Schematics and Battery Bank Wiring


We receive requests from prospective clients that desire to view AC & DC schematics. There is a lot of valuable information readily available on the web site. However, AC & DC schematics are purposely not posted because there are too many variables that need to be considered. A small overview version typically used for our installations in a marine environment is shown below on the left. Below right is a small simple overview for an Off-Grid installation. Neither are complete views. If desired, ZRD will provide a custom electrical schematic that covers the major DC and AC components. It will show their relationships such that your plans for a desired electrical system upgrade or replacement will be assured and may be easily implemented. Also, if requested, additional components will be included in the schematics to assist future desired plans or expansions. This option, a $680 value, is provided free of charge when a major electrical system upgrade is purchased. Contact ZRD for details.

wiring overviews
The DC portion of the schematic should show the relationships between all DC sources (house battery bank, starting battery, primary and secondary alternators), charging equipment, DC panels, main electric draw items, bonding system, fusing, bus bars, ... The list is extensive and covers many different scenarios. Schematics need to be tailored to the specific configuration. This ensures clarity and prevents confusion. Otherwise, a schematic would need to be very large in size in order to cover every possibility. This would mean that the schematic would have items included that are not installed or appropriate for a given vessel, regardless of size.

The AC portion of the schematic should show the relationships between all AC sources, (shore power, genset, inverter, ..), selection mechanism(s) (manual, automatic, ...), and galvanic isolation equipment.

As discussed above, ZRD will design schematics for our customers as needed. They are tailored to their specific installations. Below is a simple overview for wiring up multiple Batteries in 3 configurations. Pay special attention to which Negative terminal is chosen to have the Main Negative Cable connected to. It is NOT the FIRST battery like the Main Positive Cable. It is at the END of the group.

Batteries wired in Parallel   Batteries wired in Series   Batteries first wired in Series then Parallel

• Batteries connected in Parallel
• Each Battery 12vdc, 255ah
• Voltage stays the same
• Capacity (amps) increases
(255 + 255 = 510ah)
  • Batteries connected in Series
• Each Battery 6vdc, 400ah
• Voltage gets added for total amount
(6 + 6 = 12vdc)
• Capacity (amps) stays the same
  • Batteries connected in Series and Parallel
• Each Battery 6vdc, 400ah
• First, Voltage gets added for each bank in series
(6 + 6 = 12vdc) X 2 banks
• Then, Capacity (amps) increases
(400 + 400 = 800ah)

  • Properly Wired Large Battery Bank in Series then Parallel

For ANY battery bank of ANY size that includes parallel wiring in any way (vs. only series), one MUST connect the Main Positive and Negative leads to terminals at opposite ends of the battery bank. Too add more batteries in parallel, one would just add them in the middle of the picture with appropriate similar wiring.
  Properly Wired Large Battery Bank in Series then Parallel

  • Properly Wired Large Battery Bank in Series then Parallel spanning Multiple Locations

Just like above showing a slightly different orientation.
  Properly Wired Large Battery Bank in Series then Parallel Spanning multiple Locations

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