The following guide outlines the requirements for optimal battery life on a 12-volt battery system.

This guide is meant for standard, flooded lead-acid batteries and does not apply to other battery types such as sealed lead-acid, gel type batteries etc.

Flooded lead-acid batteries are currently the most popular and most cost effective for larger power storage needs such as in solar systems, power backup systems, automobiles and many other applications. Flooded lead-acid batteries have the cells submerged in an acid mixture and have removable caps on the top.

The advantages of standard lead-acid batteries include the reasonable up-front cost, capacity for the size and overall reliability and durability. Standard lead-acid batteries do however require some maintenance. A well-maintained battery pack can last ten years or more while a neglected and abused battery pack will only last three or four years. Good maintenance will improve system performance and greatly reduce battery bank replacement costs.

Proper Battery Maintenance

Never let the battery voltage drop below 11.3 Volts
If the battery voltage drops to 11.3 volts, it is then necessary to recharge the battery pack before it is used again.
Irreversible damage will be done to the battery if the voltage drops below 11.3 volts
A battery pack will last much longer if it is always kept above 12.0 volts. and is fully charged at least once every week

Battery Level Chart (measured in volts)

14.7 volts = Full Battery while charging
12.7 volts = Full Battery
11.8 volts = Low battery
11.3 volts = Dead Battery

Check the water level of the batteries once every 3 months. Remove the caps on top of the battery. The water level needs to be up to almost the bottom of the plastic lips, and the plates inside the battery need to be well covered with water. If the water level is low, add distilled water.
Important: Use only distilled water

Caution:
(Adding hard-water or contaminated water to a battery will reduce the useful life of the battery. Be careful with any battery system. Do not get battery acid in contact with skin or eyes.

Equalization: For best battery life on a flooded lead-acid battery an overcharge function at 15.2 to 15.4 volts is recommended once every three months for a one-hour period. (Do not equalize a maintenance-free battery)

This guide is intended to provide our customers and other users with the knowledge necessary to get optimal use of their batteries. This guide is not to be reused for any other purposes without the written consent of the writer.

Ben Zook
Belmont Solar
717-768-7796
ben@belmontsolar.com