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Anybody had their packs long enough yet?

Lt.Dan

Solar Wizard
Joined
Dec 25, 2020
Messages
3,528
Location
Tulare, Ca
Hey y'all, has anybody had their packs long enough, or cycled enough times to actually see degradation yet?

I am currently pulling my 2P16S battery apart to make 2x separate 16S Packs inside of Seplos Mason kits, and while I'm waiting on them to show up, I am capacity testing all of the cells, for better grouping. I'm also purchasing more 280ah cells for a 3rd pack. Bringing my total to 1022ah (theoretical and without degradation).

When I did my initial capacity test when I first got the cells, I had them ranging from 262-285ah, not super happy to get some cells under 271ah, but I got them at a decent price, and I didn't want to deal with refunds/replacements etc. When I paired the highest and lowest cells, I averaged out about 274ah each, or 548ah for the pair. Now over the last year is where I really started to pay attention to capacity. And for the last 6 months, I have been cycling from 3.55v to 2.6v once a month or so, to get an update on capacity and overall pack health. Surprisingly I have noticed the pack in the 499ah-500ah range recently. So while pulling them apart I am going to see if they are all degrading evenly, or if I have some outliers that are really bringing the bank down as a whole.

So far I'm on my 3rd cell, and my first one was 250ah, and 2nd was 257ah. Not looking great.

So I set out to see what is expected with the amount of cycles I have put them through. I've also estimated I'm at about 600 cycles, as I have put them through a full cycle every day, for about 2 years. I also have had a couple encounters with a failing Daly BMS about a year ago, that let the cells go below 2v, so this could also be a reason for lost capacity as well. When looking at cycle life charts, I should be somewhere in the 3-5% degradation mark based on my cycle count and DOD, which 5% of 271ah is 257ah! That puts my mind at more ease.

Has anybody else done some math and found similar results? What did you find?
 
Hey y'all, has anybody had their packs long enough, or cycled enough times to actually see degradation yet?

I am currently pulling my 2P16S battery apart to make 2x separate 16S Packs inside of Seplos Mason kits, and while I'm waiting on them to show up, I am capacity testing all of the cells, for better grouping. I'm also purchasing more 280ah cells for a 3rd pack. Bringing my total to 1022ah (theoretical and without degradation).

When I did my initial capacity test when I first got the cells, I had them ranging from 262-285ah, not super happy to get some cells under 271ah, but I got them at a decent price, and I didn't want to deal with refunds/replacements etc. When I paired the highest and lowest cells, I averaged out about 274ah each, or 548ah for the pair. Now over the last year is where I really started to pay attention to capacity. And for the last 6 months, I have been cycling from 3.55v to 2.6v once a month or so, to get an update on capacity and overall pack health. Surprisingly I have noticed the pack in the 499ah-500ah range recently. So while pulling them apart I am going to see if they are all degrading evenly, or if I have some outliers that are really bringing the bank down as a whole.

So far I'm on my 3rd cell, and my first one was 250ah, and 2nd was 257ah. Not looking great.

So I set out to see what is expected with the amount of cycles I have put them through. I've also estimated I'm at about 600 cycles, as I have put them through a full cycle every day, for about 2 years. I also have had a couple encounters with a failing Daly BMS about a year ago, that let the cells go below 2v, so this could also be a reason for lost capacity as well. When looking at cycle life charts, I should be somewhere in the 3-5% degradation mark based on my cycle count and DOD, which 5% of 271ah is 257ah! That puts my mind at more ease.

Has anybody else done some math and found similar results? What did you find?
wow, 600….. haaaa… I just hit 7 total cycles since I started..Gona remain silent…best of luck..?
 
Does NCA Li-ion type count or are you looking for LFP data? I had my Tesla model S modules since 2015 mostly in storage at low SOC and they lost on average 0.7% of capacity per year sitting idle. I just started cycling them in my offgrid setup for past year so I don't have cycling degradation data but so far it does not appear noticeable.
 
Does NCA Li-ion type count or are you looking for LFP data? I had my Tesla model S modules since 2015 mostly in storage at low SOC and they lost on average 0.7% of capacity per year sitting idle. I just started cycling them in my offgrid setup for past year so I don't have cycling degradation data but so far it does not appear noticeable.
Doesn't have to be LFP. Still good info
 
Start using them! They are aging faster than you can use them!
So am I……?….. actually I am using them a good bit but unless the whole bank dips below 50 % discharge , at least on my 712, it doesn’t register a cycle on the phone app.
I am testing doing different things and finding limits and it usually doesnt use half the bank before the sun comes up and takes it back to 100% .
im going to intentionally put some extra loads on it starting tonite and see where it goes.
thx , J.
 
We are about a month or so in to a new lithium installation. Done about 8 cycles according to the app. On a boat using the lithium to cook, heat hot and run the desalination for all our water. All power provided by 720w of solar and a wind turbine. More solar on the way.
Friends is Captain on a superyacht. 10 years old and on its second lithium bank. Lithium bank is in the hot engine room, circa 40degC. Heat does kill lithium. I suspect they will need a third bank soon. I am doing some consultancy on building liquid cooled lithium for high ambient conditions that should extend life by at least 25%
 
We are about a month or so in to a new lithium installation. Done about 8 cycles according to the app. On a boat using the lithium to cook, heat hot and run the desalination for all our water. All power provided by 720w of solar and a wind turbine. More solar on the way.
Friends is Captain on a superyacht. 10 years old and on its second lithium bank. Lithium bank is in the hot engine room, circa 40degC. Heat does kill lithium. I suspect they will need a third bank soon. I am doing some consultancy on building liquid cooled lithium for high ambient conditions that should extend life by at least 25%
You sound young… your lucky… it will all work out for ya…?
 
Hey y'all, has anybody had their packs long enough, or cycled enough times to actually see degradation yet?

A recent post of mine on this forum:

"My 4 cell Sinopoly 300Ah LFP battery has delivered about 5000kWh over the last nine years and counting with a 5% or so capacity loss. 315 down to 301Ah last November.
Number of cycles? Absolutely no idea!

I anticipate a few more years of usable life."

We are fulltime travellers.
The battery also starts our motorhome 3.9l turbo diesel engine often multiple times a day. We have no other battery.

800W solar and c85A charging from the 100A rated alternator. Despite all the doomsayers no smoke yet.
Maximum charge voltage from any source is 14.1V at the battery terminals at which point the battery is always at 100% SOC.
I recently added a 4 cell 280Ah EVE battery in parallel and have yet to hear from the theoretical forum experts to inform us which battery will cause the other to fail prematurely and when. I may be able to answer that question myself in another 9 years from now.
 
Following for more updates! My cells only cycle in the summertime about 2 times per week. I am "hoping" to get ten years out of them. 16s4p 280AH eve cells. So far they don't have capacity loss issues. But its only been about 9 months in operation.
 
So im wondering why some are not using their packs? If you know there is calendar aging, and the battery is slowly dieing anyways, why not use it? Is it just because your overall usage is low and not necessary? If that were the case, why such a large bank? I guess for extended outages or extended sub-optimal PV days. Just thinking out loud here.

I just don't see why you would waste money letting the packs age on their own. Im genuinely curious.
 
So im wondering why some are not using their packs? If you know there is calendar aging, and the battery is slowly dieing anyways, why not use it? Is it just because your overall usage is low and not necessary? If that were the case, why such a large bank? I guess for extended outages or extended sub-optimal PV days. Just thinking out loud here.

I just don't see why you would waste money letting the packs age on their own. Im genuinely curious.
Well I'm not sure on others but I have a very good excuse for not using mine. I haven't bought any yet :)

All pv no batteries on it.

Now my dc stuff doesn't have a counter but it cycles probably every other day with the cloudy/rainy weather we keep having.
 
just wanted to post the info I have on Cycle life as well as calendar aging


Cycle and life of battery vs DoD cycles
battery DoD cycling.jpegbattery DoD cycling 2.jpeg




Calendar Aging
Overview of the factors accelerating the overall calendar aging rate.jpgSummary of calendar aging for all LIB chemistry..jpg




A battery "cycle" is not a predefined measurement, unless it includes the DoD of the "cycle"

With a Solar System, your DoD is going to be very different each day, so its hard to get a good measurement on how many "cycles" your batteries have actually been through.

Because the the complexity of all the factors going into battery health, I find it easier to think of them as a sort of "living" thing when thinking about their health. You can know all of the factors that impact health, but it can be hard to see how all of the factors work together
 
So im wondering why some are not using their packs? If you know there is calendar aging, and the battery is slowly dieing anyways, why not use it? Is it just because your overall usage is low and not necessary? If that were the case, why such a large bank? I guess for extended outages or extended sub-optimal PV days. Just thinking out loud here.

I just don't see why you would waste money letting the packs age on their own. Im genuinely curious.

Probably becuase they are grid tied prepper mindset they have the capacity when its needed, but don't want the fuss of operating them otherwise. They are a backup. (i'd have a generator instead, cheaper and more versatile), then just backfeed full time if the option was there.

For me I use my batteries every night, overnight they use 20% usually of my 1020ah "capacity", they really get a stress test in november-Jan when there is little sunshine! :D, the most I can do in winter without generator or sunshine is 4 days. I have a family of 5 that use the power each day, everyday. But in summer, leave the lights on, run all the AC you want, use every curling iron and blow dryer otherwise the power is wasted anyway! I hooked up my smartload to even AC my garage to keep the new great pyranese pup cool! :D

off grid for the win!

i'm waiting for better, cheaper tech to come out, or the canadian dollar to get better to purchase some server rack batteries. hopefully that's in the next ten years
 
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