MIDI vs MEGA fuse voltage drop / power loss

[bdl]

I'd have expected physically smaller fuses to have greater power loss than larger fuses - that is, a MIDI fuse to have greater voltage drop than a
MEGA fuse of the same rating.

However Victron's MIDI, MEGA and ANL fuses, and fuse holders data sheet says otherwise: https://www.victronenergy.com/uploa...,-Mega-and-ANL-fuses,-and-fuse-holders-EN.pdf

e.g. MIDI fuse 100A = 60 mV (= 6 W @ 100A); MEGA fuse 100A = 90 mV (= 9 W @ 100A)

I'd love to hear if anyone has any practical experience that can confirm or deny Victron's publication.

 

[BiduleOhm]

Smaller fuse = less power needed to melt = lower losses for same current than a bigger fuse

 

[timmeh]

so since midi has 5000a AIC and Amg has 2000a AIC then after your class t fuse on the battery which fuse would you use as a main on each fuse bank. For example 150a fuse? Since both midi and amg have a 150a option.

 

[bdl]

Smaller fuse = less power needed to melt = lower losses for same current than a bigger fuse

Revisiting this topic: I don't buy that reasoning - assuming the materials are the same, why wouldn't the 100A rated MIDI fuse have the same fusing element (i.e. the section within the fuse that actually fuses on overcurrent) as a 100A rated MEGA fuse? If anything, I'd expect the larger fuse to have slightly lower drop, as it would have slightly lower losses in the non-fusible parts (bolt contact area, etc).

Having said that I now realise that the physically larger fuse would also act as a better heatsink, drawing heat from the fusing element that would lower its effective fuse response. That would mean the physically larger fuse (more accurately, the fuse with the larger 'heatsink' attached) would need to have a smaller fusible element to get the same fuse response as the smaller fuse; ergo higher resistance and thus voltage loss. Of course, I may have just constructed a completely flawed thought experiment ;-)

In any event, the conclusion I draw from the above data sheets is to prefer smaller fuse sizes, i.e. don't go physically larger until you have to. e.g. MIDI over MEGA over ANL.

 

[BiduleOhm]

Revisiting this topic: I don't buy that reasoning - assuming the materials are the same, why wouldn't the 100A rated MIDI fuse have the same fusing element (i.e. the section within the fuse that actually fuses on overcurrent) as a 100A rated MEGA fuse? If anything, I'd expect the larger fuse to have slightly lower drop, as it would have slightly lower losses in the non-fusible parts (bolt contact area, etc).

Because as you said just after the bigger fuse will dissipate more power to reach the same temperature. Of course I assume both fuses use the same metal (so, same melting point).