My Lithium Upgrade

[rowiebowie]

Here's a general lithium battery life/charge cycle review by Will Prowse.

His claim is that the easiest charge cycle on the batteries is between 75% and 25% SOC (around 5:40 on the video) and not charging them to 100% consistently.

https://www.youtube.com/watch?v=Yf9N9zBgyB8

[booster]

I didn't seem clear if all the graphs were from Battery University or not. It would be interesting to some more information as a lot the claims are very different that what the manufacturers are publishing. In the past, I have not been overly impressed with Battery University stuff, but would need to look at the data to see more.

We have seen some cycle life, or better total energy handled life, charts that showed some similar curves for hot temps and deep discharges, but not really anything solid on the high end. if you start cycling in a range you only use 50% of rated capacity, you are going to spend a lot on batteries for sure, and that also shoots the 50% range the lithium folks always use for AGM comparisons.

I will be going to Battery University to see what they have on there and where the data came from, as that is very important when the claims are this extreme.

I know nothing of the guy making the videos in relation to history or tech ability so can't comment on that. Of course anyone and everyone can be an expert on Utube.

On Edit-did a quick look at Battery University site and it looks like the data and explanations came mainly from there. There are various sources listed, mostly put together by Cadex, it appears. Kind of a hotpudge of lithium battery types and article I saw is nearly 10 years old.

It would be interesting to see what Renogy has to say about those very short life predictions at the specs they are recommending.

If all this is actually true for LiFePo4 batteries, a very large part of their advantage would vaporize quickly, I think. Hard to tell what to think at this point, but if true, the drop in batteries that are claiming you can run 100% discharge and charge to 14.6v should start failing very quickly.

[booster]

With all the discussions of lithium stuff lately including the cold storage recommendations, plus the video that is so different in conclusions than nearly all manufacturers claims, I went to the Renogy site for reminder quick look,


No surprises, except that cold storage temps really seem to be conservative. I can't recall for certain if they were always that way. These are among the most conservatives temps and times we have seen, I think.


https://www.renogy.com/renogy-lithiu...12-volt-100ah/

Can't go below freezing even at 32*F if over 3 months

Can't go below +14*F for 3 months or less (assuming they really meant -10*C

Other of their batteries show different less conservative numbers.



These specs would put a whole lot more of country in trouble for cold storage, I think.

[Winston]

RB, thanks for posting that YouTube link, very interesting - - it begins to answer some of our so-called 'undocumented' rules - - although the video's own authenticity could use additional support/citation.

Taking that video at face value, that first "Battery University" graphic on 1 Year Storage Degradation is startling and not consistent with our experience. And we wish it included a few more values between 40% and 100% SoC. It's hard to say where our batteries 'are' (SoC-wise) most of the time. But we'd guess our batteries average at least 80%. After one year we noticed no degradation. At 2 years, yes, but only a percent or two.

Let's consider his later graphic that suggests charging to 14.1 volts produces an 85-95% SoC and is good. Our measurements establish that the resting voltage of an 85-90% LiFePO2 cell is 3.36 volts corresponding to a pack voltage of 13.44 volts. Of course, if we limit our chargers to 13.44 (or 13.4 as we do), charge times will increase. We can understand taking the charging voltage above 13.4 to hasten the charge - KNOWING that when the charge is removed, the voltage will sag. In short, for those on a tight charging schedule a 14.1 volt charge profile may be good - - but we'd suggest that requires a corresponding 'study' of when an 85-90% SoC is actually reached. We'd point out that the actual SoC achieved by holding a 14.1 volt charge profile will directly depend on time and the actual SoC could range from well below the targeted 85-90% to well over, even 100%. One thing for certain: If you set your chargers to 13.3/4 volts, you'll never exceed a 90% SoC. If you can live with the resulting charge rates, why not operate at this conservative level (which, according to that video may not be conservative - - seems the video advocates cycling around a 50% SoC which, he suggests, might imply taking the SoC to a max of 75%).

A brief comment on our solar controller in view of recent remarks in this thread. As noted, we normally program our Midnite Classic controller to a Constant Voltage of 13.4 volts. Yes, like every other battery related piece of equipment, the MidNite, using its own algorithm, switches between those hated (for us) Bulk, Absorb, and Float modes. We ignore 'the mode' in the knowledge that, eventually, the battery will hit (and rest) at our targeted 13.4 volts. (Indeed, if another of our chargers has caused the voltage to increase above 13.4 volts, the MidNite Classic switches to a fourth mode - - the do nothing mode - - that it calls "Resting".)

So is it time to take another poll - - among lithium users - - what voltage and/or what SoC do you target?

[Davydd]

Originally Posted by booster

With all the discussions of lithium stuff lately including the cold storage recommendations, plus the video that is so different in conclusions than nearly all manufacturers claims, I went to the Renogy site for reminder quick look,


No surprises, except that cold storage temps really seem to be conservative. I can't recall for certain if they were always that way. These are among the most conservatives temps and times we have seen, I think.


https://www.renogy.com/renogy-lithiu...12-volt-100ah/

Can't go below freezing even at 32*F if over 3 months

Can't go below +14*F for 3 months or less (assuming they really meant -10*C

Other of their batteries show different less conservative numbers.



These specs would put a whole lot more of country in trouble for cold storage, I think.

I didn't learn about storage of batteries below -4F (-20C) until after over 1-1/2 years ownership of my lithium batteries when confirmed by Elite Power Solutions, the manufacturer. That was August, 2016. Before that there was a lot of erroneous information being put out and I think it was commonly thought to be about -20F which I believe got confused with -20C. It didn't affect me as I had and still kept my batteries above 41F. But seriously most of the upper United States could go below -4F which freezes lithium batteries and anyone as I said time and time again that buys lithium should have common sense to provide shore power to maintain heat on the batteries or park in a climate conditioned building when not in use and in storage. This is not new. Read this PDF over a year and a half old:

ARV's Lithium-ion White Paper

As far as I am concerned you are beating a dead horse of concern on this cold temperature thing. I have never read on the Internet where RVers have frozen their lithium batteries.

[Davydd]

Originally Posted by rowiebowie

Here's a general lithium battery life/charge cycle review by Will Prowse.

His claim is that the easiest charge cycle on the batteries is between 75% and 25% SOC (around 5:40 on the video) and not charging them to 100% consistently.

He discusses lab results for the first 10 minutes of the video and the last 3 minutes he puts it more in perspective about actual RV use. Pay attention to the last 3 minutes.

It is next to impossible to not top off your batteries 100% when stopping for a night with lithium-ion. And your depth of discharge overnight is not that great. 2000 cycles represent an extreme discharge every day for 5.5 years. Then that is going to get you down to 80% capacity and still functioning lithium-ion batteries. Full timers probably cannot do that let alone us part timers. So, trying to keep an optimum 60% SOC or even 85% SOC is futile and foolish unneeded worry and should be left in the lab.

My batteries are going strong after 5 years with no apparent drop off. Read that ARV Lithium-ion white paper for the reason why.

[avanti]

I honestly cannot understand why it seems so hard to believe that some of us might value the freedom to park without shore power more than we value 800Ah of power. Every time this comes up, people say "every house has an outdoor outlet" or "you can always store your rig indoors". Neither of these statements apply to me. I do not store my vehicle at home. I like where I store it, but it does not have power.

I think lithium is great, and if it had no disadvantages, I would have had it by now. But, the temperature hassles are IMO quite severe, at least for me. I could easily find myself having to fly across the country due to an unexpected cold snap. My 440Ah of battery have proven to give me complete freedom from shore power when I so desire. More amps would just not improve my life. I don't have to experience the joy of never having to plug in--I already have that, and I use my Keuirg and microwave all the time. Others have different situations and different values, which is great.

If no one on the Internet has ever let their battery freeze, that is a statement about lithium battery owners, not about the dangers of freezing, which no one denies.

[rowiebowie]

In my case, the deciding factor on lithiums was space. And specifically, it was the 1/2" narrower width of the Renogy's (they've since come out with a newer and wider 100Ah battery, that would not work for my application). Lithiums were the only way I could add capacity.

Also, size allowed me to relocate the batteries inside. Where I live, and the seasons we travel, low temperatures are not a factor for harming lithium batteries at rest. But there could be one or two Winter mornings I would not want to charge them if I left the van unheated overnight. But that would be attributable to an overabundance of caution since the interior temp is likely to never go below freezing.

[avanti]

Originally Posted by rowiebowie

In my case, the deciding factor on lithiums was space. And specifically, it was the 1/2" narrower width of the Renogy's (they've since come out with a newer and wider 100Ah battery, that would not work for my application). Lithiums were the only way I could add capacity.

Agree. As Davydd mentioned earlier, the unique under-floor storage of the GWV legend made it unusually simple for me to upgrade to a large AGM battery. There is also the obvious weight advantage to Li, which matters to folks on a 2500 platform. There is no doubt that there are big advantages to lithium. Everyone has to decide for themselves whether they outweigh the disadvantages. Denying that the latter exist would be silly.

[booster]

Originally Posted by Davydd

I didn't learn about storage of batteries below -4F (-20C) until after over 1-1/2 years ownership of my lithium batteries when confirmed by Elite Power Solutions, the manufacturer. That was August, 2016. Before that there was a lot of erroneous information being put out and I think it was commonly thought to be about -20F which I believe got confused with -20C. It didn't affect me as I had and still kept my batteries above 41F. But seriously most of the upper United States could go below -4F which freezes lithium batteries and anyone as I said time and time again that buys lithium should have common sense to provide shore power to maintain heat on the batteries or park in a climate conditioned building when not in use and in storage. This is not new. Read this PDF over a year and a half old:

ARV's Lithium-ion White Paper

As far as I am concerned you are beating a dead horse of concern on this cold temperature thing. I have never read on the Internet where RVers have frozen their lithium batteries.

There is no horse here, what I am pointing out that is Renogy seems to have gone to much more conservative temps and times the other suppliers. I have no idea if it is correct or not, or a typo, and never claimed it was. But, the comment about it being a big deal IF TRUE would be important.



The video is also full of information that is very different from other stuff we have seen and talked about. Just like with Renolgy, we have no idea if it is correct or not at this point.


Lithium technology is evolving and davydd says himself that the first he hear about storage temps was well after he bought his ARV. It isn't his fault, or ARV's, it is because the information of the technology has evolved over time as everyone learns.



Hearing all sides, even if very different are good and generate discussion and knowledge accumulation, even if any of us may not agree.

[markopolo]

Originally Posted by rowiebowie

..............
5) A final fact regarding the resting drain. Monitor only shows a drain of 1W (.12A). The SOC has stayed at 83% (166ah) for the entire past week while sitting in the driveway. That is great. ..............

When you have time, would you give us an update on SOC but also include voltage.

[Davydd]

I'm not sure what is evolving in lithium-ion batteries other than just better information is out there but is still misunderstood in a practical way.

[booster]

Originally Posted by Davydd

I'm not sure what is evolving in lithium-ion batteries other than just better information is out there but is still misunderstood in a practical way.

Can't disagree with that statement at all. And all of that may, or may not, apply to video and/or the Remogy spec listed. It is data point in time, not necessarily right or wrong, and how it applies to the real world of RVs is certainly not understood.

[Boxster1971]

Originally Posted by rowiebowie

Here's a general lithium battery life/charge cycle review by Will Prowse.

His claim is that the easiest charge cycle on the batteries is between 75% and 25% SOC (around 5:40 on the video) and not charging them to 100% consistently. . .

That video is interesting. The charts Will presented are reportedly from BatteryUniversity.com - here is link to the source material.

https://batteryuniversity.com/index....ased_batteries

Two charts, attached, struck me as sounding a lot like the 50% rule of thumb for lead-acid batteries to prolong life. I have AGMs now, but will switch to Lithium in my next planned smaller 2500 Sprinter.

My 2019 Chevrolet Bolt EV has ability to adjust the SOC on charging. Chevrolet recommends not fully charging to 100% if you don't need the range. Apple does the same in their software to increase battery life.

As booster mentioned "information of the technology has evolved over time as everyone learns"

[Bud]

"My 2019 Chevrolet Bolt EV has ability to adjust the SOC on charging. Chevrolet recommends not fully charging to 100% if you don't need the range. Apple does the same in their software to increase battery life.

And Tesla controls charging, no 100 or 0 percents. They do reprogram for stuff like hurricanes to allow a greater soc and discharge.

[markopolo]

Those charts are for Lithium-ion cells with a nominal voltage of 3.6V or 3.7V.

They're not the same as LiFePO4 cells with a nominal voltage of 3.2V or 3.3V.

[markopolo]

It appears that the Renogy 100Ah LFP battery is the same as this EWT battery: IFR26650 12.8V 100Ah

EWT 50Ah LFP battery teardown:

https://www.youtube.com/watch?v=xMQUDVZy3nM

I'm more than a bit curious about only seeing 3 red wires. I expected to see 4 in a 4S15P battery. There could be a few explanations for this. You can clearly see one group of 15 paralleled cells. 60 cells in the 50Ah battery.

[markopolo]

Many cells vs few cells - Li-Ion BMS - White Paper - Lots of small cells are better than one big one

[rowiebowie]

Originally Posted by markopolo

When you have time, would you give us an update on SOC but also include voltage.

During the prior 4 day period (below) there was no charging input from any source that I'm aware. Victron solar controller was off, the battery cut-off was in the "Off" position, no power was used, and the van was not plugged in or driven.

I did turn on the monitor "backlight" between the readings below which may account for the higher current draw (which occasionally fluctuates between .01 to .02 amps if you observe it over a 5 -10 minute period), but I never previously noted any difference in draw with the backlight on.


11/20/19 @ 9:00pm - SOC 83%; 166Ah; 13.3 volts; .17A draw


11/16/19 @ 3:00pm - SOC 83%; 166Ah; 13.3 volts; .13A draw


As you can see, the batteries like to rest at 13.3V. This corresponds to what we observed on our first trip.

What I don't understand is why the small .15A average draw, over the 101 hour interval, has not caused a dip in SOC or Amp hours.

EDIT: Don't put too much into the above (except for resting voltage which is what we consistently see). While they are based on two pics taken on my phone, I could have done something in between I don't remember (old timers disease and all), because othwerwise so things don't make sense.

I will officially monitor the batteries (actually log the data on a chart) and give a another report soon. I will include charging observations from various sources.

[rowiebowie]

Originally Posted by Boxster1971

Two charts, attached, struck me as sounding a lot like the 50% rule of thumb for lead-acid batteries to prolong life.

Yeah, I heard that too that lithiums don't have the 50% use restriction of lead-acids. But . . . (isn't there always a but?) they apparently suffer from reduced cycle unless to restricted to less than 100% to 0% charge cycles.

I can't remember who said it, but users will probably use their batteries as needed, and let the charge cycles fall where they may. Less important consideration for lithiums with their additional life cycles.