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gcrank1
Member
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# Posted: 17 Jan 2021 06:09pm - Edited by: gcrank1
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My place has a modest system, I imagine not too different that what a lot of cabin/cottage/bigger rv folks have or think they would like to have.
Im limping along with old 12v lead acid bats from the system at the place we bought this past Aug 2020.
It had 4 x 125+ah ups type sealed bats (as of last fall Im down to 2 in parallel).He had all 4 in parallel with the cc cables at one end of the string and the pwr out (both 12vdc and a 1000w 120vac inverter) at the other end. Not supposed to be a good way to do it but it looks like this all lasted since 2012ish.
It is basically a 3 season place but we have been going so far this winter about 1x wk for an afternoon or short day so it is min. use of elec. That could end any snow now.
They are charging off solar in our absence on 4x 102w panels in a 2s/2p array (for 24v) into a Blue Sky Solar Boost 50 mppt cc. I have 2 more panels to make 2s/3p total this next summer. Which is how the orig. set up was that I had to disassemble from roof mount, move and make grd mounts.
So, I think the array size is adequate for us, the cc is correctly sized to the array when fully installed and mppt is the right way to use it all (but Im open to correction and suggestions).
I invert to 120vac at the 'power-house' some 90' from the cabin. The only 12vdc is at the power-house.
I think his original bat-bank of 500ah was sized right to charge well with the above. And I think I understand correctly that it gave a good 125ish ah useable power (25%) with a bit more occasionally but bad for battery health.
My first inclination has been to go with 4x GC 6v, 2s/2p for about 450ah @ 12v. This would emulate his orig bat-bank with what I think are more suitable deep cycle batteries.
But, if Ive got this figured right, a LFP battery of about 160ah min. with some 80% of that usable on a regular basis should perform at least as well and last lots longer. 200ah LFP would be a nice upgrade in ah's available. It would be nice also to have included bms to avoid overcharging, etc and if I can use my existing BS cc (EQ is currently turned off and iirc bulk and absorb are 'tunable').
Would it make sense to use, say, 2x 100ah LFP's in parallel so if one goes bad I can still run?
So, knowing we pretty much get what we pay for but not wanting to overpay when I dont have to.....
1) should I stick with the GC bats for now and let the LFP thing sort out and prices maybe come down?
2) or specifically what LFP battery(s) should I be looking at to get the most bang for my retired guy fixed income bucks?
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SCSJeff
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# Posted: 17 Jan 2021 08:00pm
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OK, I'll take a stab 
(4) GC batts (assuming regular FLAs) will cost at a minimum $400 for the cheap (but OK) Costco batteries.
Two LifePo4 batteries I've been looking at are: SOK and ReBel. Both have low temp disconnect. Both have 100AH versions in the $550 - $570 range. SOK also has a 200AH for $1029
So $400-$500 (or more) for FLAs that you should only discharge 25-40% (depending on what article you read), requires maintenance (at least for FLA), and take much longer to recharge.
Or... roughly $1000 for LifePo4 that you can discharge 80% (and if you go further on occasion, no big deal) and have much faster recharge. Only caveat, it won't charge below freezing...
I myself am going LifePo4 when my (2) GC2's die (or I just get sick of maintaining them)
J
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Brettny
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# Posted: 17 Jan 2021 08:36pm
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Weekend place..FLA
Staying 3 seasons mostly at once...lithium
Run the cost per AH and what real length for life you expect to get out of them. For us even running FLA down to 50% and they only get 500 cycles that would last nearly 10yrs. I would never expect a FLA even in the best conditions to last 10yrs.
Also for a weekend place skip the more pannels and get more batteries, they will have 4-5days to recharge.
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Nobadays
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# Posted: 17 Jan 2021 09:03pm
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GC... if I'm not mistaken your primary residence is close to the cabin and you are there quite often.... not just on the weekends.
I would agree with Jeff, lithium over FLA. The SOK batteries seem to be a good lower cost pre-built battery. Hadn't heard of the ReBel but will be looking into them myself. The low temperature cut-off on the SOK batteries inread are effective so little worry on that front, besides when you leave just shut off the SCC.
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SCSJeff
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# Posted: 17 Jan 2021 09:09pm
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Brett has a pretty strong case there. I'm the perfect example, my GC2's are going on 7 years now. Probably because I've never let them drop below 70% charge and they've always been able to recharge right back up to 100% after I leave.
However, I want more AH now that the cabin is more finished and I have more things going on. This past deer season, I had no sun for the day and my batts never charged back up and I had to run the generator all evening. More batteries requires more space (which I don't have) and more interconnect cables (which also adds up)
Bang for the buck, I may build my own battery bank using 270AH LifePo4 cells. Total cost should be around $550. So for me, it's a no-brainer. That's the same cost as (4) GC2's and better performance. Although, I will have to come up with a solution for the no charging below freezing issue (even if it is to take the battery home with me)
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SCSJeff
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# Posted: 17 Jan 2021 09:21pm
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Just to follow up specific to GC's question:
You could always go BattleBorn too... I bought one last summer. Sort of kicking myself because I bought it before I found out about SOK and more recently ReBel and paid almost twice as much 
But... you can't go wrong with BattleBorn. It's an excellent battery with great customer support and a 10 year warranty. And I can now attest to how quickly it charges compared to my GC2's.
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gcrank1
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# Posted: 17 Jan 2021 09:33pm - Edited by: gcrank1
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It is our 'get away' and close enough to go on a whim.... and we are retired This past season since the close on Aug.1 we went a lot, LOTs of cleanup of a neglected/distressed property. Got it done, all systems refurbed and functional (yet not 'done') for a visit. This next season we expect to be going a lot 'for us', not to be cleaning up somebody else's mess.
I do want to maximize the effectiveness of the existing total avail. array and cc; the bat's are the known weak link and max'ing them to the above would be pretty sweet. More beans than Ive had from the get-go for sure.
Good point on the 'weekend' use and fla's; Ive been replaying that thru my head too, along with due to our age and all how much longer are we going to be doing this. We subscribe to the 'Life is made for living so do what you can as long as you can' philosophy but another 10years might be a stretch for us. LFP would make however many years pretty painless for me, those fla's are Heavy!. Yeah, I know, put em where ya want em to be and leave em alone......
My long suffering wife paled when I said the bat I want is about $1100. When I replied that I wouldnt have to be messing about with batteries anymore she said,"Ive heard That before".
Fwiw, it looks like for there I need to get an initial permit at $350 from the county then $50 to the power company to even come out, give it a look and est. on running grid in 340ish feet (underground only there). No power actually comes with that set of costs just to get an est!
Theres a set of new Costco GC bat's.
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Steve_S
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# Posted: 18 Jan 2021 04:41am - Edited by: Steve_S
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I may be able to assist if you wish. I'm not interested in conflict in case anyone ponders that.
IF interested look at this material here and you can contact me on the site there. I don't furtle around in this forum too much anymore... just semi-lurking. There are many options and possibilities that can be explored and at various price points as well.... I prefer to explain and educate people, unfortunately, some get terribly offended at such, "giving away secrets to making profits".
https://diysolarforum.com/threads/my-diy-off-grid-cabin-setup-in-ontario-canada-24vdc -120vac.1484/
https://diysolarforum.com/threads/status-of-ess-storage-cells-being-purchased-commodi ty-cells.15539/
https://diysolarforum.com/resources/luyuan-tech-basic-lifepo4-guide.151/
https://diysolarforum.com/resources/general-lifepo4-lfp-voltage-to-soc-charts-tables- 12-24-48v.109/
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Brettny
Member
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# Posted: 18 Jan 2021 07:12am
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Wait grid power is 360' away. I dont see solar paying off in the long run.
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FishHog
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# Posted: 18 Jan 2021 08:43am
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Steve, I appreciate the info you share and haven't even seen the other side of your conflict on here in a long time so I wouldn't worry about it too much.
People either pay others to do the work for them, or enjoy the experience learning to do it themselves and save some money at the cost of a lot of time.
Your posts have been very informative. If only shipping to Canada from China on those Lithium cells wasn't so outrageous now, I'd be ordering and building my own.
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Nobadays
Member
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# Posted: 18 Jan 2021 08:48am
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Thanks Steve! Great links as usual!
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Steve_S
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# Posted: 18 Jan 2021 10:47am - Edited by: Steve_S
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Any of the Chinese sites like Alibaba use "guestimators" for shipping and they are lousy to be honest.
If you request a quotation with the number of cells you desire, you may be surprised. We can get DPP (duty, Taxes etc paid) delivered to your door.
As you know, I'm in the Pembroke/Petatawawa zone in Ontario 200km or so from North West Ottawa. Ive been contacted by several DIYS members in this region who are pr have bought these cells... one fellow even picked up 3 BMS' (Charger BMS8T-300) from me along with EVEA200AAANA energy saver contactors (he got a real sweat deal there @ $150 CAD a piece) for the BMS'. Several of us are getting these direct without issues... and before anyone asks, YES I am the Steve_S @ DIYS that rewrote the chargery manuals.
It actually cheaper to Canada than US unless you must have remote delivery (think beyond normal / usual delivery routes. I've had cells Air Freighted (280AH 5.2kg ea) to me now THAT's a DING.
I have a small stock of "spare bits" I am selling off and have access to other things also.
OFF-SIDE: I have access to higher quality cells at excellent prices which the majority of ALI* vendors cannot access through their "brokers". They are not as cheap as some on offer but that's factory matched for ya. They are roughly $160CAD each for 280AH. Plus S&H
Insider Tip:
Chargery Company (BMS MAKER) who's BMS' I use, at present they are BMS8T for 8S 24V battery packs. Jason has taken suggestions & ideas "Listened & Heard" from myself a few others, developed & release the DCC System (Solid State Smart Contactor (think relay) which is now available.
By next month (Feb 2021) the new BMS Family will be released with improved communications like RS232/485/CanBus +with and controllable / adjustable Active Balancer built-in along with other goodness.
ChargeryStore for the Curious (note the certificate is out of whack for the moment)
https://chargerystore.com/
IF ANYONE Is interested in cells, I can recommend Amy Wan @ Luyuan Tech, yes the one with the linked doc in my previous message.
https://szluyuan.en.alibaba.com/
The website is very out of whack and she will be updating it as soon as all new stocks start arriving (beginning this week) but contact her though chat, aks her for a quota on the cells you are interested in and she can give you an accurate price & shipping rate. MENTION That Steve_S of DiySolarForum sent you!
Hope this is of further assistance for those on the hunt.
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gcrank1
Member
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# Posted: 18 Jan 2021 10:47am - Edited by: gcrank1
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Steve, thanx much for posting in, I will peruse the info asap though my purchase wont be until spring.
Brett, my solar came with the place, we didnt pay extra because it was there either. Imagine, a neglected and distressed place, owner had died and the heir couldnt clean it all up to sell or afford to pay someone to do it. Our offer 'as is' was readily accepted and we did the work.
So all I have to buy is decent battery(s).
I expect the $400ish just to get an est. will result in about another $3500 to $5000 installed to a ready to use ped, or maybe into the CB box and simple interior wiring; then it all would have to pass inspection (now get this) on a place that nothing thus far would pass any inspection (opening not a can of worms but a snakepit)
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Steve_S
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# Posted: 18 Jan 2021 12:34pm
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gcrank, You have the gift of time to research, plan and make decisions, this is good. Rushing on anything is always costly.
A point of interest / comparative.
I bought my 8X Rolls Surette S-550's for $375 ish ea in 2015 ($3000.00 + 13% taxes). That gave me 24V/856AH (gross), 428AH net usable.
I installed 2x280AH LFP Packs. providing 560AH total & usable for less than what the Lead cost me.
Then I added an extra 350AH (2x175AH) and with fiddling I have 910AH usable.
I have another 280AH on the way and arriving soon for the final pack for my bank.
1x 24V/280AH. 8 cells, $1100 USD delivered all inclusive.
1 8S BMS decent FET based one $150 USD +/-
Box: whatever you want.
1 300A MRBF fuse $25 USD with bracket.
280AH LFP can output 1C or 280A for one hour.
It can take 140A charge rate. 0.5C.
Charge Time is 1/2 that of Lead !
Hope it helps.
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gcrank1
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# Posted: 18 Jan 2021 04:38pm
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A few questions have come to mind today:
1) do LFPs need to be closely 'matched' by date of mfr and voltage like L/A do? (ie, can another LFP be added in somewhere in the future w/o degrading the bank)
2) when hooked up to the solar cc and charging in the winter does one need to pay attention to the low temp coming and discon/shut down the array input to the cc before the LFP shuts down the battery? I imagine if the bat shuts down it is like disconnecting the bat from the cc first rather than the array first, usually regarded as bad for the cc.
3) am I right in thinking that the potential c1 discharge rate makes the LFPs much better to accommodate the surge/starting loads of some devices?; ie, inverting to 120vac to power, say, a std 'fridge.
4) My Blue Sky 50 is 50a max output and my isc array total is about 21/25a, the mppt will juggle that some but I doubt it will get to that cc 50 max, at least Ive never seen close to that on the display with the L/A bats even when well depleted in need of charge and good charge conditions.
Do LFPs take charge enough better that what I am used to with L/A does not apply?; ie, of a good solar morning would the LFP charge faster/better with my current array and cc without more array, etc.
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Steve_S
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# Posted: 18 Jan 2021 07:05pm
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Quoting: gcrank1 1) do LFPs need to be closely 'matched' by date of mfr and voltage like L/A do? No, LFP is not like lead that way. Voltage matched yes, 12V, 24V etc... It's unwise to mix different chemistries. 2) when hooked up to the solar cc and charging in the winter does one need to pay attention to the low temp coming and discon/shut down the array input to the cc before the LFP shuts down the battery? Most BMS will do a LoTemp shutdown for discharge at -10C and charge shutdown at 0C. Most SCC's can handle a battery disconnect. Some people do setup a relay control to disconnect solar input from the array(s).3) am I right in thinking that the potential c1 discharge rate makes the LFPs much better to accommodate the surge/starting loads of some devices?; ie, inverting to 120vac to power, say, a std 'fridge. They do handle surges quite well, provided the BMS , wiring, fuses/breakers are appropriate.4) My Blue Sky 50 is 50a max output and my isc array total is about 21/25a, the mppt will juggle that some but I doubt it will get to that cc 50 max, at least Ive never seen close to that on the display with the L/A bats even when well depleted in need of charge and good charge conditions. Do LFPs take charge enough better that what I am used to with L/A does not apply?; ie, of a good solar morning would the LFP charge faster/better with my current array and cc without more array, etc. LFP's do charge faster the Lead. But you have to have enough solar power to recharge the battery power consumed. This is highly underestimated by many folks.
Charging is always a sticky issue to compare.
If you have 400AH of lead, you can only use 200AH of it to be within 50%DOD.
If you have 400AH of LFP, you can happily use 360AH to be within the 80% margin (and the primary power curve) to maximize life & cycles.
So replacing 200AH versus 360AH ...
Then you have to think of good sun hours available to you. More battery = More power required to charge within the available sun hours. More Amps going to LFP the better.
100AH LFP battery will take 50A charge, so 2 hours from 0% to 100% SOC very simply. But a 300AH battery will take 150A charge. Mixing two different capacity packs is OK as well, as the BMS can control some things and if properly parallel wired it will all work quite well. There is a bit of fiddly things to consider though.
You have to appreciate, 4x100W/12V panels is not much at all. The lead likely died due to lack of charge over time and poor maintenance as well.
Doing a Ground Mount, preferably adjustable for the seasons can do a alot. 4x300W 60 cell panels can do a a fair bit and be had cheap. Panels have really come down and used one are available too.
Much to ponder & consider.
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gcrank1
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# Posted: 18 Jan 2021 08:03pm
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Lol, Yeah....many Ive talked to are quick to underestimate their usage and over-estimate the solar capacity and recharging rate. The original prev owner system was 6x102w panels wired 2s/3p to the Blue Sky then into the 4x125ah agm usb bats, all simple linked parallel down the line (bad). It was all hacked together and Im surprised the orig bats lasted at all.
I think he had it pretty well balanced in the old-school way; ie, 100ah of battery per 100watts panel + a bit more panel for loses.
2 of those orig. bats once disconnected would fall below 10.5v after a only a few hours and certainly degrading the bank. Junk-gone.
The remaining 2 still would hold fairly well so I parallel them and on redoing the panels made only 4 panels into a 2s/2p array feeding the 2, now old and tired, maybe now 100ah @, 2 bats parallel, so maybe 200ah gross for a max 100 net?
My array can easily become all 6, 2s/3p, 600ish watts before accounting for the typical losses. Sounds like the LFP can easily take that, even more the better for a faster recovery and I planned on adding those last 2 anyway with whatever new bats I get.
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gcrank1
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# Posted: 5 Feb 2021 04:00pm - Edited by: gcrank1
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So, when I see the specs on a pre-built LFP 'battery' and it says 'cylindrical' or 'prismatic' cells what does that mean?
Is one more desirable than the other and if so, why?
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DryCreek
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# Posted: 5 Feb 2021 06:23pm
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"Only caveat, it won't charge below freezing..."
How do people deal with that in an unattended cabin?
1)If you only need power when you are there, no prob, have the battery in heated space.
2)But if you want to keep things working when you aren't there, in an unheated cabin, what do you do? Put the battery/charge controller/inverter in a super insulated closet and hope the waste heat keeps them above freezing?
(this is northern Rockies, high elevation, so it can get pretty cold)
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FishHog
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# Posted: 5 Feb 2021 07:53pm
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You can put temp controlled heating pads in an insulated box and a charge controller that monitors temp and won’t charge if too cold
But you need enough power generation for the heating pads as well
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gcrank1
Member
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# Posted: 5 Feb 2021 08:19pm - Edited by: gcrank1
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With 3 seasons no worries on the cold, I do wonder about the thing I see about home charging that one shouldnt leave them on a charger after full charged. Isnt always hooked up to the cc like that or is the limited charge hours per day a buffer?
As to the cold at my place, as light and easily moveable as the LFP seems to be I think Id just hook the solar up to a FLA (I always seem to have a few around) and bring the LFP home. Take it back warm and fully charged and in the fringe temps I could just hook it up direct inside like a portable power supply and still backed up by the solar FLA.
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Steve_S
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# Posted: 6 Feb 2021 03:53am - Edited by: Steve_S
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Reply with much info to post and it gives me a 403 Permission denied. So OKAY - Fine. Tried 4 times and same shtick but I can post this... go figure.
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gcrank1
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# Posted: 6 Feb 2021 11:00am
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Thanx for trying Steve
Maybe if you link to some appropriate stuff it wont hit the wall here on 'post space'?
My wife says "I research things to death" but I like the research and hate going into things uninformed.
Your stuff has been helpful
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Steve_S
Member
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# Posted: 6 Feb 2021 11:27am
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Another Attempt and final one. If this fails then TFB. You can always come and find me or a 1000 others at DIYSolarFrorum.com
BAH Humbug !
Forbidden
You don't have permission to access this resource.
Additionally, a 403 Forbidden error was encountered while trying to use an ErrorDocument to handle the request.
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gcrank1
Member
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# Posted: 6 Feb 2021 12:03pm
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Well whats with that?
I will visit DIYSolarForum.com
Btw, my forum name is constant where ever I go.
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Steve_S
Member
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# Posted: 6 Feb 2021 12:15pm
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How ODD, I can post a long response in the Trim Topic. Go Figure.
Removed links and everything else and still will not take. I give up, too bad... this is ridiculous.
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gcrank1
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# Posted: 6 Feb 2021 02:17pm - Edited by: gcrank1
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That chart looks like with a 12v LFP battery I could keep the voltage between 12.4 and 13.4 and be in the sweet zone. Im used to that, I try not to go below about 12.4 (rested dod voltage) on my FLA.
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gcrank1
Member
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# Posted: 8 Feb 2021 10:48am - Edited by: gcrank1
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Any comments regarding the:
Renogy Wanderer Li, PWM, 30A, 12V scc with a new 12V LFP battery (strongly expecting it to be a 100ah)
I still have 1 pair of 102w, 12v, 7.2 a Isc panels Ive been considering making into a moveable parallel array with quick connects for scc and battery (so I dont have to leave them hooked up in my absence).
Thinking if I have the LFP in cabin for overnight I can carry it out come morning, hook it up and let it recharge during the day (my cabin is not well sun exposed for a close array, best location is some 60-75yds away). And rather than run the inverter out there and 120vac to cabin I can just carry/wheel the considerable lighter LFP back and hook it up inside.
Btw, I did similar end of last summer with Grp 27 Marine bat's, swapping out two, but those are HEAVY.
My other 4 panels (same) are wired 2s/2p for 24v into the mppt scc at my ice shanty/now powerhouse & toolshed. I figure to leave that in place for now (well, spring access) hooked up to and for the FLA/AGM still functioning. They like the 'top-up trickle' every day anyway.
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redwolfguild
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# Posted: 8 Feb 2021 06:59pm - Edited by: redwolfguild
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Quoting: Brettny For us even running FLA down to 50% and they only get 500 cycles that would last nearly 10yrs. I would never expect a FLA even in the best conditions to last 10yrs. Also for a weekend place skip the more pannels and get more batteries, they will have 4-5days to recharge.
+1 here. I use AGMs as they are in my house, but no maintenance and lasting well. I use AGMs not because they are the best, but because I wanted low maintenance sealed batteries that will work when it is cold. If I could keep them warm all the time, I would have gone LiFePO4.
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gcrank1
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# Posted: 21 Feb 2021 03:11pm - Edited by: gcrank1
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Just when I think I have a handle on what to do.....
Up front buy-in cost: Just examples and easy to make multiples of for calcs.
2x100ah 'marine' bats, $210ish, net 50=$4.20ish/ah (25% dod)
2x6v 220ah in series for 12v, GC2, $230ish, net 100ah=$2.30/ah (50% dod)
2x100ah AGM (prem), $550ish, net 100ah=$5.50 (50% dod)
1x100ah LFP, $600, net 80ish ah=$7.50/ah (80% dod)
Then perhaps the more meaningful 'cycle costs':
Marine-400? cycles, 2-3yrs life, .50ish/cycle
GC2-1000? cycles, 5-6yrs life?, .23ish/cycle
AGM-1000? cycles, 5-6yrs life?, .55ish/cycle
LFP-3000? cycles, 10+yrs life, .20ish/cycle
Imo the 'marine'/rv batteries are Not in contention, just used as a commonly used example.
The GC2's compare favorably to the LFP in cycle life costs though fall short on lifespan. Ignoring lifespan and taking the chance that LFP may become more reasonably priced (or another even better battery may be developed by the time the GC2's need replacement) I am not using a 10yr all-in costs including bat-bank replacement.
Nor am I forgetting the GC2's require maintenance because I am able and willing to do such.
The last consideration regarding LFP is that the up-front purchase price is money gone that can well be spent on, say, lumber this year.
Unless Im off in my calcs/considerations above the GC2's appear to be a reasonable choice for an essentially '3 season/weekend' cabin situation.
Yep, just like Ive been told previously 
They seem to make sense but they still aint sexy
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