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Parallel connections for sophisticated users and installers

While most manufacturers state not to install more than 4 strings of paralleled batteries, it is possible to have more strings in parallel without reducing the life of the battery or the batteries getting out of balance.

If these requirements are fulfilled, paralleling of up to 10 strings is possible:

The same voltage drops must be realized from each string to the end connection (load and ground) regardless if the string consists of one unit (single cell or monobloc) or several units

  • This can be achieved by proper choice of cable lengths, cable diameters and arrangement for crosswise connection configurations
  • The connector cables for positive and negative terminals of each battery string must have the same length
  • The minimum cable size for the end connectors of a string is 25mm²/100 Ah of string capacity
  • The end-connector cables must be placed on a copper bar with at least 100mm²/100 Ah of string string capacity with the shortest possible distance
  • It is a must to have a circuit breaker for each string
  • The strings must have all the same number of cells
  • Each string must be exposed to the same heat or temperature potential

The performance data of all of the batteries has to be applied to the end terminal of each string. By using this parallel string configuration the reliability of the system is increased due to the redundancy. Neither battery life or reliability will be affected if this form of paralleling is done correctly. Parallel connection of strings with different capacities as well as different ages is possible (the age and capacity of the batteries within each string should be the same). The current during both discharge and charge will be split according to the capacity or age of the batteries respectively. Also, the type of lead-acid batteries may differ as long as the required charging regime and voltage (Vpc) per string is guaranteed.

Always connect the individual series strings first and then check that the different strings are at the same potential before connecting them together.

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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