Calculating Fuse/Circuit Breaker Size
Because your batteries can provide thousands of amps of short-circuit current, 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 short-circuit current rating for your batteries. For example:
•If you are using one battery to power your inverter and its short- circuit current rating is 500 A, the total short-circuit current rating is 500 A.
•If you are powering your inverter with two 12 V batteries connected in parallel, and each battery has a short-circuit current rating of 500 A, the total short-circuit current rating is 1000 A.
•If you are powering your inverter with two 6 V batteries connected in series, and each battery has a short-circuit current rating of 500 A, the total short-circuit current rating is 500 A.
Important: For batteries connected in parallel, the total short-circuit current rating is the sum of the short-circuit current ratings of all of the batteries connected in parallel. For batteries connected in series, the total short-circuit current rating is equal to the short-circuit rating of a single battery.
2.Once you have determined the total short-circuit current rating of your batteries, pick the fuse/circuit breaker’s interrupt capacity based on the short-circuit current calculated in step 1.
3.Choose a fuse/circuit breaker with a correct current rating.
Fuses can be bought at any marine supply store, RV supply store, or electrical products store.
