LiFePo4 battery users

[tx2sturgis]

Smart phones, most RC devices, and cordless tools use Li Ion.   My main interest is LiFePo4 for house battery duties.   Does your assertion about degradation apply to the LiFePo4 technology?

It's called 'capacity fade', and since larger LiFePo4 batteries for consumer RV/solar are kinda new in the marketplace, there is apparently a shortage of good, long term information.

But I did find this:



Let me know if you find information that indicates otherwise.

[Ticklebelly]

Interesting article and seems to confirm a capacity fade generally consistent with what is put out in manufacturer's data.   Data was collected from about 2012, for about 2 years; latest design batteries incorporate things like Graphine.   Energy density for a 18650 size cell is about right.   Article author has set 80% capacity as his end-of-life point, I wonder how many RV users would even notice that amount of fall off and run out and buy new batteries.   The test bed used seems to be a high end version of of the B6 device I mentioned earlier.

[Ticklebelly]

Just came across an elsewhere forum post that is relevant.   Unpublished results of a capacity test on a 300AH battery bank after 4 years of mobile use in a light truck converted for RV use.   I am not going to copy and post because of IP issues and lack of peer review.   This info is from a person, who enjoys a good technical reputation, who likes Winston batteries and Victron.

Headline info is that after 4 years of use, the capacity of his 300 Ah has been measured at 290 Ah.   Two comments - no capacity test was done at installation so the baseline 300 is what the writing on the battery says is the manufactured capacity.    Second comment, very low charge rate over days brought the batteries to full charge.

My 50 Ah (nominal) cells came with factory final test data that said they were all around the 52/53 Ah capacity leaving the factory.   Using my cells as an example, 300 plated number as a nominal capacity to 290 tested capacity cannot be considered as hard data.

Winston info say 100% charge is to 14.4 at 0.3C.     The batteries tested for the forum report were in use and increased in SOC each day until full charge was reached.   SOC was established by using a watt meter not voltage.   The battery user has decided that for his purposes, 14.2 is the level he considers full charge.   Argue the difference between Winston info and the battery user's ideas if you choose, I'm only telling you what the capacity test used at the top end.   What is interesting to me is that the rested voltage after 10 hours of his fully charged battery was 13.3 Volts.    Rested voltage at the start of testing was 12.5 Volts.   Again interesting to me because I decided on my low end voltage is/will be 11.8 Volts.   I decided on 11.8 because 11.8 is well into the steep downward trend of any discharge curve I can get my hands on but is still some safe level above disaster voltage levels.   Almost ready to bring my low end up a bit but because I rotate my two batteries regularly, neither has reached the low voltage cutoff and I mostly consider the low voltage cutoff as a safety feature, not an operational feature.

One standout comment in the capacity report was that there was a big disconnect between a SOC determined by a watt meter and SOC determined by battery terminal voltage, around the 80% SOC point.   

So a couple of things remain fuzzy for me.   An exact comparison of capacity, at installation to now, has not been done.   Some loss of capacity has been measured but exactly how much is fuzzy.    Manufacturer's data on what final charge voltage level to be obtained is more of a suggestion than an exact rule.   My personal use of 14.1 as a top voltage charge level is close enough for me.   A rested terminal voltage of 13.2 is fuzzy enough for me.   Lastly, any SOC based on voltage is a bit fuzzy, especially around the 80% SOC.   A cheap watt meter around the $30 mark is good enough and is a lot cheaper than a Victron device.    I would like a Victron, just saying that I have other uses for the money, ATM.

[sternwake]

Are some of these lithium batteries in use being a bunch of 18650 cells packed tightly into series parallel configurations while others are 4s Prisimatic Lifepo4 cells?



I'd really enjoy gaining experience with prisimatic Lifepo4. I have a bunch of 18650 cells and used to open up my old laptop battery packs, but these used cells had such poor performance and capacity compared to the panasonic ncr 18650 cells, i quit bothering with them. granted they were low$$ replacement battery packs, hardly ideal candidates for 18650 repurposing.

My main use for 18650s was for head worn flashlights, and my most recent light, an Olight h2r does not need its provided hi rate battery removed for recharging, and if its capacity has declined in the 1.5 years of regular use, I cannot tell.

[tx2sturgis]

Good info TB, and thanks.

I have yet to fully deplete my 100 ah LiFePo4 Battle Born. I have seen the voltage drop to 13.1 and just hang out there for hours with a modest load, then recover to 13.2 when the load is removed. It has been able to recover quickly with a generator/charger combo the next day, multiple times.

It is currently in standby as I slowly get other things done, but I know from experience that all of my drone flight batteries, and my e-bike battery, can contain a lot of energy and seem to hold up well over time. 

I would generally assume that all of these batteries experience capacity fade over time and usage, but the fade is gradual, so its hard to notice in daily use, until you get to the end of life, and it just more or less quits. Electric vehicle lithium batteries tend to do this, as the maximum range of EVs slightly decreases over time and number of charge cycles.

The difference, in my experience, and as I see it, is that lead acid batteries, as they age, take LONGER to charge, and return less on discharge, where the lithium chemistries, as they age, take LESS time to charge and then return less as they discharge.

Is this what you have noticed?

[tx2sturgis]

Are some of these lithium batteries in use being a bunch of 18650 cells packed tightly into series parallel configurations while others are 4s  Prisimatic Lifepo4 cells?

I have not seen large capacity drop-ins using prismatics (or pouch style) for RV use, yet, but maybe they exist.

When you read articles like this, and see the 'swelling' that can occur, believe it!

https://www.epectec.com/batteries/prisma...packs.html

I had an old smartphone do this, while it was on a charger and I was out west.

I'm just really glad that it didnt ignite and burn my place to the ground.

   

   

[TWIH]

I would ask your  question on the Cruisers forum and Wait for Mainesail's response.  Do note you will see John61CT jump in on every thread as an expert as he would do here in his brief stay, or crvl .  Seems a lot of people were calling him out on his zero experience BS there too.  I kind of stopped visiting there much in part to seeing his BS responses on each and every thread, but it has some of the best technical gurus regarding Lifepo4 that I know of on the web.  Basically Mainesail.  That would be the guy I would always seek answers from as his experience and knowledge is unmatched, in my opinion.

http://www.cruisersforum.com/forums/f14/.

Yep, he’s all over any other van, overlander and solar forum I’ve ghosted on.  Maybe all that’s left is NASA and nuclear power plant forums... ?

[Scott7022]

I hesitated to jump into this discussion for a bit as the OP asked about people Actually Using Lithium currently. I, of course, am not as I am travelling/working.

Good info all around and the last bit about Mainesail and cruiser forums is spot on. WHY?

Lead acid on boats sucked. Sucked the most on Sailboats. AGM was better; non-venting and no sloshing. Boat owners have loads of disposable cash. For the most part, they have loads of disposable cash and this is, for the most part, a luxury item. So they were always the early adopters of new tech. Learn using other peoples mistakes. BOAT "Bout Only Another Thousand" Or A hole in the water you toss money.

TechnoMedia did it before most else had heard of it and I watched their trails and tribulations. Since they have gone the give us money for our Data route I no longer follow.

Get the question on the Cruiser forum and wait till Mainesail answers and run with that answer as gospel and you'll have made the best decision, based on the best data available.

I would post it for you but I don't remember my password...

MY lithium Mind lost that 10%

[RoamingKat]

I am a sailor from long ago. A fair amount of what I have done in my rig was because of lessons learned from sailboats.

Very few sailors are actually full time. I know that draining the batteries down to 70% before winter storage was one item on the list to do before lifting out to the cradle. The rest of the time no one actually bothered with them much.

I did follow techno for a while. They abused the first lithium battery they built...shortened the life. But, I (like many) will not be paying anyone to talk to me....so the techno’s and bobs of the world will have to find other rubes.

[Baloo]

After reading this thread, I will stick with lead acid batteries till someone figures this out. I got six years of good use out of my last set.


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