Opinions and perspectives on current LiFePO4 battery brand choices for off-grid

Fenachrone

My completely non-expert impression is that SimpliPhi is highly regarded, maybe considered the best of the bunch.   I've also seen a lot of attention around Kilovault.  What strikes me as curious, though, is the fact that Kilovault and alt-E, an RE distributor, have the same physical address.  The late solar queen at alt-E, Amy (RIP) mentions in a video that the two companies have some relationship, but it's not clear what that is.  And that's not to say it's a problem, but like I said, just curious. 

How about Battle Born?  I haven't noticed a lot of people using them for off-grid, but they are selling direct, so maybe that's the reason -- you don't see them on the usual retail sites. 

There are others: Dakota Lithium, Big Battery, Discover, Ionic,RELiON, Canbat, Rolls...  I also notice someone put up a video showing that he bought China-made batteries on Alibaba and saved big $$$.   Seems like he has quite the load of batteries for $3800.  https://www.youtube.com/watch?v=fST2IPyNUy8

What I'm primarily interested is the experience people have had with their particular lithium batteries in various off-grid situations, as measured by reliability and performance. 

Thanks for all responses.

Wheelman55

Make sure that you read the fine print on both batteries and electronics regarding minimum and maximum number of batteries. 

I was an early adopter in 2018 with one Discover 48 v battery on a Schneider closed loop system. 

The original battery had internal wiring issues. Discover replaced the battery last spring. 

I added two more Disco batteries for a total of three about a year ago. During that time Schneider added a note that my gear needed a minimum of two of the Disco batteries and a maximum of three on my system. There was no mention of this in the 2018 user guides. 

The batteries and system have been working well. I’ll report back in on this in five or ten more years:)

See my signature below for my system specs. 

FYI. You can only see signatures when on the full site, not while on the mobile site. 

JRHill

Fenahrone, would you please list your system components?

I'm at the 2yr mark with 3 of the SimpliPhi 3.8-48. It was a $ hit but then batteries have always been that. With my original 12yo VFX3648 I didn't have a good experience with using the FNDC battery monitor's relay as a low voltage shut down per the Outback's application notes and had an inverter malfunction. I replaced the VFX with the FXR - the FXR has configuration options suitable for the higher low voltage cut out needed for the PHIs (in addition to some other improvements). I was so happy with the outcome I bought a 4th PHI 3 months later and reconfigured the PHI bank into a 2x2. I have more battery than needed and they have an easy life. And if one fails, Lord forbid. I can still get by with 3 in the low light season. It wouldn't be so easy with a bank of 3 and falling back to 2.

So to your question, here it is: IMHO the SimpliPHI stuff was well done and their only competition is cheaper batteries. I can't give you details on any variances between the individual blocks as they are tied together. The Battery Monitoring System (BMS)? I haven't needed a hi/low voltage cut out nor anything else out of the BMS programming that I know of to date.

My priority was to get rid of lead once and for all and all the maintenance, watering, SGs, danger, etc. Now I don't have much to do but look at charts and graphs. And to start/stop/fuel the generator. But if something happened to me and the DW had to do the operation its more than convenient and I can die well. Without more morbidity, that was always an elusive goal. And it was ALWAYS centered on batteries.

That's about all I can say from my perspective. Experiment to your heart's content but what you have, you have. You can't intermix PHIs with other lithium's anymore that you can with lead blocks. So I chose to get the best I could at the time. It this point I believe they will outlive both me and the DW.

Fenachrone

JRHill, thanks for commenting on your experience with the SimpliPhi's.   My components are Outback MX60, Outback VFX3524, and Mate, Midnite Solar E-Panel, Trimetric, and six 235w panels.  I will be adding another approx 1000w this year.  The Outback components were installed in 2007, panels upgraded in 2015 .  They are in a summer residence with a fixed, horizontal array -- plenty of long summer days in a northern location.   We have pretty low electrical demands in this small house.

Your comments about the compatibility with older Outback components are echoed by some others, though SimpliPhi's product information states their batteries are, and I quote " Compatible with all industry-standard inverter charge controllers".  Swapping out for a new CC will be a challenge in my remote area with a scarcity of knowledgeable personnel, but if it has to be done, so be it.  I think I would contact SimpliPhi to get their thoughts on this.

My priority is to get beyond lead batteries, as well. 

Horsefly

I had mostly decided that the SimpliPhi et al batteries were just too expensive, and that I'd have to stick with lead-acid. Then I learned that I could by my own cells and BMS, and add my own thermostat-controlled heat to keep them safe over the winter, all for a fraction of the price.  It isn't for everyone, but I'm a retired electrical engineer and like the tinkering.

I ended up with a 24V 230Ah battery, which - given you can use much more of the total Ah of the battery - is significantly more than I had in lead-acid.  The battery has been awesome so far.

I know others here have successfully gone a similar route as me, but I can really understand someone wanting to buy the off-the-shelf assembled battery and pay the extra price.  Fact is, some of the rack-mount 48V packs that are flooding the market are hard to beat.

Marc Kurth

No direct hands-on experience, but I have several PV Contractor customers who regularly install Fortress. They are happy because their customers are happy. I have not seen them installed on the larger off grid residential systems yet, but I see them being applied in the 15-35 kWh battery bank range to replace the most common sized 40-55 kWh AGM banks. The larger 80-100+ kWh AGM battery banks that I sold 9-10 years ago are aging out now. It will be interesting to see what comes out of the decision process because the AGM banks were designed for 10-15% average daily DOD.

Our host sells Fortress - give them a look!

Dave Angelini

Your electronics are also important if you go the LFP route. Schneider is closed loop charging and discharge with about 10 different battery manufacturers including Fortress. The BMS controls the electronics in closed loop. One of the other large Electronics (inverters and devices) has nothing but open loop charging. You should know the difference and know what you are giving up with open loop.

It may not be a big deal in a cabin system but in a home with normal home loads and big storage requirements, Game changer!

Especially if you rack up alot of Genset time.

JRHill

Dave Angelini said:

Your electronics are also important if you go the LFP route. Schneider is closed loop charging and discharge with about 10 different battery manufacturers including Fortress. The BMS controls the electronics in closed loop. One of the other large Electronics (inverters and devices) has nothing but open loop charging. You should know the difference and know what you are giving up with open loop.

It may not be a big deal in a cabin system but in a home with normal home loads and big storage requirements, Game changer!

Especially if you rack up alot of Genset time.

Dave, I always appreciate your wisdom and input. I am still pondering this thread. Firstly, "cabin" often suggests occasional and maybe even seasonal use. With my system which is a full time cabin, if we were to not be here for an extended period of time and with a bank of gawd awful expensive PHIs and I wanted to protect my investment, I would charge, as in ABSOLUTELY control, the bulk voltage down to where it maxed out at 60 to 70% range. But we don't know where Fenachrone's system/cabin/usage is either. So the charging should not happen if the cabin environment gets below the manufacture's specs in cold weather. It just plain shouldn't charge then. Lead batteries don't typically freeze for a long time if stored fully charged at the beginning but the self discharge sucks, not to mention they need to be worked to stay healthy and storage is not a friend. But LifePo4 stuff is *maybe* not your best choice either. There are a lot of things we don't know. They can be expensive lessons and not necessarily to the deficiency of the battery, just the conditions.

In a seasonal situation, unmaintained, I'd haul any of the batteries out and store them in a controlled environment. Any other input? I am just curious.... Hopefully I don't have to deal with this, ever.

JRHill

The ultimate would be to wirelessly connect to the system and if needed, warm the batteries, if they had enough poop to do that. Then power up the heaters under the panels so the snow slides off and started recharging the batteries. If you can do that you can turn the fridge/freezer on for the weekend of food and ice. Oh, and to turn on the heater (propane, of course) so all is warm and cozy when you get there.

I'm teasing, of course. But in these days of automated homes, why not? I'll leave it at that. Sorry, I have to restack firewood closer to the house.... 

JRHill

Good dog.

Graham Parkinson

Nice doggie if he can fix Gators for hauling firewood!  I'm trying to source bits for an electric wheelbarrow to haul firewood out of the forest and over the hills here on the island, but the local e-bike wizards (Grin Technologies) is out of stock on their Li-Ion battery packs, battery controllers and other bits for the e-barrow kits (available "sometime in 2023").

Watching with interest Discover batteries roll out of their new rack mount Element batteries which have built in heaters available - just the thing for intermittently occupied, wood heated cabins on small off grid islands in PNW.

We are in the midst of 45 knot, gusting 58 knot freezing arctic outflows, burning up our best stock of dead standing, bone dry massive maple blocks that fill the stove and last all night.  Hard to keep the pilot light on the backup propane wall heater going reliably in these winds.

The Element battery has full closed loop, high input/output capacity BMS and full wireless support via their Lynk II interface:

            https://discoverbattery.com/products/lithium-batteries/element

Available "Early 2023"

Dave Angelini

Just remember the loop has to have the electronics you choose in the loop. This will get you away from using a battery monitor and your electronics will get Soc and other data from the BMS.

Below you can see these "friends" of mine staying warm running loads up in Canada. They have all this data and more on a cell phone also.

Fenachrone

I appreciate the additional responses.  I've been away a bit and could not comment.  Our cabin is on Canada's Prince Edward Island.  Lows in winter seldom get below 10 degrees F but are typically higher than that.  The house is unoccupied from about November through May.  There is no electricity (inverter off), but typically, with my LA and AGM batteries, I maintain charging with my charge controller on.  It would be no problem for me to remove my LifePo4 ( should I get them) batteries and put them in a warmer place for storage, if that became necessary.  Of course, it would be convenient for my 70 y.o. body to leave them in place -- and they're in a crawl space, to boot.

Horsefly

It may be hard to know without some logging equipment, but it would be useful to know how cold it gets in the crawl space. It's almost certainly going to stay warmer than the outside temperature in the winter, and may even stay above freezing. If that was the case, you could use LFP and not worry about it.

A couple of other comments (sorry I'm also late getting back here):

1. Some of the off-the-shelf LFP batteries have low temp protection. If the temperature gets below freezing, they cut off charging. If it is only going to get below freezing for a day or two at a time, this solution would work.
2. There are a few of the off-the-shelf LFP batteries that also have built in heaters. If the temperature gets near freezing, they will use a small amount of current to warm the cells back up so they can take a charge. The reviews on these seem a little mixed.
3. There's lots of debate about the advantages of closed-loop control between the LFP BMS and the other equipment.  I'm certainly no expert, but...  Most of us don't have it, and I don't think I'd ever spend extra money for it. I'll admit that it means you need to be careful setting up your solar charger and inverter/charger correctly to keep the currents and voltages in-check, but charging and using LFP isn't actually all that different from lead-acid. 

JRHill

Yup to the above. Esp 3. I have SimpliPhi and Outback, If's not closed loop but it looks great. 

But you still have to know what your system is doing and know the programming or some technician is going to make a lot of money.

Dave Angelini

Yes you do have to know what you are doing !  I see plenty of battery power systems and my main goal is to avoid problems for my clients. A closed loop system is going to protect the batteries from most of the bad things that people do. The other end is the fast charge by letting the BMS know all of the possible parameters and how many batteries etc.  The monitoring lets me do a sanity check and the manufacturer can also for warranty in a closed loop.

 25% faster charging time is huge in a large LFP home system. You do have to balance the 3 X cost for LFP over quality flooded bats. 

I have not seen an LFP that protects itself by stopping charge at low temp. The only way I have seen this work is by opening up the battery contactor and shutting down the inverter, which would stop the charging also. More contactors would make the system complicated and introduce more failure points. 

No need for more failure offgrid right?  See plenty of it on the internet these days

Horsefly

Dave - I can't speak for the off-the-shelf LFP batteries, and maybe none of the closed-loop ones shut off the charging current at low temps.  I know most of the BMS's that are available now for custom built LFP batteries do shut off the charging below a temperature you can configure. Except for the largest ones (>200A), they use two big banks of MOSFETs to independently turn off the charging vs the discharging. Better than a contactor, in that the BMS can stop charging at low temps but still provide power to keep the SCC and inverter up.

Dave Angelini

Appreciate that but I really only deal in systems that a non hobbyist would want or could understand. The pix in the first thread here says it all ! Open walls and non protected wiring would or should scare alot of people.

Just the warranty part of what you describe would be a nightmare for someone living in a really remote place they call home. 

Offgrid needs to be super reliable for the owner, and also be easily replaceable for their wife or better half 👍

Also, the standard for the Outback Radian and the Schneider XW is 250 amp main breaker and larger for multiple inverter systems with charge amps over 140adc.

That is the reason so many of the open loop Simply phi batteries were destroyed by overcharge. To their credit Simplyphi came out with a battery that now has a network to protect itself. The ding on Outback, is they still do not have a closed loop system. Schneider fist did this with the LG 48V battery I field tested for Offgrid in 2017. 

Graham Parkinson

Regarding the original posters question about comparing performance of LiFePO4 batteries for off-grid use - Make sure you understand the idle power draws of the specific battery system you are considering. 

To better understand potential impacts on system viability during periods of low PV input from parasitic / system idle losses in "smart" batteries and their BMS's, control systems, networking and monitoring functions, take a look at this exhaustive but revealing 21 page thread in the DIY Solar Forum:

https://diysolarforum.com/threads/battery-banks-parasitic-loads-and-low-sun-hours.56065/

The above thread started with an owner noticing unexplained continuous draws on a Fortress system on the order of 12 to 30 Watts from each battery pack, but expanded to include reporting on experiences with background losses from batteries from other manufacturers as well (EG4, Discover, Enphase etc.). 

One of the conclusions was that before purchasing a battery system, that consumers need to press battery manufacturers for transparent specification of standby losses (not just of potentially misleading instantaneous "system efficiencies").

For those of us in places like the cloudy PNW it's not just the idle power draw of inverters, charge controllers and the like, but surprisingly it's also the power draw of the battery's BMS and their internal draws like contactor relays etc. as well that can drain a battery system in just a few days of no sun.  

Dave Angelini

In places that are challenged for solar, the system design needs to accept a 30 watt constant inverter load and about the same for the BMS and maybe more for multiple BMS that are networked.

With the no cold temp charge issue for LFP,  3 X the cost issue,  over the ocean supply issues,
lead acid batteries can be the best choice for some Offgrid applications.

Graham Parkinson

Certainly there are arguments for still using lead acid in some cases, but they have so many disadvantages for those of us who need efficient storage to get us through week long periods of no PV input.

The recent flood of a huge variety of LiFeP04 batteries shows how many designs have quickly come to market while we are in a development phase of this technology and it's controls.

The potential market for LiFePO4 batteries with more efficient and reliable BMS designs will eventually drive improvements in parasitic loads.   Design improvements like active cell balancing (vs power wasting bleed resistors) and use of gallium nitride power transistors instead of power hungry but reliable relay contactors will replace the cheap and effective but often problematic FET based BMS systems currently used on lower end DIY type battery banks.

There is a really good article on progress with GaN and SiC power transistors here in IEEE Spectrum:

https://spectrum.ieee.org/silicon-carbide

These materials have better efficiency than silicon based FET power transistors and can have better fail safe characteristics as well.

It appears that inverter efficiencies could also really make a step change if based on better power switching technologies as well.

Dave Angelini

When they sell them in the store here I take a look. IEEE is for dreamers in the Offgrid world, I use to be in with IEEE.

 A large well designed system for a home would not be concerned with these small loads. They either have the sun or they run a genset. It cost a fair piece of change to live Offgrid comfortably. It always has and probably always will.

JRHill

Dave Angelini said:

When they sell them in the store here I take a look. IEEE is for dreamers in the Offgrid world, I use to be in with IEEE.

 A large well designed system for a home would not be concerned with these small loads. They either have the sun or they run a genset. It cost a fair piece of change to live Offgrid comfortably. It always has and probably always will.

What an absolute true mouthful. We would NOT have solar except for the $250,000 quote to get power to our neighbors. We are further. We have power and are ahead of the game ONLY because of the comparison to get grid power. That's how I put $11k of Phi replacement batteries and didn't flinch. We are way ahead of any alternative. And we live quite comfortably, thank you. We do whatever we want absent hair blow dryers, etc.

Yup, it costs a chunk of change. But what a cool thing. We don't have power outages. We are our own giant, recharging UPS.

 I did shut the system down two years ago when I put the Phi batteries in service.... The lights haven't blinked since (or beforehand).

Marc Kurth

Most of my PV design/build contractor customers are going with closed-loop LFP battery banks now in lieu of AGM for new residential systems. The pattern for replacing the AGM batteries that I sold them 10+ years ago: Customers tend to stay with AGM if the battery bank is very large but most often switch when the system is smaller.

Dave Angelini

I forgot the third way to charge besides alot more solar and or a genset.

Not trying to be anti social but you have to move to the south west or places that are similar.  

JRHill

Oh, location matters? Or the distance to town?

Graham Parkinson

Thanks for the sentiment but some of us are quite fond of our often overcast skies (they somehow feel "cozy" ).   

Wind power here (the third way to charge) suffers from the really turbulent flow seen on the lee side of the island.

As a result, our area has a growing proliferation of unattended auto-start propane gensets and all the problems that they entail. 

The real kicker though is trying to design an off grid system to store energy through an low or no PV input period that lasts longer than the time for the BMS to drain down the batteries.  No amount of storage or PV will solve this problem, only a more efficient storage system works or a system designed to go into a smart low drain standby, maybe controlled by a Raspberry Pi or the like.

Although this fourth way to charge (wave power) may still be at the DIY dreamer stage, my ex architect/developer boss from student era solar house building days has moved from building solar housing into wave power, in a big way.  He's a few islands over and has had a whole series of private/government funded wave energy research projects moored in various places around here.

Dave Angelini

You will just have to run a genset or keep doing the armchair offgrid here on the forum. 

 Location always matters,  but if you love the place,  that is all that counts,  to me at least.

You might be surprised at how well 8KW + of solar will do. Especially with LFP.  Done it many times for my clients far north of you guys!

JRHill

We are north of the Columbia and about 40mi east of the peak of the Cascades so are officially in the rain shadow. But come the end of October through most of January it is generator season. Looking at the Mate3 system controller at mid day will tell me I'm making 300 watts from 3000 worth of panels. I have often said that the roof isn't big enough to hold all the panels I'd need to get through the winter. And that is if there was no snow on them. Then in the summer the additional solar would be overkill by a huge margin.

But to this conversation, with four 3.8-48 Phis instead of eight L16 blocks I can go two days without a generator run and still have SOC available. No way with lead. And the charge efficiency of the Phi blocks has saved a lot of gas and generator run time. over the two+ years they have been in service. So in addition to the almost zero maintenance and with the fuel (and running for fuel) savings they are easily saving me $200-300 per year over lead batteries. Oh, BTW, I don't charge them to full and the low voltage alert is set at 25% or 51.5v. The only time the low voltage alert has triggered is when I've tested it 

But I'm not telling y'all anything new.

Dave Angelini

Pretty normal.  The strategy is to shut down strings for summer to protect electronics. In really remote northern locations the "overkill solar" buys piece of mind for winter. They still need a genset,  just alot less hours of it. Hours really drop if the inverter/charger can close loop charge.

 By keeping the array on the ground, it is maintainable with snow and as we age, safety is paramount.

 Winter is what we design for offgrid. The complete opposite of grid tie.

Not sure of the Cascade water/snow catch but the Sierra is way up above me. At almost April, it is remarkable. Alot of water coming down the drainages soon. The Bears are also coming down soon.😉

• Upper Carson Watershed

EBBETTS PASS - SNOTEL 462

March 30, 2023, 1 a.m.

Map ViewRealtime DataSnow ForecastHistorical Data

Geolocation	38.56, -119.80
Elevation	8,765ft.
Last Updated	March 30, 2023, 1 a.m.
Observed Snowpack	193 inches
Percent of Normal	239%
Snow Water Equivalent	39%
Past 24hrs	-2.0 inches
24hr Forecast	0.49 inches
120hr Forecast	5.48 inches
Peak Snowpack	199 inches

JRHill

Fate. Right after I made my last comment about not running the Phis low I am outside hosing mud off the pickup. I neglected to close the hydrant and blew the hose around 11:30pm. The well ran all night until the system shut down around 5:30am. Oops.