Roast my first build for off grid cabin

[TechnoTime]

Project still underway, but I figured I share some pics in case there is some fatal error and you guys might save the cabin.

Gonna be small system, 12 volt DIY China special LiFePo4 (200ah), 2x300w panels.

Worst part is that we get cold winters here and electric "box" is attached to outside wall of cabin. I've insulated it quite a bit + there will be small shed protecting it (worried about condensation). I plan to wire up 2x20w silicone heating pads to batteries chamber that will activate if it gets too close to freezing and only if it's daylight hours (using time switch) on order not to waste energy heating it up at night.






Built an adjustable ground stand with leftover wood (still needs paint job)





Added easlily adjustable fixator on both side for 3 positions (summer, winter, spring / fall)



Gonna try to finish it up in a week or so. Almost everything is aliexpress, and cost for everything is around 1300 USD.

Roast away!

 

[Charleswgibbs]

I'm curious to see how much power you are able to pull from that 3000w inverter, it's not much bigger than an old 400w xantrex I've got

 

[Wjm1964]

In no way a criticism, but the 250A breaker for the inverter will throttle the current, maybe consider a mega or ANL fuse? Also heat is what kills inverters, i personally would mount it vertically so heat escapes easier & don't over tighten the screws that mount the inverter, allow some small movement - it will expand slightly as it heats up. I leave a little play.

 

[Will Prowse]

That inverter looks awfully small to have a output capacity of 3000W. Do you have a link of the product page or data sheet?

Does not look that bad. I think the weakest link is the circuit breakers. Good choice in fuse block and bus bars.

 

[wiseacre]

I like the mount, similar to mine it uses a bolt for the swivel

 

[TechnoTime]

Oh please criticize! I'm a noob (I don't even know what mega or ANL fuse is).
All the lights / USB charging ports in cabin gonna run with 12v DC and inverter gonna be mostly turned off and turned on if there's a real need for 230v. It's a 1500w intverter btw (3kw surge). I honestly expect it to tap out somewhat quick from humidity.
Inverter link - here's the link to it.

Btw Will, your videos are what encouraged me to even attempt something like this!

 

[CoolWill]

I know everyone likes the bells and whistles approach using equipment specialized for the use, but I often think in terms of reliability, replaceability, and cost. In that regard, a household heater thermostat is crazy reliable and dirt cheap at any hardware store. Automotive incandescent brake light bulbs are plentiful and dirt cheap. A simple thermostat connected to a brake lamp would be so effective and reliable as a battery box heater.

 

[TechnoTime]

I know everyone likes the bells and whistles approach using equipment specialized for the use, but I often think in terms of reliability, replaceability, and cost. In that regard, a household heater thermostat is crazy reliable and dirt cheap at any hardware store. Automotive incandescent brake light bulbs are plentiful and dirt cheap. A simple thermostat connected to a brake lamp would be so effective and reliable as a battery box heater.

Would the brake lamp be enough for heating? I have a thermostat there (3$), and silicone pads are also just 3$ each, so can't get anything much cheaper than that.. Reliability is what could be improved. I haven't tested my heating system yet, quite curious if it actually gonna work.

 

[CoolWill]

Would the brake lamp be enough for heating? I have a thermostat there (3$), and silicone pads are also just 3$ each, so can't get anything much cheaper than that.. Reliability is what could be improved. I haven't tested my heating system yet, quite curious if it actually gonna work.

I suppose that's pretty cheap! I don't know how insulated the box is nor how cold it might get in your location. So I don't know if one lamp would cut it or not. But mostly I was speaking in general about simple heating.

 

[Mattb4]

Be sure to monitor components for heat during loading. You would not want any fires. It would help to have a fire extiguisher always availble. You would likely have to keep it indoors due to freezing weather but next to your entry door would not be a bad idea.

 

[TechnoTime]

Be sure to monitor components for heat during loading. You would not want any fires. It would help to have a fire extiguisher always availble. You would likely have to keep it indoors due to freezing weather but next to your entry door would not be a bad idea.

Fire would suck. I've insulated my box with rock wool and foil in hopes it'll contain the fire if there is any.. It's off grid sauna cabin that will be used just on weekends mostly. Should I consider shutting down the whole system if I know that nobody's gonna be around for several days?

 

[TechnoTime]

I suppose that's pretty cheap! I don't know how insulated the box is nor how cold it might get in your location. So I don't know if one lamp would cut it or not. But mostly I was speaking in general about simple heating.

Gotcha. I'm in Northern-ish Europe, so winter usually is -5 to -10 Celsius, but sometimes goes down to -20.

 

[CoolWill]

Fire extinguisher balls come to mind for remote systems. They just sit there waiting for fire and self activate if needed. Elide and others make them pretty affordably.

 

[Mattb4]

Fire would suck. I've insulated my box with rock wool and foil in hopes it'll contain the fire if there is any.. It's off grid sauna cabin that will be used just on weekends mostly. Should I consider shutting down the whole system if I know that nobody's gonna be around for several days?

Until you have some experience with how it is working I would suggest not leaving it energized and un-monitored.

 

[danmc]

That inverter looks awfully small to have a output capacity of 3000W. Do you have a link of the product page or data sheet?

Does not look that bad. I think the weakest link is the circuit breakers. Good choice in fuse block and bus bars.

Looks like this one: https://www.ebay.com/itm/133815446248

Peak power 3000W
Continuous power 1500W

 

[Mattb4]

Fire extinguisher balls come to mind for remote systems. They just sit there waiting for fire and self activate if needed. Elide and others make them pretty affordably.

Thanks. I had never heard of them before. I see they are available on Amazon.

Fun to find new things.

 

[TechnoTime]

Fire extinguisher balls come to mind for remote systems. They just sit there waiting for fire and self activate if needed. Elide and others make them pretty affordably.

This seems like exactly what I'd need!

https://www.aliexpress.com/item/1005002226494368 - roughly 30$ with shipping. I'll order 2 of those and put one in each compartment. Only concern would be it activating from heating pads, but it shouldn't happen.

 

[TechnoTime]

Small victory today!

Finished wiring everything except grounding and panels, and all the lights and power sockets are working as they are supposed to! I'm quite relieved as I did all the wiring for the cabing myself and burried all the wires deep inside walls. Tried to run 900w angle grinder from power sockets and it worked.






2



This indicator light means that the fuse is blown (or there is none as in this case)? If I pull all the fuses, only 2 indicator lights turn on so idk what to think of it.

 

[Mattb4]

Congratulations!

Do not know how your fuse block is setup but it is possible that it would only indicate a blown fuse if the fuse above/below it is functional. With no fuses all it indicates is the first two as bad.

 

[TechnoTime]

Aaaand we are up and running! Launch went smoothly! I have 2x300w panels in series and was pulling in 470w (clear-ish sky), which is good enough.

When connected to SCC via wifi app, I came up to this setting - "Low temperature prohibits discharge temperature" which is at 0 °C by default. Is there a reason for it? I need my battery to discharge below that to initiate heating, and as far as I know, there's no damage to LiFePo4 doing so, therefore I should just edit it to -50 or whatever I guess.