Are you aware of this ABYC Update

[jssailem]

Reviewing the latest electrical information on Panbo, I found this article about the revisions to the ABYC standards regarding Over Current Protection (OCP).

abyc-publishes-updated-battery-and-electrical-standards

For all who are playing with their batteries, be they FLA or LiFePO4, this is an important update.

 

[Johann]

Some good stuff in there…. MRBFs are good for LFP 200Ah or less. You can now parallel two cables for ampacity if you follow a few rules. BMS with a normally open contactor can be the required switch. Inverter case grounds got a lot smaller. But the AIC requirement for large paralleled batteries is going to complicate some installs…

 

[colemj]

But the AIC requirement for large paralleled batteries is going to complicate some installs…

They don't even have to be paralleled batteries. A single 1000Ah 12V battery constructed from 4 1000Ah cells in series requires a fuse with a 50,000A IAC rating.

This moves one out of Class T and into NH and other types of industrial fuses and their associated mountings.

Even a single 500Ah 12V battery moves one into these large industrial fuses. A 400Ah battery is the largest that a Class T fuse still fits the recommendation, and a majority of boats are using batteries larger than this.

Here, I think the ABYC got over their skis again. They finally did the right thing by relaxing the fuse requirements for smaller batteries, but went overboard on the larger ones. Keep in mind that until this revision, they were ridiculously specifying 20kA AIC fuses for 50Ah LFP batteries, so I have little confidence that they understand this issue well.

ABYC continues to fail us on LFP battery recommendations.

Mark