Let's talk Lithium Ion Chemistries/Physics and Implications

Started by bevans, May 04, 2019, 04:00:16 PM

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bevans

Hi all,

My name is Ben. I'm new here. Located in SE Arizona and trying to dial in the final steps of my off-grid, diy 48v system install that will power our new little house (which I'm also trying to finish building... electricity would help).

At the crux of my (all?) diy lithium ion storage system is determining and executing best practices for battery balancing and management to ensure safe operation and good bank health. I've quickly observed that the majority of users here have Lithium Iron Phosphate banks, and that many of the BMS's, posts and resources posted are specific to LFPs. So I want to go out on a limb here and ask if we can open a broader conversation about the various Lithium Ion chemistries and consequent similarities and differences in how to balance them in an off-grid, whole house storage application.

The batteries I have in my possession and would like to use are LMO-NMC (Lithium Manganese Oxide (cathode) -Nickel Manganese Cobalt Oxide) from a 2015 Chevy Volt with ~23k miles.What can folks say about this chemistry and their integration within an off grid system? Special considerations for LMO-NMCs? Resources to reference?

The factory BMS pig tails are there, but no BMS, so I'm trying to understand basic concepts like state of health, state of charge, depth of discharge, individual cell voltages, and charge and discharge rates, and how they inform balancing and safe charge controller programming. Am I on the right track here? Where should I be focusing my efforts/research? Dare I ask about the feasibility of safely using this system without a BMS?

Fwiw, here is a fairly succinct comparison of prominent Li Ion chemistries I found helpful early on:
https://batteryuniversity.com/learn/article/types_of_lithium_ion

Big, big thanks in advance. And please tell me if I should relocate this post to the noob section or elsewhere.

bevans




5200w PV array, 16 SunPower 327s
Magnum Energy ms4448PAE inverter/power center
Magnum BMK
Dual Midnite Solar Classic 150s
Midnite WhizBang Jr & shunt
16 kwh Chevy Volt EV lithium ion

Matrix

Are you going to have a separate battery bunker building apart from your house?  I would be concerned putting any Li Chemistry in my dwelling.  I recently watched  video by some "wonder kid" who installed a Tesla Battery in his camper (between his bed and his desk).   Seemed like a really bad idea to me.    Will it catch fire?  Hopefully not.  But Can it?   Here is a recent video of  a Tesla Model S that caught fire  just sitting in a parking garage. 
Grid-Assist Off-Grid
REC TwinPeak 2 285W 3S-3P 2565w-STC 1926w-NMOT Array / Classic 150 / Conext SW 4024 Inverter
Trojan L16H-AC 435Ah bank 4S  with 7' of 4/0 cable
24 volt system /  Need 3200Whs Daily
My System Install

Ron Swanson

I would not put any battery chemistry in the same building as where someone lives.  I know lots of people that do, but they are all low-bid kind of people.  Same for generators.  A power shed is a necessity.

bevans

Thank you Matrix and Ron, yes I completely agree. Safety first.

The power shed is about 40’ from the house. This is a good place to start though... specifically where things could go wrong and possible ways to mitigate? Best practices for safety redundancies with this type of lithium ion?

Ron, I hope no one considers me low-bid, that sounds rather disparaging. I don't imagine I have enough money in the bank to be ranked among the high-bids among us. I'd like to think of myself as an honest asking price people.

5200w PV array, 16 SunPower 327s
Magnum Energy ms4448PAE inverter/power center
Magnum BMK
Dual Midnite Solar Classic 150s
Midnite WhizBang Jr & shunt
16 kwh Chevy Volt EV lithium ion

mahendra

1.5kw on Midnite classic 150(whizbang jr.) networked 0.660kw on classic lite 200 ,180ah CALB Lifepo4 48v battery bank,123SmartBMS bms(top balanced) Outback vfx3648

ClassicCrazy

system 1
Classic 150 , 5s3p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system 2
 5s 135w Kyocero , 3s3p 270w Kyocera  to Classic 150 ,   8s Kyocera 225w to Hawkes Bay Jakiper 48v 15kwh LiFePO4 , Outback VFX 3648 inverter
system 3
KID / Brat portable

Ron Swanson

I would not want to use Li-anything without buying it as a full manufacturer package with built-in BMS and warranty.  Seems too risky otherwise.  Unless you are the rare EE who also knows how to construct things.

They are so expensive, I have not been able to come up with a cost solution that works better even than the most expensive industrial LA.

Somebody prove me wrong, I want to like them but the dollars and cents just don't seem to add up.

ClassicCrazy

Quote from: Ron Swanson on May 04, 2019, 10:07:26 PM
I would not want to use Li-anything without buying it as a full manufacturer package with built-in BMS and warranty.  Seems too risky otherwise.  Unless you are the rare EE who also knows how to construct things.

They are so expensive, I have not been able to come up with a cost solution that works better even than the most expensive industrial LA.

Somebody prove me wrong, I want to like them but the dollars and cents just don't seem to add up.
Some people have done do it yourself power walls using lithium batteries.
But like mentioned above - you would want to put them outside your  home on a brick wall - somewhere that if they go up in flames it won't burn your house down.

You are probably right that there are lead acid technologies that have the performance of lithiums at a lower cost. Probably not at a lower weight though .

Larry
system 1
Classic 150 , 5s3p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system 2
 5s 135w Kyocero , 3s3p 270w Kyocera  to Classic 150 ,   8s Kyocera 225w to Hawkes Bay Jakiper 48v 15kwh LiFePO4 , Outback VFX 3648 inverter
system 3
KID / Brat portable

ClassicCrazy

here is a lithium home brewer
He has lots of videos on all things lithium batteries
https://youtu.be/sjqQZSRlWAA

Larry
system 1
Classic 150 , 5s3p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system 2
 5s 135w Kyocero , 3s3p 270w Kyocera  to Classic 150 ,   8s Kyocera 225w to Hawkes Bay Jakiper 48v 15kwh LiFePO4 , Outback VFX 3648 inverter
system 3
KID / Brat portable

Matrix

Well if we're talkin favorite un protected, none BMS using, used Tesla power wall DIYers... This gent is my hands down fav. Put in his Tesla wall about a year ago, did an update last week.

BTW... I learned everything I learned about what NOT to do for hot water diversion from him too. But he seems to be nice enough.

https://www.youtube.com/user/Hawaiibiz
Grid-Assist Off-Grid
REC TwinPeak 2 285W 3S-3P 2565w-STC 1926w-NMOT Array / Classic 150 / Conext SW 4024 Inverter
Trojan L16H-AC 435Ah bank 4S  with 7' of 4/0 cable
24 volt system /  Need 3200Whs Daily
My System Install

bevans

ClassicCrazy, thanks. I actually have that book on order.

Matrix, you've mentioned Tesla a couple times but Tesla uses Lithium Nickel Cobalt Aluminum Oxide, different chemistry than the LMO Volt batteries. Can you speak to any of the differences or similarities between the two types from first hand experience? Obviously, there are significant risks. I'm trying to understand some of the minutia to determine whether this is within my wheel house, or whether I should abandon the project, which is the message I'm getting from this forum so far. I won't ignore warnings just to hear what I want to hear, but I am also prepared to chew on the nitty gritty details.

Quote from: mahendra on May 04, 2019, 09:19:37 PM
Think those chemistries needs BMS and coolant .

Mahendra, yes the Volt batteries have coolant reservoirs. Do they maintain any function once the bank is out of the car? Is there such a thing as a diy/aftermarket cooling system for LMOs? Other approaches to temp control (passive or active)?
5200w PV array, 16 SunPower 327s
Magnum Energy ms4448PAE inverter/power center
Magnum BMK
Dual Midnite Solar Classic 150s
Midnite WhizBang Jr & shunt
16 kwh Chevy Volt EV lithium ion

Matrix

I'm not smart enough to know if used EV batteries are safe or not. It has been done, and there are plenty of YouTubers  to point it out for you on how to do it .  But For me if I went Li it would only be new LFP with BMS. And for that, the cost still seems prohibited compared to lead acid. I know that led acid has some inherent flaws as well, but given the charge discharge window of lithium the actual usable power is not that much different. With LED acid I can charge safely to 100 % and discharge down to 50%, and sometimes even 45%, with lithium from what I understand you only want to charge to the 93 to 95% window and not discharge down below 20%. So the usable power difference is only about 20%. But the cost of going lfp would be more than double the cost of my current battery Bank
Grid-Assist Off-Grid
REC TwinPeak 2 285W 3S-3P 2565w-STC 1926w-NMOT Array / Classic 150 / Conext SW 4024 Inverter
Trojan L16H-AC 435Ah bank 4S  with 7' of 4/0 cable
24 volt system /  Need 3200Whs Daily
My System Install

Matrix

Just using your link in the original post to battery University, I would be uncomfortable with any chemistry in a stationary mass storage situation that did not rate high on the safety scale. And it appears that mini of the electric vehicle used batteries rate 3 or lower on that one to five scale.
Grid-Assist Off-Grid
REC TwinPeak 2 285W 3S-3P 2565w-STC 1926w-NMOT Array / Classic 150 / Conext SW 4024 Inverter
Trojan L16H-AC 435Ah bank 4S  with 7' of 4/0 cable
24 volt system /  Need 3200Whs Daily
My System Install

bevans

It's a 1-4 scale  ::) but, yes, I'm with you. The cost was a big factor for me... I got 16kwh for around $3k before the price shot up, thinking I could dump what I saved into configuring BMS and monitoring, safety redundancies, etc. like the sharp system mcgivor has setup on NAWS (https://forum.solar-electric.com/discussion/353773/instalation-up-and-running#latest), but with the diy Volt drop-in, it's a hefty task and maybe beyond my risk tolerance.
5200w PV array, 16 SunPower 327s
Magnum Energy ms4448PAE inverter/power center
Magnum BMK
Dual Midnite Solar Classic 150s
Midnite WhizBang Jr & shunt
16 kwh Chevy Volt EV lithium ion

RossW

Quote from: Ron Swanson on May 04, 2019, 10:07:26 PM
Somebody prove me wrong, I want to like them but the dollars and cents just don't seem to add up.

I had FLA and AGM, for several years, and was never happy with either.
Granted, most of the cells were second-hand but (allegedly) in good condition. I had 1500 amp-hours at 48V in three, parallel-connected 500AH strings.

A little over 5 years ago, I ditched the last of my AGM and installed a 300AH bank of LFP, with discrete per-cell active balancers (charge-shifting type, not just big fat zener diodes). The 300AH pack consistently out-performed the remaining 500AH AGM in every metric, indeed it out-performs the previous 1000AH AGM in every regard too.

On cost, when you add up the cost of new lead-acid technology, plus ALL the other stuff - allowing a maximum DoD of 25% or so, the extra power required due to lower cycle efficiency, the per-DAILY-USEABLE-kWh price of LFP is about the same as lead. That is, you cannot sensibly compare the cost of 500AH of LFP to 500AH of AGM, because they are NOT equivalent capacity batteries!

I live in a designated fire-prone area and my home, workshop and offices are one large, burried building. The construction is concrete slab, all walls are concrete besser block, roof is concrete slab. The regulatations, cost and practicality of building an extra battery and/or generator "shed" would have been prohibitive. The generator is in its own room. There are some considerations, the internal door is an explosion/fire rated door and the roof is one of the very few parts of the structure that isn't covered with a concrete slab and 3' of dirt. In the event of a fire or explosion, the roof is the "weak link". The generator room adjoins the battery room which houses the charge controllers, inverters, etc. It is inside the house "shell", but is seperated from the living areas by a concrete wall. Could something go wrong? Of course. But we've taken every practical measure to ensure it can't. Proper fusing, monitoring etc. No other combustible materials nearby. No "smoke and fire path" into living areas etc.

After living with 300AH of LFP for a year, when the opportunity to expand further presented itself, I took it with both hands and no hesitation, and added a further 600AH (taking the total bank to 900AH @ a nominal 53V, for a faceplate capacity of 47.7kWh). With my usage, and the expected cycle life of these cells, I fully expect to get upwards of 20 years of completely maintenance-free, entirely off-grid living from them.

In my mind, LFP (LiFePO4) are one of the safest of the lithium chemistries, don't cost any more than lead-acid (once you factor in their safe cyclical DoD), are 1/4 the size and 1/10 the weight of lead, don't require any maintenance, have cycle efficiencies lead can only dream of (I'm still seeing over 97% CE after 5 years), which means less heat, less wasted fuel on those rare events you DO have to run the generator...

3600W on 6 tracking arrays.
7200W on 2 fixed array.
Midnite Classic 150
Outback Flexmax FM80
16 x LiFePO4 600AH cells
16 x LiFePO4 300AH cells
Selectronics SP-PRO 481 5kW inverter
Fronius 6kW AC coupled inverter
Home-brew 4-cyl propane powered 14kVa genset
2kW wind turbine