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Small Cabin Forum / Off-Grid Living / New Mini Solar System
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# Posted: 16 Sep 2023 21:33

A new friend just gifted me his RV solar system. It didnt work out like he had hoped for their RV and has been sitting on a shelf for a good while. When he found out about our off grid cabin he asked if I was interested...well, Yeah!
2x 100w panels c/w his diy pvc mount set up
PWM scc, 30a
Cabling, MC4 con's and output lead c/w an Anderson con.
My LFP bats have the Andersons, so I carried one out to the front yard, it was a quick & easy plug & play. All I really had to do was find a couple 3' pipes to brace into the pvc sockets to orient the 'array' toward the mid-day sun. Within minutes I was charging; Too Easy.
These panels are about 1/2 the size of my old 100w units, and far lighter; truly a portable system imo.
It will be way easy to make a simple post and 2x4 ground mount to set them into somewhere 'out of main view' and carry an LFP over to charge while we are there. I can rotate our 2x 100ah bats to good effect.
One option, but not the best orientation (pretty much E) is to mount them on the wall of my toolshed either side of the window, kind of a 'shutter' look.
Yep, back to messing about with solar, lol

# Posted: 17 Sep 2023 09:00

Nice gift!

# Posted: 17 Sep 2023 11:04

Free is good. Nice score.

# Posted: 17 Sep 2023 14:01 - Edited by: gcrank1

A nice thing about LFP is it doesnt need to be recharged asap to prevent sulfating like lead acid does.
This means that a smaller array can pump in some amps/watts at my convenience whereas the LA needed to have the big array to hopefully recharge by mid-day after a night's use.
We havent done much at the cabin for the last 5wks+ since my accident so the LFP has just been sitting inside unused. NO worries about its state of charge or self discharge, no checking water levels or SG.
Too Easy

# Posted: 20 Sep 2023 10:18 - Edited by: paulz

Been keeping a closer eye on my LFPs too. Days are getting shorter and cloudier, been living in the cabin 6 days a week for last two months, and watch a movie on the big screen most nights. I have a generator charger if needed but try to keep them above 13 volts (12 v batts) as I read somewhere that 13.0 is 50%. Nice to hear that further discharge won’t hurt them.

# Posted: 20 Sep 2023 10:28 - Edited by: gcrank1

Your 'short cycling' them is good, just like with LA. It shows you have a big enough bat bank to not need to go deep into the SOC.
Ive gone to 12.8 but with the sag (and depth of sag dependent upon load) it can quickly go into the Low Volt Discon. Plenty good even there for just running LeD lights and USB chargers though.
Im using the Meanwell Power Supply set (Note: only set it under No Load) at 13.8v and watch it Very Carefully for when it 'tops out' to the Amps falling off. Once it drops to about 5a on my cheap old inline meter I shut the PS down; ie, Do Not leave it going to 'absorb' like we used to with LA (they needed it, LFP can be damaged/life shortened).
Doing it this way is supposed to get me 95ish % and be totally good to the bats.
The bats will 'settle' to 13.3-13.4ish relatively quickly or with just a little use. No Worries, that is Right On.
Also watch for a voltage drop from the PS to the bat terminals. My leads are short and only an Anderson con between which is min. additional resistance. Tweak the PS to get that 13.8 delivered at the bat.

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