Fuse between battery and shut off switch?
- Thread starter pda1
- Start date
windsurfer
New Member
- Joined
- Nov 4, 2022
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- 40
Yes
Dave911
Solar Enthusiast
It depends.
How big is the cable from the battery to the switch?
How big is the cable from the switch to your Victron device?
Where is all of this located?
What battery are you using? Does it have a built in fuse?
How long are these cables?
Are they exposed to possible damage?
How big is the cable from the battery to the switch?
How big is the cable from the switch to your Victron device?
Where is all of this located?
What battery are you using? Does it have a built in fuse?
How long are these cables?
Are they exposed to possible damage?
TM48
New Member
The fuse should be as close to the battery as is practicable.
Ok. I'll keep it that way. Mine's about that close also.
robbob2112
Doing more research, mosty harmless
If the battery doesn't have a built in fuse of breaker -
A MRBF fuse of the appropriate size mounted on the battery terminal. The correct size is 20% higher than the rated output of the BMS. The wire should also be sized to 20% higher than the BMS can put out.
IF the distance from the battery to the cut-off switch is more than a foot or so it would be good to add a second MRBF at the input to the cutoff. This is in case there is a short someplace along the cable.
With multiple batteries in parallel this is more important. And if you have 3 or more in parallel you may want to consider class T fuses.
The MRBF requires a mounting block as does the class T. The reason for these is they have a higher AIC than the Mega and ANL style fuse and lower resistance so they generate less heat.
Don't trust amazon for fuses, to many fakes - stick to Del City or mouser for the MRBF and you can get the class T from amazon IF they are Littlefuse, Bussman, Eaton, or Blue Sea Systems (relabeled, made by the other 3)
Also make sure to use no-ox-id special or equivalent on all mating surfaces - it makes for a better connection and inhibits corrosion.
A MRBF fuse of the appropriate size mounted on the battery terminal. The correct size is 20% higher than the rated output of the BMS. The wire should also be sized to 20% higher than the BMS can put out.
IF the distance from the battery to the cut-off switch is more than a foot or so it would be good to add a second MRBF at the input to the cutoff. This is in case there is a short someplace along the cable.
With multiple batteries in parallel this is more important. And if you have 3 or more in parallel you may want to consider class T fuses.
The MRBF requires a mounting block as does the class T. The reason for these is they have a higher AIC than the Mega and ANL style fuse and lower resistance so they generate less heat.
Don't trust amazon for fuses, to many fakes - stick to Del City or mouser for the MRBF and you can get the class T from amazon IF they are Littlefuse, Bussman, Eaton, or Blue Sea Systems (relabeled, made by the other 3)
Also make sure to use no-ox-id special or equivalent on all mating surfaces - it makes for a better connection and inhibits corrosion.
robbob2112
Doing more research, mosty harmless
Give me more details or a diagram and I can be more specific. Your current diagram shows the switch bolted to the end of the bus bar verse into the side of the Lynx. There are Mega fuses slots inside the Lynx, use the 70v version. If you connect to those with your battery you only need a MRBF on the battery post if your cables are longer than a foot or so.
Is the idea to put a MRBF on the positive terminal of the battery? I think I'll do that.
When you read the words below, this is how my system presently is. I haven't installed the Lynx Distributor yet.
Like the diagram above, presently I have a Blue Sea fuse holder with a 100a mega fuse (#2 welding wire). The fuse holder is connected to the battery positive terminal but a piece of #2 wire about 7" long.
When you read the words below, this is how my system presently is. I haven't installed the Lynx Distributor yet.
Like the diagram above, presently I have a Blue Sea fuse holder with a 100a mega fuse (#2 welding wire). The fuse holder is connected to the battery positive terminal but a piece of #2 wire about 7" long.
robbob2112
Doing more research, mosty harmless
Del city has good prices on MRBF holder and fuses.
Oh, get rubber boots for your wires, the larger size will fit over the MRBF.
Oh, get rubber boots for your wires, the larger size will fit over the MRBF.
MRBF will save from have another fuse holder and crimps. Great idea....thanks.
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