proper inspection, watering, and servicing.
What should I check if my Crown CR-305 is not holding a charge?
First check that the battery bank is being fully charged and that the charge controller is configured for flooded lead acid batteries. Also inspect the terminals and cables for corrosion or loose connections and verify the electrolyte level. Persistent low capacity can be related to undercharging, excessive discharge, sulfation, temperature, low electrolyte, poor connections, or battery age.
How should I store the Crown CR-305 when it is not being used?
Store the battery fully charged in a cool, dry, ventilated location and protect it from extreme temperatures. Flooded batteries can self-discharge while stored, so the battery should be checked periodically and recharged as needed. Before long-term storage, inspect the battery and maintain the electrolyte at the proper level.
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