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diy solar

Class T fuse sizing

Rlsimon

New Member
Joined
Dec 15, 2024
Messages
4
Location
South Louisiana
Not solar related but I figured I’d give it a shot here.
After reading through posts it looks like class T is the go to for lifepo4 builds. I’m hoping to get some sizing opinions from some of the much more knowledgeable people here.

Polaris Ranger 48v EV
Sevcon 650 amp controller
Two home brewed 16S/48V packs paralleled. Made with 74AH cells (180c,600 pulse)
Each will have its own BMS. 300c/600p

People who have converted these utv’s say they rarely see 400 amps. Briefly on long, steep grades wide open but possible. The controller is fused at 250 amps from the factory with the LA batteries. Seems I need a fuse between each battery and the bus bar and between the bus bar and controller. What sizes would I need? Main priorities are more safety and reliability. I don’t want cut it too close and start burning $50-&100 fuses but I definitely wouldn’t want to burn my shop down! I’m definitely open to any suggestions or alternatives.
 

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Fuses protect wires. If the expected current is 300amps the wires and class T fuse is for 125% of that

300a * 1.25 = 375amps.

Pick your wire type and look it up. Just realized the places the wire attaches need to take the heat rating otherwise we would all just use 200c wire. I usually use the 60c table for sizing and buy 90c or 1035c wire.

 

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