|
| Author |
Message |
Steve Thorn
Member
|
# Posted: 23 Aug 2020 01:18pm
Reply
I have 5 year old lead acid L16 batteries x 8 and I have to replace them.I have been told to go to12- 2 volt lead acid and I should get 12-15 years out of them.I run 2600 watt solar,700 watt Pelton Wheel and have a Back up generator .We currently use 850 kwh a day and live full time off grid.I cannot find anybody with Lithium knowledge to convince me not to use the 2 volt batteries .Any ideas out there will surely help.
I am on the Sunshine Coast in BC,boat access only.
Thanks
|
|
SCSJeff
Member
|
# Posted: 23 Aug 2020 06:52pm
Reply
For what it's worth, I think I'm sold on lifep04 now myself. (I think I even started a thread a while back saying I couldn't justify the cost) 
I just purchased a single 100AH Battleborn for testing and used it this past weekend running my freezer/fridge conversion. The ability (and piece of mind) of being able to run it down lower than LA is nice and the speed of recharge was amazing compared to my LA setup.
That being said, if you have the space and are careful about how you cycle them, you probably are still financially ahead with the 2V batts (assuming you really do get 15 years). The lithium would be great if you wanted to go smaller in space usage. But, you do want to keep them above freezing if possible (at least while charging) which can be a pain.
I've decided to head towards a full lifepo4 setup and move it inside my cabin, instead of the unheated shed where my existing LA batts are.
|
|
Nobadays
Member
|
# Posted: 23 Aug 2020 07:19pm
Reply
I'm a lithium user as well, mine are upcycled Chevy Volt modules, 12kw of storage. We too live pretty much full time off grid and use electric appliances... fridge, freezer, microwave, washer, etc. As Jeff has said above they need to be above freezing to charge but with a good BMS they are pretty much "hook up and forget." I don't know much about the 2v LA but I find it hard to believe any LA battery will last 10-15 years, most FLA/AGM/GELS will average 5- 8 years, maybe 10 if you keep them at a steady temperature and never discharge over 50%. It is highly likely lithium will last begween 10-15 years.
The only thing I would do differently is probably opt for Battleborns or similar with the built in BMS that includes, over charge, under charge and temperature protection.
Our 12kw of storage gets us 3 days without sun.... only you can answer how much storage you need. Looking at the 2v LA I see their AH rating/ storage capacity is really high.
|
|
ICC
Member
|
# Posted: 23 Aug 2020 09:42pm
Reply
Lithium seems to be the future, now. I presntly have GBS prismatic cell LiFePO4. Big cells not little cylindrical things like some others.
What kind of 2 volt batteries or cells? The L16 type which are really a standrad three cell L-16 but wired in parallel instead of series? Or the big Rolls/Surette type? Some of the Rolls are warranted for 10 years. My first big system used them and were 15 years old when I sold the place. They were still working well enough, maybe 2 or 3 more years.
Lead-acid are less money up front but need more maintenance than lithium. L-A are also much more forgiving to errors in operation. But I sure do love my GBS cells.
|
|
paulz
Member
|
# Posted: 23 Aug 2020 10:58pm
Reply
Quoting: Nobadays Our 12kw of storage gets us 3 days without sun.... only you can answer how much storage you need. Looking at the 2v LA I see their AH rating/ storage capacity is really high.
Hey Nobadays, I've been trying to understand your 12kw storage (is that kwh, hours?), vs. the AH rating that batteries have. Can you elaborate?
|
|
Nobadays
Member
|
# Posted: 24 Aug 2020 08:57am
Reply
Solar/electrical math is not my strong suit but I'll try. (I would love any schooling from those who understand it better! )
The 12KW of storage refers 12,000 watts available for use, (though I have seen these modules advertised as 2Kwh... maybe that is right?) My understanding is a kilowatt hours is a measure of energy usage, 1,000 watts for 1 hour is a kilowatt hour. So, the 12KW could sustain a 1,000 watt load for 12 hours... theoretically! Of course like any battery you can't drain to zero... 80% though is doable with lithium. So at 80% I have about 9,600 watts - or 9.6KW of usable storage. If you now divide that by my battery bank voltage 48v, it comes out to 200AH usable.... which doesn't seen like much at all! But since a LA battery can only be discharged 50% - if you want to make them last longer more like 40% you are looking at an equivalent to 400-600 AH of storage.
Now to throw a monkey wrench into this... the 2KW Chevy Volt modules are actually rated at 47AH each, or in reality 2.256KW at 48v. So, in actuality my 12KWs are 13.5KW, or 282AH, with 225.6 usable.
Real life... Or how I get 3 days with no sun (very rare but snow on the panels isn't). I use... or I should say my charge controller puts on average between 70-80AH a day into my battery bank. If we know we won't likely be producing much power for a day or two... storms rolling through, we reduce our usage - no TV, limited internet, no using the oven (glow bar gas oven), etc, our usage drops to 60-70AH or less. At 65AH a day we would use approximately 195AH/9.4KW in 3 days.... and that's how it's done!
|
|
Brettny
Member
|
# Posted: 24 Aug 2020 09:50am
Reply
Theres no doubt lithium is a far better battery than a flooded battery but this comes at a cost. Becids needing to switch your batteries you need to make sure your charge controller and inverter will work with lithium. They can have a wider voltage swing than flooded batteries.
For our place I went with the cheapest new flooded batteries I could find. We only use it 1-2x a month on the weekends so 500 cycles could last us nearly a decade. But when I bought a charge controller and inverter I made sure they would work with lithium. I imagine that in 10yrs lithium will be alot cheaper.
|
|
Steve_S
Member
|
# Posted: 24 Aug 2020 10:26am - Edited by: Steve_S
Reply
I am running 100% offgrid with 2kw of Solar, Midnite Solar Classic-200, Samlex EVO 4024 with 24V battery system.
I switched over from 8 Rolls S-550's (428AH net) to LifePo4 of which I now have 910AH (21.8kWh) gross (100%). 2 Packs of 280AH and 2 packs of 175AH.
FLA Batteries can only discharge to 50% DOD to remai within safe range & to prolong lifecycle.
LFP Batteries can discharge to 100% DOD BUT for longevity & safety, most restrict that to 80%, leaving 10% at the top & bottom/
NOTE, standard Prismatic LFP cells can discharge & charge at 1C rate. 200AH cell can output 200A and take 200A for charging. Some chemistries even higher (at much higher $).
8X 280AH LFP (LiFePo4) which I purchased fom Xuba Elecronics (Alibaba).
8 PCS of 280AH delivered to door DPP: US$1,093.52 which is 136.69 per cells delivered taxes/duty paid.
XUBA 280AH cells.
Alternately, their sister company Luyuan has some other deals as well in Bundles. LUYUAN Tech LFP cells.
PERSPECTIVE:
Battleborn 12V/100AH battery = $1307 CAD MSRP
RELiON 12V/100AH RB100-LT = $1496 CAD MSRP
Each battery pack would require one BMS (Battery Management System) and a fuse of course.
12V - 4S battery pack would require 4 cells and a 4S BMS.
24V - 8S battery pack would require 8 cells and a 8S BMS.
48V - 16S battery pack would require 16 cells and 16S BMS
BMS:
There are many types of BMS' whic have a variety of functions, capabilities, of course that is reflected in the pricing. A very "A-Typical" smart BMS with Bluetooth functionality (monitoring & configuration) will run about 150 USD. These are FET based and typically CAP at 200A output & max of 100A charge input. BMS' that handle above 200A usually use Relays/Contactors to disconnect the battery pack if an error condition arises. These tend to be more expensive but more reliable as well for heavier use. Your Needs and Wants would determine what is better suited to you application.
The BMS will monitor each cell within a pack. It guards the cells against Over/Under voltage, Over/Under Temp conditions and will cutoff the battery if the paramters are exceeded to protect it. Some BMS' have Passive Balacing while others (more $) have Active Balancing.
I myself use Chargery BMS8T-300 bms8t link along with the new DCC (Solid State smart relay system) which are just about to ship out as these are more efficient than standard relay contactors.
More info on the DCC (see my draft doc)
24V Battery Pack Assembly with Prismatic LFP
NB: This shows with Paralleled Cells within a pack. This is not generally recomended with Large Capacity cells The Internal Resistance tends to vary more along with the cell capacity and through cycles. These are NOT mAh cells.
|
|
|
Steve_S
Member
|
# Posted: 24 Aug 2020 10:57am
Reply
Why LiFePo4 (LFP) over other Lithium Ion Chemistries ?
https://www.youtube.com/watch?v=Qzt9RZ0FQyM
SPECIAL SIDE-NOTE: LFP cannot be charged when below 0C / 32F, depending on your region, certain precautions may be required like a light battery warmer or have the battery packs in a heated / conditioned space. LFP with Ytrium can be used in sub-zero temps but they are very expensive.
WARNING:
Lithium Based Batteries in general and LFP more specifically, while very similar to FLA/AGM Voltages, charging them requires only Consant Current / Constant Voltage. They DO NOT take Equalisation! Whatever charging system is used (Solar Charge Controller, Inverter/Charger, AC to DC Charger, it must be settable for use with Lithium or preferably LFP specifically.
Good quick guide to Happy Life with LFP:
https://www.solacity.com/how-to-keep-lifepo4-lithium-ion-batteries-happy/
|
|
Nobadays
Member
|
# Posted: 24 Aug 2020 02:18pm
Reply
Good information Steve! I, as you know spend some time on the DIYsolar forum as well, but find it often difficult to search and find information, especially clear information about building your own LFP packs.... kind of info overload! This explanation is simple and easy to follow.... I may do this down the road, that said I probably have another 10-15 years left on my Chevy Volt modules so who knows what technology will look like then.
Thanks!
|
|
Steve_S
Member
|
# Posted: 24 Aug 2020 05:44pm - Edited by: Steve_S
Reply
The easiest format to work with in my opinion, is the square / rectangular cells because of the busbars , wiring and "packaging" into a case or something. The info is there on Diysolarform and being so busy, it can get hard to find specifics or you get overwhelmed with info. Damned Catch-22 I think. hehehe
Here's a pic of of the inside from one of my 280AH packs. Shows the simplicity of it, compared to other types.
24V/280AH assembled into the box
|  | | |
|
|
ICC
Member
|
# Posted: 24 Aug 2020 07:13pm
Reply
It may be worthwhile to mention that prismatic cells must be encased in a tight fitting box or plates that help keep the cell walls from bulging.
|
|
paulz
Member
|
# Posted: 24 Aug 2020 07:51pm
Reply
Quoting: Steve_S I am running 100% offgrid with 2kw of Solar, Midnite Solar Classic-200, Samlex EVO 4024 with 24V battery system.
Hi Steve. I have been considering a Midnite Classic but the material I read said they are not designed for LFP. Can they be reconfigured?
|
|
Steve_S
Member
|
# Posted: 24 Aug 2020 09:16pm
Reply
The Midnites are very programable and it's not a problem, I am disappointed however that Midnite Inc does not have specifics related to Lithium batteries as such. At the time I started, Victron was just coming into Canada and I chose this.
If I was doing my system today, I'd go all Victron TBH. It all integrates well, the support docs, info & material is "Excellent" and they are a Tier-1 product, so you do get what you pay for. They do have the ability to interact with various BMS' which can have good benefits but not all obviously. Victron SCC & Inverter/Charger combo is a no-fail setup.
Not to say I am unhappy wih the Midnite & Samlex combo, it works really well for my purpose and has actually allowed me to use some "creative juices"... hehehe
|
|
justinbowser
Member
|
# Posted: 25 Aug 2020 11:21pm
Reply
Quoting: Steve Thorn I run 2600 watt solar,700 watt Pelton Wheel and have a Back up generator .We currently use 850 kwh a day
I must be missing something here. 850 kwh is a mess of juice...
We use an 800 AH 24v LiFePO4 bank at our cabin...
|
|
Nobadays
Member
|
# Posted: 26 Aug 2020 09:04am
Reply
Agreed.... Not quite sure how the OP arrives at that. The 2,600 watts of PV could potentially produce about 8kw/day and the Pelton Wheel a whopping 16.8kw so a total of ~25kw/day. If they are using 850kwh/day there is a major deficit here.
Hopefully this OP returns with an update
|
|
|
