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Small Cabin Forum / Off-Grid Living / Taking the LiFePO4 Plunge
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justinbowser
Member
# Posted: 3 Mar 2020 22:30
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I have decided to take the plunge and replace my AGM battery bank with LiFe. I have just received 3 24V 200 AH battery assemblies and will parallel them to make a 600 AH bank.

Here is the battery:

https://pacificsunsystems.com/catalog/product/24v-200ah-lifepo4

I am going to take them up to the cabin and install them next week and I will let everybody know how it goes.

SE OK has a lot of rain certain times of the year and there are numerous periods of consecutive cloudy days so I decided I needed a more robust battery bank then the 300 AH AGM bank.

I will need to build an insulated box for them with a small DC heating element to keep them above freezing in the wintertime when we are not there. Hopefully I can find a heater that will keep the batteries happy without taking too much juice.

ICC
Member
# Posted: 3 Mar 2020 23:01 - Edited by: ICC
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Quoting: justinbowser
I will need to build an insulated box for them with a small DC heating element to keep them above freezing in the wintertime when we are not there. Hopefully I can find a heater that will keep the batteries happy without taking too much juice.


If you are not there will they be powering something or sitting idle? If sitting idle they do not need to be kept warm. And they can sit for months on end at a partial state of charge and are perfectly okay

mj1angier
Member
# Posted: 3 Mar 2020 23:15
Reply 


I think they have to be above freezing when charging. So if on solar system, see if it has a temp senor that can cut of charging around 35?

Nobadays
Member
# Posted: 4 Mar 2020 08:29
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We got some seed bed ... mat type... heaters for our modules. Yet to put them in the battery box. Those or RV tank heaters are what are commonly used. Use a separate temperature controller to turn the heaters on and off.

ICC, mj1 are both right.... we leave our lithium modules at 80% charge then turn off the system when we leave. When we return we turn the inverter back on... but leave the breakers off from the SCC/panels until the modules are well above freezing. We have two separate digital temp guages with their probes taped and insulated onto the modules (two different ones.) We look for 40+ before starting to charge. The 80% left in the modules will get us pretty close to two days if we conserve power, plenty of time to warm the cabin/lithium modules up. As mj1 said, it is only charging when cold that damages the modules. We have yet to spend the time/money to install a low temp cutoff system.... our SCC does not have that ability. If your equipment is newer... or you are getting a new SCC look for that feature. Victron has it I believe and others are now building it into their SCCs.

BTW our modules sit in a battery box on 1" of foam insulation and the box sits on another 2" of foam.

mjrtom7
Member
# Posted: 4 Mar 2020 08:55
Reply 


I've been wrestling with how to solve the temperature issue as well. I'm planning to build in northern Michigan. I'm thinking I may build a bunker of some sore (hole in the ground, with insulated top) that goes below the frost line (6-8 ft deep) so that the LiFePO4 batteries wont freeze and can charge freely.
Has anyone ever done something like this? I'm not sure it will work...

FishHog
Member
# Posted: 4 Mar 2020 09:12
Reply 


both ideas will work as long as they don't freeze. But it is important to note what has been said above. Unless your charging them, they are fine to freeze. So unless they are powering something while your away, just shut things off and let them freeze.

Warm them up when you arrive if you will need to charge them.

Or find a charge controller with a temp sensor and let it charge when its warm enough.

Steve_S
Member
# Posted: 4 Mar 2020 09:14
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You may find this particular message thread / review of use. He opens it up and goes deeper into them.

https://diysolarforum.com/threads/review-pacific-sun-systems-specializedpower-24v-200 ah-lifepo4.2846/

You can safely discharge LFP up to -10C/14F but charging below 0C/32F is harmful. The general consensus is charge above 2C/35F. Ytrium LFPY is more forgiving for temps but also cost significantly more.

By the end of this month, I will be running with 2x175AH & 2x280AH for a total of 910AH / 21.8Kwh of LFP as I am retiring my FLA bank to Greenhouse duty.

I'm building my own packs, using Grade-A EVE-280AH cells ($84ea) from Xuba Electronics and Chargery BMS8T-300 BMS/Balancers (about $120 USD) PLUS S&H.

REF LINKS:
https://www.alibaba.com/product-detail/Hot-Rechargeable-3-2V-280Ah-LiFePO4_6240146918 5.html?spm=a2700.icbuShop.0.0.764520d22qNJc8&bypass=true

Chargery BMS/Balancer
Buying direct with relays & delay board

1x BMS8T $90
2x 12V/200A Relay, $36 ea
1x Relay Delay Board $4.50
1x Express Shipping $30
1X PayPal fee $10
Total: $206.50 USD


http://chargery.com/BMS8T.asp


24V/280AH pack with EVE-280 cells.
8 cells US $678.32
Ship to United States by Express Seller's US $415.20
-- Lead Time 15 days
-- Shipping time 18-25 days
Total US $1,093.52


TOTAL COST for 24v/280AH
1093.52 + 206.50 = $1,300.02‬ USD

Nobadays
Member
# Posted: 4 Mar 2020 09:56
Reply 


Quoting: Steve_S
By the end of this month, I will be running with 2x175AH & 2x280AH for a total of 910AH / 21.8Kwh of LFP as I am retiring my FLA bank to Greenhouse duty.


Holy cow Batman! (er... Steve!) 910ah of LiFePo4.... that's a lot of storage! But reasonable for sure if you DIY your modules. We use 4/48vdc/2kw Chevy Volt modules at roughly 42ah each... total of 168ah (granted this winter we figured out we need a little more to go a full 3 days without sun). We are able to power a small freezer, 10cuft fridge, microwave, satellite internet, TV and of course lights with no issues until we get into that 3rd day.... We plan to add 2 more 2kw modules this summer which will bring us to 12kw/252ah.

With the BMS (Creeky's build, no low temp/over charge protection) we have about $1,800 in our storage.... in hind sight we might have been better off with a couple of Battle Born units @ 100ah each and built in BMS... for around $2,000.

We are gearing up for a small FLA bank/SCC/Inverter to run the satellite internet/web cam for winter. Tried a cheap fix this winter but failed horribly with my solar math! Plus tried to use a couple of used AGMs -"barely used"... right! They turned out to be toast. But... I did score 6 more 250 watt panels at Santan Solar on their Valentine's day special @ $37.50 each!

Steve_S
Member
# Posted: 4 Mar 2020 12:30
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Well, I have tweaked adjusted and worked through many days of no sun and having to run GenSet to charge the FLA's which are in distress and had to make the choice. I'm using on average 4kwh per day and 3 days autonomy just isn't cutting it. With the FLA I can squeeze 428AH maybe a touch more but that's it. With the LFP, getting 80% from a pack is easy enough.

I managed to get Jason Wang at Chargery to update & mod the firmware, they now have Low Temp Charge Cutoff, Low Temp Discharge Cutoff and within a month or so, should have the Bluetooth module completed.

The Santan Solar deals are incredible unfortunately not good if your shipping to Canada... I did find these guys in Ontario and it's NOT BAD but I am sure there could be others but haven't found any.
http://solarshoppingmall.com/24V-Solar-Panel_c_25.html I'm in need of MORE PANELS ! Peaze Sir, moar !! Looking for a LOT of 20 panels, 60 Cell 250-300W and also another Midnite Classic for the Powerhouse and another SCC (Solar Charge Controller) for the Greenhouse.

LFP is so nice to work with and without many hassles. Now that prices are reaching respectable and making FLA almost pointless, I don't see FLA/AGM having much lifespan left. Best part with LFP, very easy to DIY packs and get some serious storage happening.

BattleBorns are good stuff and Will Prowse has eve n torn them up and thrashed them hard and still all good. But at $1K USD for 12V/100AH they are steep, BUT 10 year warranty, great service & support & THEY Honour Warranties too, it's a good solution for those who have the $$$ to spare. It's ironic but I can build the 12V/100AH pack with BMS for < $500 USD as I hooked up with manufacturers & wholesalers in China and holy cow, there are deals to be had for Grade-A New & Tested Cells.

This isn't the forum for such discussion and this Thread has been hijacked enough. The "other forum" shown previously is where we cover all this stuff in serious detail.

IF Anyone is curious about other cell sizes (in AH) have a look at the link below. These are CATL Cells sold by Deligreen at a VERY GOOD PRICE but pay close attention to the description, and note that in "bundles" of 4 or 10 the per cell price sometimes cheaper. They also have "kits" with the bus bars & bolt kits included. They are NOT my primary supplier but many are using them and are happy.
REF:
https://deligreen.en.alibaba.com/productgrouplist-812616358-1/CALT_Battery.html?spm=a 2700.icbuShop.41413.dlhlist.764589b6Soam17&filter=null&isGallery=N

justinbowser
Member
# Posted: 4 Mar 2020 16:53
Reply 


Steve - Thanks for the link to the review.

The batteries I received look very well constructed, robust, and heavy! Each module weighs in at about 115 lb and were well packed in custom fitted wooden crates lined with foam padding, came with cables to parallel them with, and all hardware.

One thing about the battery price is it includes shipping. They came from China by slow-boat to CA and from there were here in a couple days by Forward Air.

The reason I am considering a heater is the battery specifications give a storage low temperature limit of -5 C so I did not want to do anything to damage the batteries.

Nobad - Thanks for the tip about the seed bed heaters, I'll check 'em out.

Nobadays
Member
# Posted: 4 Mar 2020 20:01
Reply 


Justin.... the RV tank heaters are 12vdc I believe...

justinbowser
Member
# Posted: 5 Mar 2020 10:36
Reply 


Seems all of the tank heaters I've looked at have a built in thermostat. Now, the "elbow heaters" do not appear to have an internal thermostat. The 3" x 13" is rated at 7.5 watts and I could put one under each battery inside the insulated box. Tie them to a programmable thermostat and see what happens.

Steve_S
Member
# Posted: 5 Mar 2020 10:58
Reply 


I feel I should mention this wee detail. LFP cells like the same temperatures that humans do and are ecstatic between 10C & 25C temps. They also do NOT offgas or have any of the risks that appear with Lead / AGM or even Lithium Ion MNC, CA and similar chemistries. IE they do not catch fire or explode. You can quite safely have them in your home in the same temperature you live in. LFP is used for hospital equipment, including in restricted High Oxygen environments because it is safe.


Here is a GREAT VIDEO on the diff chemistries being "abused" and what they do. GOOD WATCH !
https://www.youtube.com/watch?v=Qzt9RZ0FQyM

Nobadays
Member
# Posted: 5 Mar 2020 17:47
Reply 


Justin... FWIW... I think it is kind of common practice to put the heating pads under something like a sheet of light aluminum rather than directly under the modules.

ICC
Member
# Posted: 5 Mar 2020 18:42
Reply 


Quoting: justinbowser
. Now, the "elbow heaters" do not appear to have an internal thermostat.


Depending on how comfortable you are with electricity and electronic gizmos, the thermostat controllers linked to here work well. I have several in use. They are available in DC and AC versions. They use a remote temperature probe. Usually, they are limited to switching 10 amps maximum. Some only read in C, others F and C. An ebay search will find many sellers.

justinbowser
Member
# Posted: 5 Mar 2020 19:09
Reply 


Nobad - Good tip, I have a big sheet of 1/8" aluminum.

cspot
Member
# Posted: 5 Mar 2020 21:08
Reply 


Battleborn makes this.

https://battlebornbatteries.com/shop/heat-pad-for-bbgc2/

justinbowser
Member
# Posted: 5 Mar 2020 21:21
Reply 


Ouch! A bit pricey, I think I'll try the elbow heaters first.

ICC - Thanks, something like that is what I'm thinking of and if I ever need higher current I can put in a relay to take the load.

creeky
Member
# Posted: 10 Mar 2020 10:51
Reply 


I use battery heater pads. Insulated box. Works great.

If you put them in the ground below the freezing point make sure your above the spring run off water level. At my place a hole in the ground quickly fills with water.

Steve asked me to build a pack for him. Then took the info I gave him and used it to build a different pack. No worries. He then gives away my BMS info as if its his. No worries. I'm here to help. But a nod to the hours of help I've given him over the years wouldn't be amiss.

Brettny
Member
# Posted: 10 Mar 2020 12:27
Reply 


Quoting: Nobadays
the RV tank heaters are 12vdc I believe

Not including the thermostat heaters are just dummy loads and don't care what voltage or ac/dc. I would not use a 12v heater on a 120v circuit though. 120v to 12 yes.

I made a egg incubator years ago and found cheap geid resistors (I will look it up) and a STC-1000 controller for a thermostat. They make the stc-1000 in 120, 12 and many other voltages.

Steve_S
Member
# Posted: 10 Mar 2020 13:55 - Edited by: Steve_S
Reply 


CORRECTION:
Info creeky provided WAS minimal and related to USED VOLT packs - NOT LFP !
BMS info HIS ? REALLY ?? Chargery is a big enough company with lots of exposure and are listed here as well as many others. BTW I am rewritting their docs for them to clarify the English.
http://liionbms.com/php/bms_options.php

HELP: ? In 2015 I offered to put creeky up in a Bed & Breakfast, pay his expenses plus for a couple of days help building my 1st system, I got back a "shit on me" email which I still have in the archives somewhere. THAT WAS BEFORE BOBOLINK ! or his GF happened. IN fact he told me I was the first person to buy him a beer on his donation tag on his old original Creektreat CA website.

He did help a bit but in the most cryptic and unhelpful manner, at which time I figured I best learn as much DIY it and SHARE all the knowledge FREELY without requiring ANY profit incentive, so now I share ALL knowledge and accept / WANT Nothing in return.

One advantage of having a partial eideic memory and being a former High Tech Engineer, it all sticks.

So yes THANKS for leading me to be independent and pushing me to educate myself in depth on this subject matter to the point where I can freely share the knowledge gained and help others get free of the grid or whatnot.

Have a Great One !

PS: It's also one reason (byproduct) as to why I gave up updating my build thread and others... share with others so they share with you. Ahh but there is NO PROFIT in that is there. too bad for the ferenghi !

If you want to see the useless email exchange & the pricing he offered I can post it... He also does not mention how pricey his option was … with little budget t spare I had to maximize every dollar & penny. I'm not a rich fool.

qbodsyt
Member
# Posted: 10 Mar 2020 15:26
Reply 


Steve_S
Without commenting on the other member or their claims, I just want to thank you for all the well written and informative posts you make on this site.

I really really wish you would update your build thread as I find your build and the mentality behind it very inspiring. Your DIY spirit and the logic you employ to execute it really has helped me to learn a lot from slab to solar. If ever I was able to make my dreams a reality, I would probably be offering you consultation fees, particularly for your work with the Raspberry Pi.

I really hope you will stay active here. Best wishes

ICC
Member
# Posted: 10 Mar 2020 16:10 - Edited by: ICC
Reply 


Quoting: Brettny
I would not use a 12v heater on a 120v circuit though. 120v to 12 yes.


As long as there are no motors or electronic controls that is usually safe. It should be noted though that using a heater designed for 120 volts on lesser voltages will result in reduced output. For example, a 120V 1000W heater element will only produce about 40 watts worth of heat on 24 volts, even less on 12 volts. Conversely, if the heater element was designed for 12 or 24 volt use and it was run on 120 volts the element will almost certainly burn out quickly after producing a great amount of heat for a short time. That would also be a great risk of starting a fire if the fuse or breaker was sized too large.

creeky
Member
# Posted: 12 Mar 2020 10:12 - Edited by: creeky
Reply 


Sorry Steve. Say what you will. You asked me for information about my equipment and then you went a different direction. No worries.

I spent dozens of hours on your first build helping you, help you asked for. Even begged with all these messages about crappy used equipment. When it came time to pick up equipment you were too busy to stop by even tho you were a few minutes away. Still waiting for that beer.

And the rental thing was so I could come help you build your place for free. A great offer. Not sure why you're so upset about giving credit where due.

However. For everyone. Building a 910 amp hour battery at 24v is not the best idea. Go 48v. 1/2 the amps into all your wiring and your control equipment.

LifePO4 is okay. I've been promoting it on this site since 2015 and maybe earlier? The Volt cells are superior however.

I fired up my lithium pack on July 01, 2016. And haven't had to even look at it for over two years now.

And, I know the guys who worked on the BlueBIRD BMS, they worked very hard to improve the level of resolution on voltage. It was difficult to say the least. That's why I sell them. And recommend them.

Build on!

justinbowser
Member
# Posted: 18 Mar 2020 23:44
Reply 


I installed the Specialized batteries last week and I'm happy as a clam! Always wondered about that saying, but I digress. I reconfigured my Classic 200, un-cabled the AGM batteries, hooked the LiFePO4 batteriesvto the bus bars, and turned the breaker back on. Wow! I have never seen so much current coming out of my CC. Just as soon as the sun came out from behind a cloud I was pumping about 77 A into them! The 10 Ga wire between CC and batteries got very warm so I will be changing that out to 8 Ga in the next day or so.

There has been very little sun since I hooked the up and over the past week I have only used the genny twice to help bulk after 3 days with no sun.

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