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Julia Ashmun posted a status
Apr 17
For anyone who is considering or has already switched from wet-cell batteries (starter and/or house bank) to non-wet cell batteries (e.g., AGM, FireFly, Gel, Lithium, etc.), please consider installing a Blue Sea Class-T fuse (or at least a terminal fuse) near the non-wet cell battery to protect all of your fuses (e.g., ANL, etc.) and circuit breakers down steam.

Our old boats were never designed for the 5k-6k short circuit amps/per battery (3 house batteries is over 15k short circuit amps) that non-wet cell batteries can generate when something goes wrong (e.g., chafing, accidental 2” screw, battery failure/bad cell, etc.). That amount of short circuit amps can jump/arc an ANL fuse or melt a circuit breaker before it can trip. A simple Blue Sea Class-T fuse (20k short circuit amps) for $50+/- is cheap insurance for protecting you and your boats electrical system.

And I say Blue Sea because I recently watched a solar install video where the Lithium batteries had “off-brand” ANL fuses that were really heating up the ANL fuse, the crimp, and the 2/0 cable near the fuse/crimp. Once the customer replaced the “off-brand” ANL fuse with Blue Sea the temp problem went away (as seen with a temp gun). Needless to say, I recommended a Class T fuse to him, too..

I’ll get off my soap box now but I will say in closing that the #1 cause of boat fires is DC wiring and that percentage has been going up over the last decade. Even center-consoles with outboards are going up in smoke when there starter cable and other wires catch fire. So if you think the problem is your old battery, please check the voltage drop on the old cable first to ensure the cable is not corroding.

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  • Im using MRBF fuses at the batteries.  I think these are a good option as well. Mainsail has a video where he intentionally shorts a 400 Ah lithium bank and the fuse pops instantly.

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