Battery recommendation - anchor windless

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The fuse is to prevent something downstream from the battery overheating and catching fire. Fuses protect the wire, not the battery nor the device. If there is a short and the fuse has a low AIC then the short can arc across the fuse and continue to overload the wire increasing the risk of fire.
Some comparisons between land vehicles and boats is inappropriate.

Yea ok we see things quite differently, so perhaps we agree to differ. In my world anyone expecting a 200-400amp AIC fuse,is there to protect the wires are dreaming. Is there only to disconnect the battery in a sustained short in excess of its rating say 200 to 300amp AIC fuse and that presumes that the BMS has failed and presumes that the said failure of the BMS has continued to supply high current and that the said current or short is in excess of your IAC fuse, which is likely to be 150amps plus. You say "if there is a short " , where downstream is this short going to come from. The ONLY way AIC will help is if the BMS fails, and the short is on a downstream device, and that devices fuse or CB fails or welds & maintains a short/draw in excess of the AIC fuse ( say 200 to 300amps) and the said short would otherwise have caused a non AIC fuse to self weld. There are a lot of "ands" there. The short will come from a "device" and that device should have an appropriately rated fuse or Circuit breaker (less than the AIC fuse). Your 200 amp or 300amp AIC fuse will do nothing to protect a load or the wires if draw/short is less than its rating and your wires will not stand the sustained draw/short, even my 2x 000 gauge wont deal with sustained 200amps.
My comparisons are very appropriate in my view. I don't rely on smelling something burring and stepping out, and I do have a tender if so inclined.
I am happy to discuss it further if you wish (Email me) but think we (or perhaps I) are side tracking Brains post. So I should stop.

 

[Davidasailor26]

In my world anyone expecting a 200-400amp AIC fuse,is there to protect the wires are dreaming. Is there only to disconnect the battery in a sustained short in excess of its rating say 200 to 300amp AIC fuse and that presumes that the BMS has failed and presumes that the said failure of the BMS has continued to supply high current and that the said current or short is in excess of your IAC fuse, which is likely to be 150amps plus.

I think you’re confusing AIC with the fuse amp rating, or at least your explanation is. Your 000 cable is rated for 271 or more amps (depending on its insulation and whether it’s in an engine space). It should be protected with a fuse of around that amperage. If the wire chafes to ground it will short, and the fuse needs to interrupt that circuit before the wire overheats. That’s exactly what it’s there for and the whole point of having a fuse. If the fuse’s AIC is below the maximum amperage that your battery bank can provide it will weld closed - that’s the definition of an AIC. If the fuse welds closed the wire will burn. AIC’s are on the order of thousands of amps. A class T AIC is more thousands of amps than other fuse types, which is why it’s suitable for the amount of amperage a lithium bank can provide. The BMS might interrupt the current but cannot be relied on to do so, as it could weld itself closed too; again that’s why you need a fuse in the first place.

But back to the OP’s question - for a dedicated windlass bank (not a house bank where lithium certainly can be worthwhile), what would be the value gained from adding the complexity and cost of safely charging and maintaining lithium, instead of just putting in a couple AGMs and calling it good?

 

[jssailem]

what would be the value gained from adding the complexity and cost of safely charging and maintaining lithium, instead of just putting in a couple AGMs and calling it good?

 

[Foswick]

But back to the OP’s question - for a dedicated windlass bank (not a house bank where lithium certainly can be worthwhile), what would be the value gained from adding the complexity and cost of safely charging and maintaining lithium, instead of just putting in a couple AGMs and calling it good?

You are probably right. LiFePO4 can be a more space-efficient, cost-effective, and performant option. But, I do see a general trend toward lithium for its own sake, even when it doesn't necessarily make sense.

The devil is in the details.

In this thread, I want to point out that the original poster hasn't responded with any of those critical details. So, there is no way to know what is appropriate here. We can just speculate, based on what is likely. All we know is that they are looking for the "best" option and we don't even have a clear definition of what "best" means for this owner.

I tell people that with batteries (like many things), it largely comes down to when you want to spend your money. Generally, in the long run, LiFePO4 will be less expensive for better performance, provided it is used within its design parameters. But, again, there are a lot of details that make this more nuanced. The point at which AGM becomes more expensive can take well over 10 years to realize. In many cases, it is the next owner of the boat that will actually gain those cost benefits.

 

[mermike]

But back to the OP’s question - for a dedicated windlass bank (not a house bank where lithium certainly can be worthwhile), what would be the value gained from adding the complexity and cost of safely charging and maintaining lithium, instead of just putting in a couple AGMs and calling it good?

The reason to use LFP on a separate windlass bank are first, less weight up in the bow where it matters, and second, more capacity per cubic inch in an area that is already lacking space.

There are tradeoffs in running a windlass off the house bank or a dedicated bank, but it is not a complex installation. The cost delta between tens of feet of 2/0 or 4/0 cable, and smaller cable with a DC-DC charger is pretty small. It's a lot easier to pull smaller cable too.