fuse selection for small 12v system

[saltmarsh]

components so far:

12v 100ah mini lifepo4 battery with bms (power queen)
250 rich solar panel
Victron 7515 charge controller

I bought an inline 15a mc4 fuse to go between the single Rich solar 250w panel and the 7515 charge controller. It seems like this inline fuse should be close to the panel. I'm assuming outdoors is fine (Tiny house)?

This system is only for small and/or small continuous loads. The most immediate use for this system is a 2.5 watt fan for a Separett Villa toilet. The company includes a dc specific power cord with an inline fuse and battery clips. Can I can clip this directly onto the battery and not worry about another fuse?

Itdoes seem like I may need a fuse between the charge controller and the battery. And that it should be slightly larger than the charge controller amperage. So a 20A anl fuse? Is this one appropriate?:

20A/30A/40A/60A/100A/200A/300A/400A ANL Fuse Set w/ Fuse

Renogy 20A MC4 Solar ANL Fuse Holder Waterproof w/ Fuse is Gold/Nickel plated terminal contact for corrosion resistance. The Renogy ANL fuse will protect the charge controller, wire, and battery from over-current. Free shipping!

www.renogy.com

Also, what if I want to add other small loads? I'm thinking of a charging port hub for usb devices and laptops. I'm unclear whether to get a bolt on fuse holder or a fuse block? And would I then need still be ok attaching the fan with the clips?

Thanks for any suggstions!

 

[Hiker]

I'm pretty sure the most watts you get from that controller is 220W but in decent sun you should hit that figure quite often. I have the same controller with two 100w panels and hit it often. I don't have an inline fuse between panels and controller but do have a 20amp DC breaker. I also have a six circuit fuse block (100amps total). A 80amp MEGA/AMG fuse at the positive battery terminal, and a 60amp break to shut the "portable system" down.

 

[saltmarsh]

Wow thank you so much for this photo, it’s making everything more understandable!

A breaker instead of a fuse I may dip in to ask some clarifying questions later ?

 

[Hiker]

Wow thank you so much for this photo, it’s making everything more understandable!

A breaker instead of a fuse I may dip in to ask some clarifying questions later ?

Sure. I did quite a bit of research for the project, watch lots of videos by Will and Nate from explorerlife.

Although the panels alone have kept the battery charged, I'll be adding a Orion DC/DC charger filling the last circuit in the fuse block. For AC (also DC/USB) I have a Ecoflow Delta Mini which can be charged using the XT60 (or I have a dedicated circuit when my minivan is running). The barrel plug runs a 12v TV, the 12v receptacle a car fridge, the powerpole plug porch/interior lighting and a USB fitted outside under the mounted panels. It's amazing, also charging phones, tablet, ebike batteries, I've never run out of juice or needed shore power.

I can give you a list of parts I used, mostly bought off of Amazon. Mostly cheap, they seem to be holding up.

 

[Dave in AZ]

@Hiker neat build. What is going on with the mppt output wire? You take solar, to mppt, then from there to a fuse on fuseblock? and then on to the battery? Then battery goes back and feeds the fuseblock bus? I thiink I see you're just using the fuseblock busbar to feed the battery, instead of connecting to a battery busbar outside of the fuseblock, with an inline fuse to protect the mppt supply wire? But then I see another small wire from same dc fuseblock spot that looks like it goes to battery... just confusing me there. Thx!

 

[Hiker]

@Hiker neat build. What is going on with the mppt output wire? You take solar, to mppt, then from there to a fuse on fuseblock? and then on to the battery? Then battery goes back and feeds the fuseblock bus? I thiink I see you're just using the fuseblock busbar to feed the battery, instead of connecting to a battery busbar outside of the fuseblock, with an inline fuse to protect the mppt supply wire? But then I see another small wire from same dc fuseblock spot that looks like it goes to battery... just confusing me there. Thx!

I suppose you could call it the poor man's Lynx Distributor. The battery attaches to the +/- main terminal of the fuse block with the 6AWG wire and is fed by the controller with a 20A fuse. Under that feed is the circuit to the switched 12v/USB gizmo (through a hole in the wood panel). Since I don't have an AC inverter attached, I don't think I really need any busbars, etc. and I'm not that worried about it. It ran six months straight without any problems whatsoever. No tripped breakers or blown fuses. It's worked great for a bunch of 12v/USB devices.

I'll be adding a Orion 12|12 18A charger but I'm moving one of the lesser draw circuits from the left to the right, placing the Orion circuit on the left to balance it out. Total fuses will add up to 95A but in reality if I was using all the circuits at once it would be under 60A total.

To be honest I'm still not sure of how amps in/out actually works. I know if the two chargers are pumping 33A in (max), and I'm using about 20A out, it's a net gain.

I've attached another image with the fuse block cover off and a little better view. Moving circuits around a bit to add the Orion this weekend.

 

[Dave in AZ]

I suppose you could call it the poor man's Lynx Distributor. The battery attaches to the +/- main terminal of the fuse block with the 6AWG wire and is fed by the controller with a 20A fuse. Under that feed is the circuit to the switched 12v/USB gizmo (through a hole in the wood panel). Since I don't have an AC inverter attached, I don't think I really need any busbars, etc. and I'm not that worried about it. It ran six months straight without any problems whatsoever. No tripped breakers or blown fuses. It's worked great for a bunch of 12v/USB devices.

I'll be adding a Orion 12|12 18A charger but I'm moving one of the lesser draw circuits from the left to the right, placing the Orion circuit on the left to balance it out. Total fuses will add up to 95A but in reality if I was using all the circuits at once it would be under 60A total.

To be honest I'm still not sure of how amps in/out actually works. I know if the two chargers are pumping 33A in (max), and I'm using about 20A out, it's a net gain.

I've attached another image with the fuse block cover off and a little better view. Moving circuits around a bit to add the Orion this weekend.View attachment 187164

Thx for the kind reply. I really like your 2 sided system, it's quite clever. I just hadn't considered using the dc fuseblock to feed power to the battery, guess I was thinking too linearly!