Advanced Marine Electrics and Electronics Troubleshooting A Manual for Boatowners and Marine Technicians

18 electrical systems troubleshooting

The test indicates that the battery’s open-circuit voltage is

11.77 V. This is less than 25% of a full charge, as indi-

cated in the graph.

12.6

12.4

12.2

12.0

11.8

11.6

11.4

11.2

0% 25% 50% 75% 100%

voltage

Voltage

% Charge

Correlation Between % Charge

and Open-Circuit Voltage

The graph shows the correlation between open-circuit

voltage and battery state of charge.

First identify the location of the battery: is the battery in or

out of the vehicle (or in this case, the boat)?

Select the type of battery: flooded or AGM. For gel-cells,

select “regular” for the best results. (In this case, “flooded”

is synonymous with “regular.”)

Use the scroll keys to select the battery’s rating standard.

The typical choices are CCA (cold cranking amps), CA

(cranking amps), MCA (marine cranking amps), or DIN

(Deutsches Institut für Normung, a German industrial stan-

dard). Other options may be JIS (Japanese Industrial

Standard) and amp-hours (Ah).

Adjust the numerical amperage value to match the battery

rating. (This rating should be on the battery label.)

3

6

7

5

4

8