Input breaker recommendation for Victron Orion-Tr 48/24-12 DC-DC converter

[boxvan]

I'm trying to find a DC-rated mini breaker to put between my EG4-LL 48V battery (+) and Orion-Tr 48/24-12A isolated DC-DC converter. Victron says (in this manual) that the 48V model doesn't have an input fuse. Can anyone recommend an appropriate breaker that is rated for DC?

Is my math bad? 280W output / 0.89 (efficiency %) = 315W input, 315W / 48V / 0.80 (rated current %) = 8.2A, round up to 10A breaker? Will this work? https://windandsolar.com/dc-mcb-mini-circuit-breaker/

 

[Tomthumb62]

Some people trust breakers, but I wouldn't. The trustworthy breakers are usually pretty expensive. I personally prefer to fuse+breaker, but only use the breaker as a on/off switch.

These are popular and fairly inexpensive for a DC breaker (this one is 50A, but they have other models):

https://a.co/d/h3EOVwB

Note that this brand CHTAIXI has versions that are green colored on the labels and handles and other models that are blue. Someone told me that the they have seen the green ones fails but not the blue ones. No idea if that's true or not, but I have one installed in my trailer as an on/off switch for PV input and so far, so good.

To wire these...input source goes in to the TOP of the breaker and output to the battery goes out from the BOTTOM. It's not exactly clear on the device itself.

 

[boxvan]

Some people trust breakers, but I wouldn't. The trustworthy breakers are usually pretty expensive. I personally prefer to fuse+breaker, but only use the breaker as a on/off switch.

Thanks a ton, this sent me down the rabbit hole to learn about breaker tripping curves and fuse types and has me rethinking my approach. Does the math seem okay, as far as selecting 10A?

 

[Tomthumb62]

Thanks a ton, this sent me down the rabbit hole to learn about breaker tripping curves and fuse types and has me rethinking my approach. Does the math seem okay, as far as selecting 10A?

Can’t say. For the breaker I linked, I don’t think I would trust it alone. Probably very decent but if you lose the quality control lottery, it could be bad. I would better trust the Blue Seas or Bussman breakers. Or do what I do and use a fuse + CHTAIXI breaker as a switch only.

 

[ShaneC]

You could get a Din rail fuse holder and a 10A fuse. The fuses are standard sizes and cheap to replace. You don't need anything too expensive for this use.

I'd probably just use a breaker though, Tomzn also gets recommended here a bit so I went with them as I could get them on ebay. At the end of the day you're mostly protecting your cables. The DC/DC converter shouldn't fail if too great a load is placed on the output side. I'd expect to simply see the voltage drop.