Hi All,

So I’ve thinking if I have my batteries connected in a string of 3, doesn’t that make the cycles 15000 cycles if they are 5000 cycles each? Or is this a moot point because they cycle each individually? Sorry for the stupid question just trying to learn more about this. 

Hi @Raiden2912your battery won't be in a string per say. Usually batteries are in parallel assuming these are 24V or 48V batteries. The will cycle 5000 cycles each. When they are paralleled they cycle as one. It will however, take longer for a complete cycle to take place as there is now a large volume of energy. So your thinking is quite accurate in that the cycles take longer but 15000 cycles not really. 

Also another note to add that a lot of ppl are not aware of. The 5000 cycles or cycles count labelled on a lithium battery doesn't mean the battery is dead after the 5000th cycle. The batteries gradually loose capacity over time & most battery manufacturers like FreedomWon & others warranty that there will at least be 60% to 80% in some cases capacity of the original capacity. 

So eg. You have a 10kWh battery. After 5000 cycles that battery is warrantied to have 6kWh capacity. So they battery still has some value & is not ready for the bin. Assuming a cycle a day that is 13 years of service & then they will be still have more than half the original capacity when compared to new. 

 

@Steve87Wow that helps. That you so much it really puts things into perspective. 
 

I have 3x SHOTO SDC-10 box 5 batteries 48v.

@Steve87 I sent Sunsynk an email and logged a call on their website lasy week asking them for the Sun-Batt-5.32 warranty letter that it talks about in the battery brochure as I can find no sign of it on their website and I can't find anything confirming what % life they actually guarantee. 

Most of the suppliers seem to be rather "vague" about what capacity they are actually guaranteeing for 5 years and what is actually classified as a "cycle" i.e. is discharging  the battery to 95% and then recharging it back to 100% classified the same as discharging to 20% and then back to 100%? 

 

Edited July 8, 20232 yr by Sc00bs

That’s another problem most of the batteries manufacturers are VERY vague around what 1 complete cycle is and also my monitoring system Solar Assistant counts cycle for my SHOTO batteries very inconsistently. 

Apples version of a cycle

A charge cycle happens when you use all of the battery's power—but that doesn't necessarily mean in a single charge. For example, you could use half of your laptop's charge in one day, and then recharge it fully. If you did the same thing the next day, it would count as one charge cycle, not two.

That's not solar assistant counting it. That's solar assistant reading what the actual batteries are saying the number of cycles are

Aaahhh ok, thank you 

Edited July 8, 20232 yr by Raiden2912

The most updated Warranty document. They are not vague at all. It's all very well described. 

For SHOTO batteries 

22 hours ago, Raiden2912 said:

That’s another problem most of the batteries manufacturers are VERY vague around what 1 complete cycle is and also my monitoring system Solar Assistant counts cycle for my SHOTO batteries very inconsistently. 

This is due to an incorrect setting in the BMS parameters that counts a cycle every 20% instead of 80%, it's called 'cycle cumulative capacity'.

Thank you @jumper is there a way to fix this? 
so just to clarify if the batteries go down to 80% and back to 100% that’s one cycle? Or every 20% below 100% is 1 cycle? So 

100% to 80% = 1 cycle

80% to 60% = 1 cycle and so on and so forth? Excuse the ignorance 

3 minutes ago, Raiden2912 said:

is there a way to fix this?

You can use the seplos battery monitor software to change the parameter, but it might void your warranty, I did it anyway. Details can be found here: 

 

7 minutes ago, Raiden2912 said:

so just to clarify if the batteries go down to 80% and back to 100% that’s one cycle? Or every 20% below 100% is 1 cycle?

Yes and yes, but it is a bit more detailed as it is cumulative so:

100% down to 80% and back to 100% is counted as 1 cycle.

100% down to 60% and back to 100% is counted as 2 cycles.

100% down to 90% and back to 100% done twice will count as 1 cycle.

Every discharge event in the bms is added up until it reaches 20% (or the value set in cycle cumulative capacity) and then it adds a cycle and starts counting again, it doesn't count the charging at all, only discharge.

Hope that makes it clearer.

So I’ve been incorrectly assuming that 1 cycle is discharging your battery down to 20%, 10% depending on the battery and then when fully charged that becomes 1 cycle…wow now I understand better why people are the way they are (not a negative thing) about batteries preserving.

thank you this has taught me something invaluable today. 

54 minutes ago, Raiden2912 said:

So I’ve been incorrectly assuming that 1 cycle is discharging your battery down to 20%, 10% depending on the battery and then when fully charged that becomes 1 cycle

Your assumption is correct, this is how it should work, but if it counted only when you reach the 20% (or 10%) mark then you could cheat by never going below 30% so it would never count a cycle, so it has to be done cumulatively on discharge for programming purposes. If that parameter is set to the correct value, the cycles are counted correctly.

This is why DOD is usually part of the spec like 6000 cycles @ 90% DOD because if you are not going down to 10% SOC all the time then you should theoretically get more cycles out of the battery, so cumulative is better in that case.

Smart! Thank you 

So one more thing if you cycle your batteries down to 30% daily. That’s 8 hours which theoretically means 8 or 16 cycles. So if SA is reporting a certain number of cycles if you divide that number by 8 or 16 you would get your true cycle number? Is my calculations off here. 

3 hours ago, Raiden2912 said:

So one more thing if you cycle your batteries down to 30% daily. That’s 8 hours which theoretically means 8 or 16 cycles. So if SA is reporting a certain number of cycles if you divide that number by 8 or 16 you would get your true cycle number? Is my calculations off here. 

Somehow I miss something around the 8-16 hours. If the battery is cycled from 100 down to 30% and you do it for 2 days it should come to 1.4 cycles. After doing it 20 days it should be 14 cycles if charged back to 100% daily. 

I stand to be corrected on the above. 

16 hours ago, Raiden2912 said:

So one more thing if you cycle your batteries down to 30% daily. That’s 8 hours which theoretically means 8 or 16 cycles. So if SA is reporting a certain number of cycles if you divide that number by 8 or 16 you would get your true cycle number? Is my calculations off here. 

The easiest way is to just divide by 4 to get the 'real' cycles at 80% DOD as it counts every 20% instead of 80%.

I also use about 30% daily (from 1 battery) and changed my parameter to 90%, so I get 2-3 cycles per week.

This is after almost 1 year of service:

8 minutes ago, jumper said:

The easiest way is to just divide by 4 to get the 'real' cycles at 80% DOD as it counts every 20% instead of 80%.

I also use about 30% daily (from 1 battery) and changed my parameter to 90%, so I get 2-3 cycles per week.

This is after almost 1 year of service:

I stopped worrying about cycle count, also have a battery with a Seplos BMS, as an example see last 30 days dashboard, only once did my battery gone bellow 20% DOD yet it counts one cycle every single day, 

18 minutes ago, Antonio de Sa said:

I stopped worrying about cycle count, also have a battery with a Seplos BMS, as an example see last 30 days dashboard, only once did my battery gone bellow 20% DOD yet it counts one cycle every single day, 

Yeah, cycle count will probably only be an issue in case of warranty claims. I can see down the line, people being told things like "That's normal for a battery with so many cycles to be broken/ not performing / have damaged cells/ less capacity etc. etc.... you'll have to buy a new one." I think it's important for people to know that the cycle count is 4 times higher than it should be... forewarned is forearmed.

Another thing I have read is that the pylontech for example uses the cycle count to calculate and automatically decrease the SOH value and you can see the implications there if it was counting 4x faster. I don't know if the seplos also uses the cycle count for SOH, I've not looked that deeply into it yet.

@jumper, when I got my monitoring system, I realized that it was counting one cycle every single day, even though it was never going bellow 20% DOD. I contacted the battery manufacture namely LBSA, @Bain Viljoen, they did confirm that the battery will count one cycle every time it drops below 80% DOD. However, they have confirmed that the battery has a ten-year guaranty period not based on the number of cycles. The question is? will they still be around in ten years' time? In the beginning I was not very happy with the performance of the battery as one of the cell's never gets to full charge. see dashboard, I have to admit they told me to bring the battery over to the factory and will fixe it however, the battery is now 22 months old, still gets to 99% SOC and still showing 100% health. Now I have to admit, that I made some negative comments about the LBSA battery, but I would like to revert those comments, so far, the battery has been performing to my expectation. Another thing is that I stick to the OEM specifications they guaranty tested at 0,4 C so I charge the battery at 39 Amps and so far, I had some discharge peaks at 40 Amps. 

 

 

Edited July 10, 20232 yr by Antonio de Sa

So, I found an integration for the Seplos BMS's on Guthub and am wondering if anyone knows if it will work with my BSL Batteries, anyone have any idea? 

https://github.com/syssi/esphome-seplos-bms 

 

1 hour ago, Antonio de Sa said:

they did confirm that the battery will count one cycle every time it drops below 80% DOD

My issue is with the vagueness of this statement as well as the fact that it is not quite correct. Did they tell you it would count 2 cycles when it drops below 60% and 3 cycles when it drops below 40%? They should have told you it will count a cycle for every 20% discharged, that would be correct and honest. I guess I'm just a stickler for specifics.

My main issue is that this all stems from one parameter not being set correctly and it doesn't give me much faith in battery "maufacturers" when they just tell people whatever they fell like instead of understanding and fixing the problem.

1 hour ago, Antonio de Sa said:

However, they have confirmed that the battery has a ten-year guaranty period not based on the number of cycles.

At least they have made their guarantee based on age and not cycles, I'll give them that. Does that guarantee that the battery still works after 10 years or that it still has 80% capacity after 10 years regardless of cycles?

 

13 minutes ago, Sc00bs said:

So, I found an integration for the Seplos BMS's on Guthub and am wondering if anyone knows if it will work with my BSL Batteries, anyone have any idea? 

https://github.com/syssi/esphome-seplos-bms 

 

Looks like the BSL might be a Pace BMS, it's not listed with the seplos batteries: https://solar-assistant.io/shop/products/pace_rs232