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Battery talk (A place to discuss any and all battery technologies where the discussion may not fit into other topic areas) => Lithium => Topic started by: bevans on May 04, 2019, 04:00:16 PM

Title: Let's talk Lithium Ion Chemistries/Physics and Implications
Post by: bevans on May 04, 2019, 04:00:16 PM
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 (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




Title: Re: Let's talk Lithium Ion Chemistries/Physics and Implications
Post by: Matrix on May 04, 2019, 06:03:57 PM
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 (https://www.forbes.com/sites/billroberson/2019/04/23/tesla-looks-into-model-3-fire-caught-on-camera-in-china/#4f23f3067bd9)  just sitting in a parking garage. 
Title: Re: Let's talk Lithium Ion Chemistries/Physics and Implications
Post by: Ron Swanson on May 04, 2019, 06:24:39 PM
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.
Title: Re: Let's talk Lithium Ion Chemistries/Physics and Implications
Post by: bevans on May 04, 2019, 08:18:33 PM
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.

Title: Re: Let's talk Lithium Ion Chemistries/Physics and Implications
Post by: mahendra on May 04, 2019, 09:19:37 PM
Think those chemistries needs BMS and coolant .
Title: Re: Let's talk Lithium Ion Chemistries/Physics and Implications
Post by: ClassicCrazy on May 04, 2019, 09:46:03 PM
You may want to check this book out
https://www.amazon.com/DIY-Lithium-Batteries-Build-Battery/dp/0989906701/ref=sr_1_fkmrnull_1?crid=2UYFYI0MAV64K&keywords=micah+toll+diy+lithium+batteries+how+to+build+your+own+battery+packs&qid=1557020699&s=gateway&sprefix=micah+toll%2Caps%2C532&sr=8-1-fkmrnull

Larry
Title: Re: Let's talk Lithium Ion Chemistries/Physics and Implications
Post by: 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.
Title: Re: Let's talk Lithium Ion Chemistries/Physics and Implications
Post by: ClassicCrazy on May 04, 2019, 10:13:02 PM
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
Title: Re: Let's talk Lithium Ion Chemistries/Physics and Implications
Post by: ClassicCrazy on May 04, 2019, 10:17:37 PM
here is a lithium home brewer
He has lots of videos on all things lithium batteries
https://youtu.be/sjqQZSRlWAA

Larry
Title: Re: Let's talk Lithium Ion Chemistries/Physics and Implications
Post by: Matrix on May 05, 2019, 12:13:12 AM
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
Title: Re: Let's talk Lithium Ion Chemistries/Physics and Implications
Post by: bevans on May 05, 2019, 02:24:35 AM
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)?
Title: Re: Let's talk Lithium Ion Chemistries/Physics and Implications
Post by: Matrix on May 05, 2019, 12:58:56 PM
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
Title: Re: Let's talk Lithium Ion Chemistries/Physics and Implications
Post by: Matrix on May 05, 2019, 01:02:06 PM
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.
Title: Re: Let's talk Lithium Ion Chemistries/Physics and Implications
Post by: bevans on May 05, 2019, 02:18:23 PM
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.
Title: Re: Let's talk Lithium Ion Chemistries/Physics and Implications
Post by: RossW on May 05, 2019, 05:21:22 PM
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...

Title: Re: Let's talk Lithium Ion Chemistries/Physics and Implications
Post by: mike90045 on May 05, 2019, 06:08:33 PM
If you can stand the higher losses, I've been very happy with my NiFe bank (Edison Alkaline Nickel-Iron) and it's fairly bulletproof.   It does live in the battery shed, but only because the battery shed was built before the house.
Title: Re: Let's talk Lithium Ion Chemistries/Physics and Implications
Post by: Ron Swanson on May 05, 2019, 06:37:23 PM
Quote from: RossW on May 05, 2019, 05:21:22 PM
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.

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

This is where I hang up.  We specify industrial FLA banks for 50% DoD.  They last over 10 years like this.  AGM, L16s etc cannot handle this but industrial seem to do fine.

This really tips the cost equation back to FLA.  Time value of money, it is cheaper to pay someone to come look at water levels monthly than to buy Li.

I assume you made a DIY Li battery system though.  In my case I am trying to figure it on cost delivered by a professional to a customer who wants it to work many years with a warranty.  Which means either battery bank needs to have a big manufacturer behind it.

Please post some dollars and cents if you are able.  Last time I looked FLA at 50% vs Li at 100%, Li was still like 3x as costly total cost of job.  I will get some figgers tomorrow.
Title: Re: Let's talk Lithium Ion Chemistries/Physics and Implications
Post by: bevans on May 05, 2019, 08:16:19 PM
Quote from: mike90045 on May 05, 2019, 06:08:33 PM
If you can stand the higher losses, I've been very happy with my NiFe bank (Edison Alkaline Nickel-Iron) and it's fairly bulletproof.   It does live in the battery shed, but only because the battery shed was built before the house.

Mike, what kind of losses are you talking about - what has been your experience with the Iron Edisons? Cost is about the same as lithium, but I am curious. With their storied history and long life it's a surprise they don't hold a bigger share of the market.
Title: Re: Let's talk Lithium Ion Chemistries/Physics and Implications
Post by: bevans on May 06, 2019, 01:03:23 AM
Back to the Volt batteries' LMO-NMC chemistry... If I am able to have custom BMSs made specifically for the Volt batteries and their charging parameters, what glaring challenges remain to achieving a smooth interface with the rest of the system (classics, WBjr, BMK and Magnum 4448pae)? Or is that the main hurdle?

Quote from: RossW on May 05, 2019, 05:21:22 PM
discrete per-cell active balancers (charge-shifting type, not just big fat zener diodes).

RossW, can you explain that difference (charge shifting vs zener diodes)... were these cell balancers a part of the BMS that was factory integrated into your battery bank? What LFPs did you get?
Title: Re: Let's talk Lithium Ion Chemistries/Physics and Implications
Post by: RossW on May 07, 2019, 05:24:00 AM
Quote from: bevans on May 06, 2019, 01:03:23 AM
RossW, can you explain that difference (charge shifting vs zener diodes)... were these cell balancers a part of the BMS that was factory integrated into your battery bank? What LFPs did you get?

The common, inexpensive "balancers" seem to be basically a big, precision zener. When the voltage reaches their setpoint, they start to conduct power. So when the whole string is under charge, as each cell reaches its "full" voltage, the balancer starts shunting current past it to stop the cell overcharging.  The problems with that are that firstly, they won't necessarily shunt the full current past - so if you're charging the bank with more current than the balancer can shunt around the cell, you will still end up over-charging the cell. The second thing is, in off-grid use, you may not get to full charge for an extended period, particularly during marginal weather. And if you're "not full" but "holding on" for days or weeks, charging up to lets say 75%, then discharging down to say 40%, day after day... your cells will never get balanced, and in fact will be getting more and more OUT of balance.

The devices I got have one balancer module per cell and an AC bus between all the balancer modules. They strive, constantly, to keep the cells within a few millivolts of each other. Any cell(s) above average voltage will "donate" power onto the bus, and any cell(s) below the average will "take" power from the bus. This happens when the cells are charging, discharging or just sitting quietly by. It is typically a low current - only a few amps at most - but it's happening ALL the time, so the cells don't get out of balance in the first place. I've never caught mine more than about 12mV difference across an entire pack.

I have one pack of 16 series-connected 300AH prismatic LFP cells, and a second pack of 16 series-connected groups of 3-parallel 200AH prismatic LFP cells. I only charge them to a maximum of 55.5V (3.468V/cell). As soon as the sun goes and the surface charge is knocked down, they settle to 53.0V (3.31V/cell) and after a full night of running all the computers, water pump, lights, TVs, etc, they're usually at 52.4V (3.275V/cell). The generator is set to start if they get below 35% SoC, or down to 48V (3.000V/cell) and the inverter will shut down a little below that. I've had the generator start a few times on SoC, but never on low volts.
Title: Re: Let's talk Lithium Ion Chemistries/Physics and Implications
Post by: tecnodave on May 07, 2019, 12:31:21 PM
Ross,

Please provide link to your cell balancer, I need to read more on this approach......Thanks so much for the high quality information that you provide....
David
Title: Re: Let's talk Lithium Ion Chemistries/Physics and Implications
Post by: mike90045 on May 09, 2019, 12:04:23 AM
Quote from: bevans on May 05, 2019, 08:16:19 PM
Quote from: mike90045 on May 05, 2019, 06:08:33 PM
If you can stand the higher losses, I've been very happy with my NiFe bank (Edison Alkaline Nickel-Iron) and it's fairly bulletproof.   It does live in the battery shed, but only because the battery shed was built before the house.

Mike, what kind of losses are you talking about - what has been your experience with the Iron Edisons? Cost is about the same as lithium, but I am curious. With their storied history and long life it's a surprise they don't hold a bigger share of the market.

A couple % overnight loss
Wide operating voltage range from 50% to Absorb cycle while charging, not all inverters can handle w/out faulting
about 70% recharge efficiency
consumes lots of water
Title: Re: Let's talk Lithium Ion Chemistries/Physics and Implications
Post by: bevans on May 10, 2019, 11:54:43 AM
Quote from: tecnodave on May 07, 2019, 12:31:21 PM
Ross,

Please provide link to your cell balancer, I need to read more on this approach......Thanks so much for the high quality information that you provide....
David

Ross, I second that. Awesome info. Very interested to see what BMS you’re running.This is helping me understand the function and process of a BMS, and give me a healthy respect for how little I know. Do you have further recommendations regarding what to look for in a BMS, or manufacturers/models that have not yet been mentioned in this thread? (Specifically for LG chem cells - lmo-nmc chemistries, if possible)
Title: Re: Let's talk Lithium Ion Chemistries/Physics and Implications
Post by: RossW on May 10, 2019, 08:11:34 PM
Sorry for the slow response - been extra busy with work and other projects!

Firstly, as has been mentioned many times, "BMS" is a confusing term.
Some people interpret it as a "Battery Management System" while others think "Battery Monitoring System".

So I am using 16 discrete cell-balancing modules on each of my two battery banks.
They're similar to these: http://tinyurl.com/y5yhzcyr (http://tinyurl.com/y5yhzcyr) and are available with or without the LEDs.
I have one bank with them, and one without. They perform the same. The LEDs let you see at a glance if any are taking from or donating to the rest. The downside is a small extra current draw.  Not that 16 LEDs is much in the greater scheme of things!

Additional to the balancing system I have a cell MONITORING system. It gives me confidence the BALANCING system is doing its job. There's a rough page describing it at http://support.rossw.net/batterymonitor/ (http://support.rossw.net/batterymonitor/)

The balancers are available in various nominal voltages, they have 2V units for lead-acid, and 3V (or so) for Lithium.
I don't believe there is any significant difference between them except perhaps the current limiting resistors on the LEDs :)

I spent a good while researching them and they appear to be basically a free-running bi-directional inverter. The turns ratio of the transformer is the only critical part. It looks like they'll all synchronise as soon as there's anything on the AC bus, and by virtue of the H-bridge, if the AC side is higher than the DC side (taking turns ratio into account), then power flows into the cell. No smarts, no fancy communications or calibration. Just plain, simple, efficient medium-power stuff with very little to go wrong.

Title: Re: Let's talk Lithium Ion Chemistries/Physics and Implications
Post by: myercreek on December 07, 2019, 08:21:03 PM
After 30 years of using Lead Acid batteries (L16s) for our small home, we took the plunge and replaced the last failing FLAs with 200 amp Lithium Ion batteries from Re-Lion in South Carolina. At my age I had no desire to think about moving 120 pound batteries again in 6 years or so. The new batteries have been in use for 4 months and we are thrilled - no maintenance, no bubbling, no odor - and only 62 pounds each instead of 120 pounds. My only concerns have to do with monitoring the system to know when to use the generator to give them a boost after several days of inversion with little solar gain. (Location is east slopes of the Cascades). Even after several days, the voltage readout goes down to only 12.7 or 12.8 from 13.1, the SOC to 82%. With my FLAs I knew it would take 0.2Kwh gain to raise the SOC 1%. Now the SOC jumps from 87% to 100% with only 0.1 Kwh gain and the V at 12.8 or 12.9. The settings on the Midnite Classic are set such that the generator produces only a float charge to the batteries, yet an hour of generator time bumps the SOC to 100%. My conclusion is to pay more attention to the Volt reading and less to the SOC readings. Suggestions?
Title: Re: Let's talk Lithium Ion Chemistries/Physics and Implications
Post by: boB on December 08, 2019, 03:06:33 AM
Quote from: myercreek on December 07, 2019, 08:21:03 PM
Even after several days, the voltage readout goes down to only 12.7 or 12.8 from 13.1, the SOC to 82%. With my FLAs I knew it would take 0.2Kwh gain to raise the SOC 1%. Now the SOC jumps from 87% to 100% with only 0.1 Kwh gain and the V at 12.8 or 12.9. The settings on the Midnite Classic are set such that the generator produces only a float charge to the batteries, yet an hour of generator time bumps the SOC to 100%. My conclusion is to pay more attention to the Volt reading and less to the SOC readings. Suggestions?

When the Classic goes from Absorb to Float, assuming the Absorb time has been met at or above the Absorb set point voltage, the Classic will reset the SOC to 100%.   That is mainly done for lead acid batteries. 

If Absorb does not terminate to Float, then the amp-hours alone, into the batteries, taking amp-hour efficiency into account, will bring the SOC to 100%.

Is it that the generator is running when the Classic goes from Absorb to Float ?   For lithium batteries, you would most likely have a very short Absorb time, is that correct ?  If so, then the SOC would easily jump to 100% after the Absorb voltage is reached.

Please add to this if you like.




Title: Re: Let's talk Lithium Ion Chemistries/Physics and Implications
Post by: Steve_S on December 08, 2019, 04:55:07 AM
Relion has a Battery Monitor module available for their packs.  It uses a separate shunt for readings.  Here is a YT Video on it:  https://www.youtube.com/watch?v=LUilz14vkzY  it's one option.