Wires and fuses. Please help me to make sure nothing goes up in flames.

Levo

Alberta Glamper
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Dec 4, 2021
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74
Location
Western Canada
Okay you have at least given me a path forward and saved me from "barking up the wrong tree". Shall take a closer look at the waytek products and re-inspect all the joinery. I appreciate your time and know how.
 
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after1985

New Member
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Apr 5, 2022
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But, after mounting the Littelfuse 175A (yes, I know MRBF is better) at the battery terminal, significant heating occurred in 5 minutes or so, right at the fuse location and slightly on the wiring.

I was very careful with fuse mounting, solid copper (polished, 3/16" x 1" flatbar), clamped very tightly, but there is apparently significant resistance there.

I understand that single 2AWG should be good up to 180A continuous current. Given that the heating occurs right at/around the fuse, would the heating be reduced/eliminated by upping the wire size, or is there something else I am missing regarding the fuse assembly? As indicated, all stayed cool without the fuse. If wire upsizing is the only solution okay, but would hate all that work and (some) expense if it is not really the problem. Thanks.

I have a similar issue, and it might help you with the wiring question. I have a 100AH battery, 4/0 wiring, a 3000W inverter. When I draw around 130A, my MBRF terminal fuse and terminal get really hot to the touch. Nothing else in the system gets even warm. I think these style fuses must have a ton of resistance. I have a victron lynx distributor "busbar" and the MEGA fuses there do not get hot. So if mine is getting hot with 4/0 wiring, I don't think it'll help you.

I like having the fuse right at the terminal, but after reading your issue I'm not so sure it's going to work long term for me.
 

after1985

New Member
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Apr 5, 2022
Messages
20
Is your fuse mounted in the Bluesea carrier?
Do you have an IR thermometer or camera?

No IR cam, but it's mounted in the Bluesea carrier directly onto the battery terminal with the included M8 bolt. On top of the fuse is the 4/0 ring terminal (pure copper) and then the 4/0 cable.
 
Joined
Nov 30, 2019
Messages
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No IR cam, but it's mounted in the Bluesea carrier directly onto the battery terminal with the included M8 bolt. On top of the fuse is the 4/0 ring terminal (pure copper) and then the 4/0 cable.
Should be good.
Have you considered contacting Bluesea?
 
Joined
Nov 30, 2019
Messages
12,199
No IR cam, but it's mounted in the Bluesea carrier directly onto the battery terminal with the included M8 bolt. On top of the fuse is the 4/0 ring terminal (pure copper) and then the 4/0 cable.
Why do you have a 4/0 cable and a 3000 watt inverter(presumably at 12 volts) connected to a battery that can only deliver 100 amps continous?
Also MRBF fuses only go to 300 amps?
Perhaps you have multiple batteries?
 

Levo

Alberta Glamper
Joined
Dec 4, 2021
Messages
74
Location
Western Canada
Okay you have at least given me a path forward and saved me from "barking up the wrong tree". Shall take a closer look at the waytek products and re-inspect all the joinery. I appreciate your time and know how.
All the joinery is now as good as I know how to make it. All mating faces, (including the fuse) polished with 1500 and solvent cleaned. I even removed the tiny burrs around mounting holes in the fuse and lug. Re-sized the insulated bolt to M8. As I had a 200A fuse, decided to up that to avoid nuisance pops.

Joey, the improvements proved your mantra "joinery, joinery, joinery" is worth heeding. After 15 minutes drawing 148A the assembly was "warm" to the touch but much less than previously and no warmer after 30 minutes. I may buy an IR thermometer to quantify and trend the temperature.

I think I am out of the woods on this as the heater was just for the test. Highest actual use will be a 900w microwave (1350w draw max 10 min) and compressor fridge (172w) with usage overlapping for maybe a few minutes at a time.

Decided to stick with my own fuse mount as Blue Sea and Zcase products mount on M10 studs. My battery terminal only accommodates M6 bolt, so fits precisely. Also I can't see how they would perform any better than a solid copper plate.
 

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