Wires/fuses from main battery switch to busbars

[LifesBetterWhenYoureBeating]

Hi there!

I'm rearranging the electrical connections going into my house battery, partly to tidy them up and partly to help me identify/fix potential issues (mainly wire sizes and missing fuses). Since the PO left me a couple MRBF surface mount blocks (https://www.defender.com/product.jsp?id=4420329) and a bunch of mrbf fuses, I'd rather use them instead of inline fuses if possible.

In this case I'm using one block between my main battery switch and a couple busbars, and I'm doing that because the battery post has a 200A MRBF fuse but my busbars are rated for 150A (which is enough for my accessories), so the fuses in the mrbf block will protect my busbars (and the smaller wires that connect them to the fuse block itself). From the busbars all the positive wires are also fused.

The attached photo shows how everything is wired. One small issue that I've already identified is the fact that my fuses are in series so in case of a short it won't be immediately clear on which exact wire it happened, but I think that's something I can live with. I also considered connecting the 3 upper posts on the block (making it the same as the common source fuse block from BlueSea, but that'd require me to use 200A rated wires on the jumpers and it'd be hard to fit them there). Can anybody se any other issues with this setup? Or any ways to simplify it

Thanks in advance

[goboatingnow]

Originally Posted by gsalgado

Hi there!

I'm rearranging the electrical connections going into my house battery, partly to tidy them up and partly to help me identify/fix potential issues (mainly wire sizes and missing fuses). Since the PO left me a couple MRBF surface mount blocks (https://www.defender.com/product.jsp?id=4420329) and a bunch of mrbf fuses, I'd rather use them instead of inline fuses if possible.

In this case I'm using one block between my main battery switch and a couple busbars, and I'm doing that because the battery post has a 200A MRBF fuse but my busbars are rated for 150A (which is enough for my accessories), so the fuses in the mrbf block will protect my busbars (and the smaller wires that connect them to the fuse block itself). From the busbars all the positive wires are also fused.

The attached photo shows how everything is wired. One small issue that I've already identified is the fact that my fuses are in series so in case of a short it won't be immediately clear on which exact wire it happened, but I think that's something I can live with. I also considered connecting the 3 upper posts on the block (making it the same as the common source fuse block from BlueSea, but that'd require me to use 200A rated wires on the jumpers and it'd be hard to fit them there). Can anybody se any other issues with this setup? Or any ways to simplify it

Thanks in advanceAttachment 265207

Why are U arranging them in series. A downstream 50A behind another 50Α doesn’t make a lot of sense.

[LifesBetterWhenYoureBeating]

Originally Posted by goboatingnow

Why are U arranging them in series. A downstream 50A behind another 50Α doesn’t make a lot of sense.

That allows me to use a smaller jumper wire on the fuse block. If I were to connect the 3 upper posts I'd need 200A rated wire

[Kelkara]

This looks really confused ...

It looks like you should just replace the fuse at the battery with a 50A fuse, then connect the other 3 fuses in parallel on the positive side. Then as long as your combined wind and solar is less than 50A and your maximum load is less than 50A, you should be able to wire everything with wire rated for 50A.

There appears to be no need for a 200A fuse at the battery.

[smac999]

you can't run the solar and wind after the switch. should be direct to battery.

also the fuse jumpers are totally wrong. for one reason if the load wire shorted out and the load fuse blew, the solar would keep putting power into the short and never blow the solar fuse.

if you use a mrbf fuse block they are already all connected on the input side.

https://www.bluesea.com/products/519..._Common_Source

[LifesBetterWhenYoureBeating]

Originally Posted by Kelkara

This looks really confused ...

It looks like you should just replace the fuse at the battery with a 50A fuse, then connect the other 3 fuses in parallel on the positive side. Then as long as your combined wind and solar is less than 50A and your maximum load is less than 50A, you should be able to wire everything with wire rated for 50A.

There appears to be no need for a 200A fuse at the battery.

You are correct, I've no need for a 200A fuse on the battery. I only chose that because the wire going to the switch can handle it, so I thought it'd be better to go with a bigger fuse in case I ever add power hungry loads. It's probably better to go with a smaller fuse for now and change that if I ever need

[LifesBetterWhenYoureBeating]

Originally Posted by smac999

you can't run the solar and wind after the switch. should be direct to battery.

also the fuse jumpers are totally wrong. for one reason if the load wire shorted out and the load fuse blew, the solar would keep putting power into the short and never blow the solar fuse.

if you use a mrbf fuse block they are already all connected on the input side.

https://www.bluesea.com/products/519..._Common_Source

Why must the solar and wind go directly to battery? I want them before the switch so I can direct them to my starter battery as well

[smac999]

Originally Posted by gsalgado

Why must the solar and wind go directly to battery? I want them before the switch so I can direct them to my starter battery as well

what happens when you turn that switch off and your house draw is 15a and the solar charge is 10? everything is going to hell. you can't power loads direct from a charge source.

chargers are never switched. if they are, they need their own switch so they can't feed a load.

there is no reason to charge an engine battery that gets run every so often

[NPCampbell]

Originally Posted by gsalgado

That allows me to use a smaller jumper wire on the fuse block. If I were to connect the 3 upper posts I'd need 200A rated wire

I'm not understanding this. If you put fuses in series 1) it doesn't increase the amount of current it will take before blowing and 2) you have to play a guessing game when a fuse blows. Which device was the cause? The first device in the chain or one downstream?

[JimsCAL]

Actually a fuse at the battery is a good idea. Read this article on the subject.
https://marinehowto.com/battery-bank...nt-protection/

[Kelkara]

Originally Posted by JimsCAL

Actually a fuse at the battery is a good idea. Read this article on the subject.
https://marinehowto.com/battery-bank...nt-protection/

I hope I didn't give the impression that the fuse at thde battery wasn't required ... just that a 50A fuse would solve his problem of not wanting to install wires rated for 200A.