question

jsheehan avatar image
jsheehan asked

Do I need a 48V System Mega Fuse?

Hi,
Attached is my Wiring Diagram. I have purchased a 200A Mega Fuse 58V (For 48V Systems). I need a 100A Fuse between my MPPT and Battery. Does that also need to be a 100A Mega Fuse 58V (For 48V Systems)? Because the I can only find a 125A Mega Fuse for 48V Systems? So yeah I cant find one that is 100A.

screen-shot-2021-10-18-at-10214-pm.png

fuses
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3 Answers
shaneyake avatar image
shaneyake answered ·

The smallest 58V Mega Fuse that Victron sells is 125A. If you cable is correctly sized then you can use the bigger use. 35MM cable to the charge controller is recommended, 25mm is also probably fine depending on distance.

Multiplus-ii to bus bar should be 70mm and a run off less than 5m.

25mm to the batteries is probably fine but I personally would run 2 cables from batteries to bus bar as 25mm seems to small for me. I know the BMS would probably disconnect before the cable gets warm. You can fuse on the bus bars and then just install a disconnect switch if required. Not sure about your local code, in my mind that run is protected by BMS but that may not be acceptable.

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ahtrimble avatar image
ahtrimble answered ·

If you go with a #2 cable/wire your 125a fuse should be fine as long as it is kept fairly short, less than 15' round trip.

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rata1 avatar image
rata1 answered ·

Fusing a 48v MPPT into a Lynx/MEGA fuse holder - have a look at this "new" range at Mouser - below a 100A suitable for the Lynx.

https://www.mouser.co.uk/ProductDetail/IXYS-Integrated-Circuits/0998100.UX-2M8?qs=YCa%2FAAYMW02nAAwfLhrD6Q%3D%3D

Higher and lower currents available @70VDC. Their search engine isn't the best, so put

0998???.UX-2M8 into the search replacing ??? with the current you want.

Examples:

60A.- https://www.mouser.co.uk/ProductDetail/Littelfuse/0998060.UX-2M8?qs=YCa%2FAAYMW02cHMaIjHo6bg%3D%3D


80A - https://www.mouser.co.uk/ProductDetail/Littelfuse/0998080.UX-2M8?qs=YCa%2FAAYMW00I0Lo1SQ2Alg%3D%3D


100A - https://www.mouser.co.uk/ProductDetail/IXYS-Integrated-Circuits/0998100.UX-2M8?qs=YCa%2FAAYMW02nAAwfLhrD6Q%3D%3D


200A - https://www.mouser.co.uk/ProductDetail/Littelfuse/0998200.UX-2M8?qs=YCa%2FAAYMW036%252BTgOsHU%252Brg%3D%3D


Data sheet.


https://www.mouser.co.uk/datasheet/2/240/Littelfuse_MEGA70V_Datasheet-1532099.pdf


Hope this is of some use.

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