In Australia and New Zealand ASNZS5139:2019 has arequirement to have over-current protection between parallelbatteries. This may not be required in other countries, however,
could be considered best practice.
These requirements also include ingress protection requirements.
PowerPlus Energy offer the below to assist with systemsdesign.
The underlying intent is to provide not only compliance, but theability to use reasonabilitypriced equipment, however, this mayvary depending on your country, region, or supplier.