Crown CR-390 390Ah 6VDC Deep Cycle Flooded Lead Acid Battery

Frequently Asked Questions

What is the Crown CR-390 battery?
The Crown CR-390 is a 6VDC deep cycle flooded lead acid battery rated at 390Ah at the 20-hour rate. It is designed for repeated charge and discharge applications including solar energy storage, renewable energy systems, backup power, RVs, marine equipment, electric vehicles, floor machines, and industrial equipment.

Is the Crown CR-390 suitable for solar energy storage?
Yes. The Crown CR-390 is designed for deep cycle use and can be used in off-grid solar systems, renewable energy storage, and grid-tied PV systems with battery backup. It is best suited to installations where flooded lead acid battery inspection, watering, and maintenance can be performed regularly.

How much energy does the Crown CR-390 store?
The Crown CR-390 is rated at 390Ah at the 20-hour rate and provides approximately 2.27 kWh of rated energy storage at that rate. Actual usable energy will depend on discharge rate, depth of discharge, temperature, battery condition, and system operating conditions.

How many Crown CR-390 batteries are needed for a solar battery bank?
The number required depends on the system voltage, daily energy use, backup requirements, solar production, inverter size, and desired depth of discharge. Because the Crown CR-390 is 6VDC:

• Two Crown CR-390 batteries in series create a 12VDC battery bank.
• Four Crown CR-390 batteries in series create a 24VDC battery bank.
• Eight Crown CR-390 batteries in series create a 48VDC battery bank.

Additional parallel strings can increase total amp-hour capacity when the system design requires more stored energy.

Charging & Maintenance

How should the Crown CR-390 be charged in a solar system?
Use a solar charge controller configured for flooded lead acid batteries and follow Crown's charging recommendations for the specific installation. The charge controller must be compatible with the voltage of the complete battery bank. Proper charging is important because chronic undercharging or excessive charging can reduce battery performance and service life.

Does the Crown CR-390 require watering?
Yes. The Crown CR-390 is a flooded lead acid battery and requires periodic electrolyte inspection and watering. Use distilled or de-mineralized water and maintain the electrolyte at the proper level. Watering frequency varies with charging voltage, cycling frequency, temperature, and battery age.

How often should I inspect the Crown CR-390?
A regular inspection schedule should be established based on the system's operating conditions. New flooded batteries should be checked regularly to establish a watering and maintenance baseline. Hot environments, frequent cycling, and aggressive charging may require more frequent inspections.

Can I use tap water in the Crown CR-390?
No. Use distilled or de-mineralized water when servicing the battery. Minerals and impurities in tap water can contaminate the electrolyte and negatively affect battery performance and service life.

Does the Crown CR-390 need ventilation?
Yes. Flooded lead acid batteries can produce hydrogen gas during charging. Install the Crown CR-390 in a properly ventilated location and keep it away from sparks, flames, cigarettes, and other ignition sources.

Crown Battery Comparison

How does the Crown CR-390 compare with the Crown CR-370?
The Crown CR-390 and Crown CR-370 are both 6VDC BCI Group 903 deep cycle flooded lead acid batteries with the same listed dimensions. The Crown CR-390 provides 390Ah compared with 370Ah for the Crown CR-370, increasing rated 20-hour energy storage from approximately 2.15 kWh to 2.27 kWh. The Crown CR-390 is also heavier, so the CR-370 may be preferable when slightly lower capacity and weight are acceptable.

What is the difference between the Crown CR-390 and Crown CR-350?
The Crown CR-390 and Crown CR-350 are both 6VDC deep cycle flooded lead acid batteries, but the Crown CR-390 uses a larger BCI Group 903 form factor than the Group 902 Crown CR-350. The Crown CR-390 provides 390Ah and approximately 2.27 kWh of rated 20-hour energy storage, while the Crown CR-350 provides 350Ah and approximately 2.04 kWh. The Crown CR-350 is smaller and lighter, while the Crown CR-390 offers greater capacity.

Solar Application & Battery Life

How deeply should the Crown CR-390 be discharged in a solar system?
For regular solar cycling, avoiding unnecessary deep discharges can help extend battery life. A properly sized battery bank can reduce the need for excessive daily discharge and provide additional capacity for periods of low solar production.

How long can the Crown CR-390 last in a solar application?
There is no single lifespan that applies to every Crown CR-390 installation. Service life depends on depth of discharge, charging, temperature, watering, maintenance, cycling frequency, and other operating conditions. Proper charging and shallower cycling can help support longer service life.

Can the Crown CR-390 be installed on its side?
No. The Crown CR-390 is a flooded lead acid battery containing liquid electrolyte and should be installed upright. Proper positioning also allows the battery to be inspected and serviced correctly.

Is the Crown CR-390 maintenance free?
No. The Crown CR-390 is a flooded lead acid battery and requires periodic electrolyte inspection and watering. Customers who want less routine maintenance may consider Crown AGM technology, but the replacement must be compatible with the solar system's charging equipment, voltage, physical space, and energy requirements.

What should I check if the Crown CR-390 is not performing as expected?
Start with a visual inspection for damaged cases, loose or corroded terminals, cable problems, and low electrolyte levels. The battery should be fully charged before testing. Persistent low performance can be associated with undercharging, sulfation, excessive discharge, low electrolyte, high temperature, poor connections, or battery age.