I looked long and hard at the class T fuse and went with a MRBF fuse instead. I think a lot of people on the forums go with a class T only because they think its better and don't review it against specific use cases. Here' a list of the issues I reviewed for the two types:
Fault Current Rating: Fuses needs to be rated to safely interrupt the fault current available from Li-on batteries. There's not a lot of info on the interweb about Li-on fault current availability but I found a white paper on it:
Temperature, Overcharge and Short-Circuit Studies of Batteries used in Electric Vehicles.
I have 8 cells in my 400A-Hr, 2P4S battery pile and I guesstimated the fault current at around 9,600A. The MRBF is rated for 10,000A so it should work for my battery. I can speak from multiple experiences that the MRBF will safely interrupt a fault from fat fingering a wrench while working on the battery hot. I would have gone with a class T, which is rated for 200,000A if I had a bigger battery.
Fuse Curve: I managed to find a time versus current curve for the MRBF and reviewed it against the class T. I prefer the MRBF as it has some overload capability, meaning it accommodates the in-rush current from motor starts. The class T is designed to interrupt faults as fast as possible and doesn't have much overload capacity. That's not a bad thing, especially for a battery with a lot of fault current, but the MRBF fits my use case a little better. I might want to add some A/C someday.
Listings: The MRBF is listed for ignition protection, SAEJ1117 and is manufactured by a real fuse company, Bussmann. While that's not the preferable UL listing that the class T has, it's a lot better than most fuses. No way would I use Mega or ANL type fuses, they're manufactured to a price point and not to any kind of real listing, IMHO.
Size: The largest MRBF fuse available is a 300A, which limited my inverter size to 2,000VA. I would have had to use a class T if I went with a 3,000W inverter. Also, the MRBF is physically a lot smaller than the class T so I could use one class of fuse for all my high current loads in the space I have. I stacked the MRBF terminals (no more than 2) to save space.
Cost: the class T is is expensive compared to the MRBF - $60 versus $15 on Amazon. I found MRBF in bulk for $7.50 each at Del City. Knowing myself I was pretty sure I would go through two or three of them during startup and I've gone through one so far. With the MRBF I could afford to buy some spares and throw them in the van, just in case.
Summary: An MRBF fuse is a cost effective alternative to the class T for a system with 400a-hrs or less of battery capacity and a 2,000VA or smaller inverter.
This is probably more that you wanted to know but I hope this helps.
Bruce
by bdosborn » Sat Apr 16, 2022 5:27 pm 
No corrosion issues either and I'm puzzled why it should be a problem when the battery manufacturer supplies the cells with bare copper bus bars. 
