I run on 51V with 15S LiFePO4 cells.
I ended up doing a 12V bus as my surveilance system needs 12V, so the Pi will then run from 12V. I’ll post pictures when it’s all done.
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I have bought this voltage regulator to connect my Raspberry Pi running Venus to the 48V DC bus, its a Buck Voltage Regulator, Voltage IN 9-120V and Voltage OUT 5V @ 3A
Can I use a 32V, 1A DC blade fuse between the battery and regulator? The output is only 15W or 5V at 3A. Not sure what the input wattage is but I doubt its very much as the conversion efficiency is around 96%, so roughly 0.5A @ 50V. Very rough numbers obviously.
Is a 32V DC rated fuse safe at 48V DC when the current draw is very low? Am I over thinking things?
These are automotive fuses so not recommended for 48V.
You should use a 10 x 38 mm ceramic fuse.
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I’ve only seen 1000V 10 x 38 ceramic fuses, I currently use them on my PV strings with mini circuit breakers. Do you get lower voltage ceramic fuses or does the voltage not matter as long as the voltage rating is higher than the circuit voltage?
I could always just use a MCB instead?
Sure you can use a MCB. Just check that it’s rated for 48V dc! (MCBs have an AC and a DC rating)
DC is no different from AC ito power but switching it off is difficult because it arcs. (The air ionises and then the resistance drops allowing the arc to sustain…)
DC switchgear use clever techniques to prevent this: The 10x38mm ceramic fuses are filled with a sand which will fill the space of the fuse once it has blown thus extinguishing the arc.
This Youtube video must be a classic: AC versus DC load breaking comparison with a knife switch - YouTube
Voltage on fuses are for the rating. It means they are safe to use up to that voltage. So you can safely use them at lower voltages.
Groetnis
You could use a Megafuse. They have both 32V and 58V models, and you can get ANL fuses (very similar) up to 80V. Just note that the price difference between the 32V and higher voltage options is significant. Where the 32V model can be had for under R100 in the right place, the 58V option is 5 times more expensive.
The 10x38 fuses, by comparison, are then quite affordable. I think the last batch I bought worked out about R60 per fuse, though it is probably a bit more by now.