Victron Energy: Alternator/Solar Charging - LFP Battery System

Photobug

Active member
Looking at fuses, I'm going to save some space with a Blue Sea 300A MRBF terminal fuse on a single terminal fuse block. The max discharge rate of the battery is 320A, so this will function as a last ditch protective measure, with a little headroom.

View attachment 545480
Those are great, I am using one on my current build. It saved some pain when i dropped the wrench across the battery terminals before. They also make a double MRBF if you wanted to run two sized wires off the battery.
 

shade

Well-known member
Those are great, I am using one on my current build. It saved some pain when i dropped the wrench across the battery terminals before. They also make a double MRBF if you wanted to run two sized wires off the battery.
Thanks for the double-tip. I might want to do that so I have the charge sources on one lug, and the load on the other.

1571437002966.png

I'm using this PKYS blog entry as a guide for getting all of the bits together.

Edit: Actually, the PKYS guy uses the terminal block. Hard to see in the tiny photos.
 
Last edited:

Photobug

Active member
The guy sticks one of those fuses directly on a battery terminal, which is warned against by Blue Sea, but otherwise his project looks ok.
Not sure why Blue Sky warns against this, as far as i know it is how things are done or at least was done when I wired a boat in 2016. Maybe something happened once since then that caused them to issue a CYA warning against such use. Without the option to place a heavy-duty fuse in the same area as the battery terminal this item loses some of its charms.
 

shade

Well-known member
Not sure why Blue Sky warns against this, as far as i know it is how things are done or at least was done when I wired a boat in 2016. Maybe something happened once since then that caused them to issue a CYA warning against such use. Without the option to place a heavy-duty fuse in the same area as the battery terminal this item loses some of its charms.
I'm not sure. It may have been due to an oddball fault, or a more recent concern. They're produced for the marine environment, which as you know is as corrosive as it gets for this kind of thing. Add in some sloshing electrolyte, and maybe it's possible for corrosion on the battery terminal to allow a path to develop around the fuse.

"Space-saving ignition protected fuse for 30 to 300 Amp loads. Must use with Terminal Fuse Block." 🤷‍♀️
 
Last edited:

luthj

Engineer In Residence
Could be vibration causing battery cracking. Could be heat dissipation issues.
 
Last edited:

shade

Well-known member
If it's been common practice in the past, a fault related to use over time would make sense. Beats me, but if the Blue Sea folks want it that way, they probably have decided that's how best to use those fuses and stay within code. One failure on a boat could change how they're used, especially if it caused a fire, or loss of a critical system.
 

shade

Well-known member
Ha ha !
Guys, read that again...
I am english secondary, and even I understood right off the hop..
”Must use with Terminal Fuse Block”. That link is a catalogue page for fuse cartriges. Their comment means use it with the appropriate terminal fuseblock/fuseholder for that device.
I know. The issue is that those fuse cartridges have apparently been mounted directly to battery terminals in the past, not a fuse block. Blue Sea recommends otherwise.
 

shade

Well-known member
Question: Should a manual disconnect switch be placed between the panel & solar charge controller, or the charge controller & battery?

I'm thinking it should be between the panel & charge controller, so if the panel is disconnected for servicing, the charge controller isn't getting power pumped into it from the panel.
 

shade

Well-known member
Wow !!
That would be a creative and tedious assembly of insulating sleeves.
Or, just use a non conductive bolt...Otherwise the fuse would never be in the circuit.
Hard to believe somebody could be that ignorant ?? But maybe not...
I'm not sure. Maybe the Blue Sea advisory was added just to direct people to the correct fuse block for the item, but it seemed more like a warning since they usually have links to associated items at the bottom of the page.
 

Alloy

Active member
If nothing more a battery should be enclosed in a battery box, if in a vehicle, for protection against battery acid spills. The box and battery should also be strapped down to prevent being overturned.
I'll use plastic battery boxes but I drill holes in the bottom of the box.....seen too many batteries submerged in water
 

shade

Well-known member
Sorry, V. Your post was too hashed up to quote.

If I want to service the solar panel, charge controller, or wiring in that circuit, I think it would be more convenient to have a switch in place to disconnect power than have to disconnect a wire in the circuit. I've read that allowing a panel to continue sending power to a solar charge controller without having the controller connected to a battery can damage the controller, but I've also read that it's not a problem.
 

shade

Well-known member
I'll use plastic battery boxes but I drill holes in the bottom of the box.....seen too many batteries submerged in water
I had to do that to an external battery box on a camper. The lid vents allowed rainwater in, which wasn't so great.
 

Alloy

Active member
Question: Should a manual disconnect switch be placed between the panel & solar charge controller, or the charge controller & battery?
I use switching breakers on the input and output. These protect the wire and will disconnect the power so the controller can be removed whithout shutting the system down.
 
Top