Cycling Degradation Estimation: We are not doing 100% DOD daily

[timselectric]

I agree that temperature is more important than anything else.
Vents are fine in any position, except down. These are not vents that are used for normal operation (like lead acid). They are only used in a failure of the cell.

 

[Will Prowse]

I think only accurate and realistic method to test SOH is a capacity test at a specified rate and temp. What the BMS states is nearly useless.

 

[wiseacre]

speaking of calendar age
I think it's a toss up between me and my batteries

 

[houseofancients]

Temp. Important. I keep mine between 20-25 celsius all year round in my tech room inside.
The trend with hanging batteries outside where there are periods with 40c plus degrees is just stupid. IMO.
Also keep the vents pointing UP.

This

 

[SparkyJJO]

I agree that temperature is more important than anything else.
Vents are fine in any position, except down. These are not vents that are used for normal operation (like lead acid). They are only used in a failure of the cell.

True though my preference is vents up. Based on what data? Um, not much lol. But some cases of blown battery packs where the bottom most cell on the stack made me go ehhhh

 

[Mattb4]

What do you do when the fool battery is still working OK after several years but you really want to replace it with a new higher capacity one? How many cycles or years is it required to keep it?

 

[houseofancients]

What do you do when the fool battery is still working OK after several years but you really want to replace it with a new higher capacity one? How many cycles or years is it required to keep it?

Use it till it dies...

 

[jgh]

What do you do when the fool battery is still working OK after several years but you really want to replace it with a new higher capacity one? How many cycles or years is it required to keep it?

Add the new one in parallel.

 

[jeff.lankford]

speaking of calendar age
I think it's a toss up between me and my batteries

I have to share an unrelated tidbit...

I'm a whitewater kayaker and I only use handmade wooden paddles. There's a local paddle maker nearby in GA who does excellent work. I've had to have some small repairs made over the years and he never charges me for the repair work, even though the damage is clearly from normal use, rock bashing, etc. He gives all his paddles a lifetime warranty. But the joke is that the man is now in his eighties and the warranty is for the duration of *his* lifetime, not the paddle.

 

[Mattb4]

Use it till it dies...

Old LiFePO4 batteries never die. Their capacity just fades away.

 

[BarracudaBob]

I have to share an unrelated tidbit...

I'm a whitewater kayaker and I only use handmade wooden paddles. There's a local paddle maker nearby in GA who does excellent work. I've had to have some small repairs made over the years and he never charges me for the repair work, even though the damage is clearly from normal use, rock bashing, etc. He gives all his paddles a lifetime warranty. But the joke is that the man is now in his eighties and the warranty is for the duration of *his* lifetime, not the paddle.

I had a similar tail of custom fishing rods. A local retired fireman would make me custom rods. As he got older he became more cranky, used less quality eyelets that would rust, and started charging for parts. His memory wasn't as good as it once was and would charge differently then what he quoted. Now I considered him friend so I just looked the other way. I would have received better quality work at a local shop.

I ordered a special rod from him and prepaid. He made something completely different based on his opinion and then couldn't remember that I had paid for it. He took the low road started on rants.

I lost a good friend that day. Different story but relates to ageing. I find my self just not wanting to deal with peoples crap anymore.

It sounds like you had a really good guy there for a long time. Rare these days and their are fewer every day.

People degrade from cycling also

 

[houseofancients]

Old LiFePO4 batteries never die. Their capacity just fades away.

And thus they die a fading death

 

[Danke]

Old LiFePO4 batteries never die. Their capacity just fades away.

 

[wattmatters]

So 0.31% per cycle?

No, 0.0031% per cycle.

 

[HRTKD]

Most of us with PV/LiFePO4 in an RV will see some very long life out of our cells as long as we can keep the temperature in the Goldilocks range. Low temperatures are fairly easy to manage. High temperatures aren't so easy.

 

[fatjay]

There is a DIY UPS thread so I don't want to go too off topic on this one. I want to put a separate UPS system on my Network gear so when I work on my 'big' system that never looses power. Also for alarm, cameras, ect..

Do you just float the LPF?

I didn't do anything fancy, just a power station from temu i got for $500.

https://www.temu.com/2000w-portable-power-station-2073-6wh-lifepo4-battery-power-generator-super-fast-chaging-solar-generator-emergency-power-source-for-camping-power-outage-off-grid-solar-panal-optional-g-601099571091076.html?refer_page_name=goods&refer_page_id=10032_1737267937651_plr7n8jcwp&refer_page_sn=10032&_x_sessn_id=2q477nw4h7

 

[MakeMePower]

The only people who will see cycle limits will probably be robot mower. I own several. they go from 100-25-30% 3 times a day, but they use liion, so 5 years is about the expected limit

 

[BarracudaBob]

The only people who will see cycle limits will probably be robot mower. I own several. they go from 100-25-30% 3 times a day, but they use liion, so 5 years is about the expected limit

That is on my to-do list

 

[PreppenWolf]

In 24 months I had 150 cycles on my 105kWh bank.

 

[BarracudaBob]

Most of us with PV/LiFePO4 in an RV will see some very long life out of our cells as long as we can keep the temperature in the Goldilocks range. Low temperatures are fairly easy to manage. High temperatures aren't so easy.

One of these days i'll be that RV guy. I realized I can't be the Boat Guy and the RV Guy at the same time.

What if the exhaust of the main RV cabin went out where the batteries was. Perhaps it is inertia that blows it out the back but a ventilation of the cabin that goes into the bottom battery tray.

In reality by the time I buy the RV My SOH will probably equal that of the LFP SOH

 

[BarracudaBob]

I think only accurate and realistic method to test SOH is a capacity test at a specified rate and temp. What the BMS states is nearly useless.

I deny the BMS reality and insert my own, Reprogramed.

Done.

 

[macdaman]

I've seen a number of charts similar to this one. If I read it correctly (for whatever battery they're measuring here), you get 3000 cycles of 100% to leave 80% capacity. The 50% life expectancy should be somewhere around 6000 cycles but it shows 7500. This suggests a longer life by not deep cycling.

What am I missing?

 

[Will Prowse]

View attachment 271438
I've seen a number of charts similar to this one. If I read it correctly (for whatever battery they're measuring here), you get 3000 cycles of 100% to leave 80% capacity. The 50% life expectancy should be somewhere around 6000 cycles but it shows 7500. This suggests a longer life by not deep cycling.

What am I missing?

Yes. What's the c rate of this cycle life test? What cell?

 

[Will Prowse]

View attachment 271438
I've seen a number of charts similar to this one. If I read it correctly (for whatever battery they're measuring here), you get 3000 cycles of 100% to leave 80% capacity. The 50% life expectancy should be somewhere around 6000 cycles but it shows 7500. This suggests a longer life by not deep cycling.

What am I missing?

Did you read my post?

 

[macdaman]

Yes. What's the c rate of this cycle life test? What cell?

That I don't know. This was just a representative chart of which I saw a few.