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Parallel connections for unsophisticated users and installers

For unsophisticated users and installers when connecting in parallel, only use new and identical batteries.

If you connect two 12-volt batteries in parallel and they are identical in type, age and capacity, you can potentially double your original capacity. If you connect two that are not the same type, you will either overcharge the smaller of the two, or you will undercharge the larger of the two. If you connect two identical – but one older – you will definitely reduce the life of the new one.

When connecting in series or parallel and to prevent recharging problems, do not mix old and new batteries or ones of different chemistries or performance abilities. Cable lengths should be kept short and cabling must be sized large enough to prevent significant voltage drops. There should be a maximum drop of 0.2 volts (200 milli-volts) between batteries.

To increase the voltage of a system you must connect multiple batteries in Series (See Figure 3).

To increase the capacity (amp hours, reserve capacity) connect multiple batteries in Parallel (See Figure 4).

To increase both the systems voltage and the capacity, connect multiple batteries in Series and in Parallel (See Figure 5).

Figure 3 - To Increase Voltage Connect in Series

Figure 4 - To Increase Capacity Connect in Parallel

Figure 3 - Series Connections

Figure 4 - Parallel Connections

Figure 5 - Series/Parallel Connection

If more capacity is required, multiple batteries can be connected in parallel (positive terminal of battery 1 to the positive terminal of battery 2 and so on and so forth).

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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Tables & Figures