Installation

Calculating Fuse/Circuit Breaker Size

Because your batteries can provide thousands of amps, you need fuses or circuit breakers that can safely withstand the short-circuit current that the batteries can produce.

To select the correct fuse type and size:

1.Determine the total cold cranking amp rating for your batteries. (The cold cranking amp (CCA) rating of each battery is displayed on the battery case. If it is not, contact the battery manufacturer to determine the CCA rating of your particular batteries.) For example:

•If you are using one battery to power your inverter and its cold cranking amp rating is 500 CCA, the total cold cranking amp rating is 500 CCA.

•If you are powering your inverter with two batteries connected in parallel, and each battery has a cold cranking amp rating of 500 CCA, the total cold cranking amp rating is 1000 CCA.

Note: For batteries connected in parallel, the total cold cranking amp (CCA) rating is the sum of the CCA ratings of all of the batteries connected in parallel.

2.Once you have determined the total cold cranking amp rating of your batteries, identify the corresponding Ampere Interrupting Capacity (AIC) of the fuse or breaker required for your system by referring to Table 3-5. (The AIC is the amount of battery short-circuit amperage that the fuse can safely withstand.)

Table 3-5 Cold Cranking Amps/ Ampere Interrupting Capacity1

Total Cold Cranking

Ampere Interrupting Capacity

Amps

(AIC)

 

 

650 or less

1500

651–1100

3000

over 1100

5000

 

 

1.The figures in Table 3-5are based on standards developed by the ABYC (American Boat and Yacht Council).

•If the Total Cold Cranking Amps indicate that the AIC needed is 2,700 amps or less, choose an ANL fuse.

•If the Total Cold Cranking Amps indicate that the AIC needed is up to 20,000 amps or if you require a “code fuse”, choose a Class T fuse.

3–12