Battery Cycle question for EG4TechSolutionsTeam

[macdaman]

@EG4TechSolutionsTeam

In an earlier post, you indicated that a battery cycle was One (1) discharge/recharge of 80%. In other words, starting at 100% SOC and discharging down to 20% and then back up to 100% = 1 cycle. Any combination of discharges and recharges that equaled 80% would also count as 1 cycle. Discharging 20% and recharging back to 100% for 5 days would also = 1 cycle.

I have 3 LL-S batteries that have a total storage capacity of 15,360 watts. They've been in service for 77 days and have discharged a total of 651,900 watts or, about 8,466 watts per day. My usage is very consistent from day to day. That works out to an average discharge of 55% each day. This means I should be seeing 1 cycle every 1.5 days (roughly). At 77 days, I should be seeing about 50 cycles on my batteries. Instead, I'm seeing 158 which = 2 cycles per day (almost exactly) or, over three times the expected rate.

I realize you noted in that earlier email that warranty isn't based on cycles but - ALL your marketing materials and spec sheets advertise a "Design Life" of 7000 cycles.

My question is this - will my batteries last 9.5 years at 2 reported cycles a day OR will they last 34.9 years at .55 actual cycles per day? Inquiring minds would love to know (at least mine would).

Noting again a very consistent daily usage. I never discharge below 40% SOC. Most days range from 40% to 90% depending on solar. About once a week, the batteries will charge to 100%.

 

[DougfromdaUP]

Are you gathering this information directly from the batteries using their software? If not, do. And let us know what they say.

 

[macdaman]

Are you gathering this information directly from the batteries using their software? If not, do. And let us know what they say.

EG4 said the Monitor software pulls the info from BMS. They said what I'm seeing is the actual battery cycle count. They also said a firmware upgrade would not be necessary given how new my batteries were.

 

[macdaman]

@SignatureSolarJess

Copying Jess to see if she can get a response

 

[EG4TechSolutionsTeam]

@EG4TechSolutionsTeam

In an earlier post, you indicated that a battery cycle was One (1) discharge/recharge of 80%. In other words, starting at 100% SOC and discharging down to 20% and then back up to 100% = 1 cycle. Any combination of discharges and recharges that equaled 80% would also count as 1 cycle. Discharging 20% and recharging back to 100% for 5 days would also = 1 cycle.

I have 3 LL-S batteries that have a total storage capacity of 15,360 watts. They've been in service for 77 days and have discharged a total of 651,900 watts or, about 8,466 watts per day. My usage is very consistent from day to day. That works out to an average discharge of 55% each day. This means I should be seeing 1 cycle every 1.5 days (roughly). At 77 days, I should be seeing about 50 cycles on my batteries. Instead, I'm seeing 158 which = 2 cycles per day (almost exactly) or, over three times the expected rate.

I realize you noted in that earlier email that warranty isn't based on cycles but - ALL your marketing materials and spec sheets advertise a "Design Life" of 7000 cycles.

My question is this - will my batteries last 9.5 years at 2 reported cycles a day OR will they last 34.9 years at .55 actual cycles per day? Inquiring minds would love to know (at least mine would).

Noting again a very consistent daily usage. I never discharge below 40% SOC. Most days range from 40% to 90% depending on solar. About once a week, the batteries will charge to 100%.

The cycle count of the battery does not directly impact its longevity; however, the State of Health does.

What firmware are the batteries running on?

 

[macdaman]

The cycle count of the battery does not directly impact its longevity; however, the State of Health does.

What firmware are the batteries running on?

I believe in another post, you noted that the firmware could only be determined by taking one of the batteries off closed loop communication with the inverter and running the BMS monitoring software. The batteries were delivered less than three months ago. I would hope their on a very recent version. Is there a way to determine firmware version without disconnecting/connecting and loading another program?

In all the marketing materials for the batteries, it's touted that the batteries should enjoy a 7000 cycle lifetime. How does one read that if cycles mean nothing? I've read a number of posts here that suggests that SOH uses cycles in the equation. For example, SOH = (Cycles x -0.0031)+99.99. If this is true (and what isn't that you read online), that would suggests SOH is somewhat dependent on cycles.

My current SOH on all three batteries is 100% according to the monitor software.

Any idea why I'm seeing 2 cycles a day with only a 55% discharge per day?

 

[Supervstech]

I believe in another post, you noted that the firmware could only be determined by taking one of the batteries off closed loop communication with the inverter and running the BMS monitoring software. The batteries were delivered less than three months ago. I would hope their on a very recent version. Is there a way to determine firmware version without disconnecting/connecting and loading another program?

In all the marketing materials for the batteries, it's touted that the batteries should enjoy a 7000 cycle lifetime. How does one read that if cycles mean nothing? I've read a number of posts here that suggests that SOH uses cycles in the equation. For example, SOH = (Cycles x -0.0031)+99.99. If this is true (and what isn't that you read online), that would suggests SOH is somewhat dependent on cycles.

My current SOH on all three batteries is 100% according to the monitor software.

Any idea why I'm seeing 2 cycles a day with only a 55% discharge per day?

A cycle is a period of discharge to any level, followed by a charge.
Cycle count can be manipulated to show dozens of cycles per day.

 

[macdaman]

A cycle is a period of discharge to any level, followed by a charge.
Cycle count can be manipulated to show dozens of cycles per day.

EG4 has stated before that a cycle was an 80% discharge/recharge. My own experience shows that it is not related to how many discharges there are. My batteries discharge 1 long time per day and recharge 1 shorter time per day. Yet, on average, I see two cycles every day. Further confusing matters, I'll sometimes go a day or two without any cycle increase. My record is 4 cycles in one day. I have three batteries yet the cycle count differs on each one.

Cycles either have meaning or they don't. Find any ad that doesn't tout how many cycles the batteries are rated for. Both EG4 and Signature Solar mention this IN THE FIRST SENTENCE OF THEIR DESCRIPTION (Current Connected drops it to the second sentence). When Will reviews a battery, he almost always mentions this as well as do other YouTube reviewers. This information must be important or it would be embedded near the bottom of a specifications document somewhere. Tell me that someone may look at two different batteries with one touting 6000 cycles while the other 8000 and not get the distinct impression that one is the more robust battery? Yet, once you own one and are seeing those cycles fly by much faster than you expected, it's not important anymore?

At the end of the day, I might alter my processes to make my batteries last as long as possible. I've watched Will's videos and am trying to charge to 100% at least once a week. The problem with 100% every day is the potential loss of solar input when the batteries are full. I don't want to babysit each and every day so have my system reach 90-95% on most days. If it doesn't hit 100%, I'll do a quick charge to force it.

So back to my question above - will my batteries last 9.5 years at 2 reported cycles a day OR will they last 34.9 years at .55 actual cycles per day? Inquiring minds would love to know (at least mine would).

 

[RandyCPU]

EG4 has stated before that a cycle was an 80% discharge/recharge. My own experience shows that it is not related to how many discharges there are. My batteries discharge 1 long time per day and recharge 1 shorter time per day. Yet, on average, I see two cycles every day. Further confusing matters, I'll sometimes go a day or two without any cycle increase. My record is 4 cycles in one day. I have three batteries yet the cycle count differs on each one.

Cycles either have meaning or they don't. Find any ad that doesn't tout how many cycles the batteries are rated for. Both EG4 and Signature Solar mention this IN THE FIRST SENTENCE OF THEIR DESCRIPTION (Current Connected drops it to the second sentence). When Will reviews a battery, he almost always mentions this as well as do other YouTube reviewers. This information must be important or it would be embedded near the bottom of a specifications document somewhere. Tell me that someone may look at two different batteries with one touting 6000 cycles while the other 8000 and not get the distinct impression that one is the more robust battery? Yet, once you own one and are seeing those cycles fly by much faster than you expected, it's not important anymore?

At the end of the day, I might alter my processes to make my batteries last as long as possible. I've watched Will's videos and am trying to charge to 100% at least once a week. The problem with 100% every day is the potential loss of solar input when the batteries are full. I don't want to babysit each and every day so have my system reach 90-95% on most days. If it doesn't hit 100%, I'll do a quick charge to force it.

So back to my question above - will my batteries last 9.5 years at 2 reported cycles a day OR will they last 34.9 years at .55 actual cycles per day? Inquiring minds would love to know (at least mine would).

Could your 3 batteries be charging / discharging at different rates for some reason?

 

[CaliSunHarvester]

I bought batteries and put them in service 8/2024. They are charged daily and discharged at night, typically to 75% (summer) or 60% (winter).

After about 195 days of service, these batteries show a cycle count of 73.

I think the software in the battery (BMS?) handles this calculation OP must have a faulty software.

I don't think that the LFP cells actually suffer from false CC calculations.

My batteries are sold under the SunGoldPower label. I don't know what BMS is in them.

 

[CaliSunHarvester]

back to my question above - will my batteries last 9.5 years at 2 reported cycles a day OR will they last 34.9 years at .55 actual cycles per day? Inquiring minds would love to know (at least mine would).

I think they could last longer than 35 years even, if you keep them at the right temperature.

Remember, in 35years, they are still good. But have only 80%, of original capacity. As you only use 50% of the current capacity, that 20% loss won't be a problem for you.

Biggest issue is the perceived age and value of the problem. Let's say you want to sell those batteries. No buyer will believe this story.

 

[EZPZ]

I also see excessive counts on my lp4 v2 batteries….

 

[macdaman]

I also see excessive counts on my lp4 v2 batteries….

Which brand/model?

 

[Brucey]

There was a firmware bug at least for one battery model where it would count a cycle every time the soc crossed the 90% threshold or something like that.

 

[EG4TechSolutionsTeam]

I believe in another post, you noted that the firmware could only be determined by taking one of the batteries off closed loop communication with the inverter and running the BMS monitoring software. The batteries were delivered less than three months ago. I would hope their on a very recent version. Is there a way to determine firmware version without disconnecting/connecting and loading another program?

In all the marketing materials for the batteries, it's touted that the batteries should enjoy a 7000 cycle lifetime. How does one read that if cycles mean nothing? I've read a number of posts here that suggests that SOH uses cycles in the equation. For example, SOH = (Cycles x -0.0031)+99.99. If this is true (and what isn't that you read online), that would suggests SOH is somewhat dependent on cycles.

My current SOH on all three batteries is 100% according to the monitor software.

Any idea why I'm seeing 2 cycles a day with only a 55% discharge per day?

We believe it is an issue within the firmware on the battery, however our team is working on a firmware to would fix this issue.

 

[rogerheflin]

EG4 has stated before that a cycle was an 80% discharge/recharge. My own experience shows that it is not related to how many discharges there are. My batteries discharge 1 long time per day and recharge 1 shorter time per day. Yet, on average, I see two cycles every day. Further confusing matters, I'll sometimes go a day or two without any cycle increase. My record is 4 cycles in one day. I have three batteries yet the cycle count differs on each one.

Cycles either have meaning or they don't. Find any ad that doesn't tout how many cycles the batteries are rated for. Both EG4 and Signature Solar mention this IN THE FIRST SENTENCE OF THEIR DESCRIPTION (Current Connected drops it to the second sentence). When Will reviews a battery, he almost always mentions this as well as do other YouTube reviewers. This information must be important or it would be embedded near the bottom of a specifications document somewhere. Tell me that someone may look at two different batteries with one touting 6000 cycles while the other 8000 and not get the distinct impression that one is the more robust battery? Yet, once you own one and are seeing those cycles fly by much faster than you expected, it's not important anymore?

At the end of the day, I might alter my processes to make my batteries last as long as possible. I've watched Will's videos and am trying to charge to 100% at least once a week. The problem with 100% every day is the potential loss of solar input when the batteries are full. I don't want to babysit each and every day so have my system reach 90-95% on most days. If it doesn't hit 100%, I'll do a quick charge to force it.

So back to my question above - will my batteries last 9.5 years at 2 reported cycles a day OR will they last 34.9 years at .55 actual cycles per day? Inquiring minds would love to know (at least mine would).

A manufacturer test cycle is typically rated at charging at 1C/.5c and discharging at that same rate or 2x higher.

There is little data on how that compares to a cycle at lower C rates. When I charge aggressively I am around .2C, and discharges are also around .2/.3 C, that is 2.5x lower than the real test uses for charging(.5c), and 3x lower than they used for discharge (1C).

And when looking at 2 difference batteries you need to make sure the test used is the same. Cycle counts have went up on some battery models and others have noticed that charging and/or discharging was reduce by 2x and that seemed to be the reason rather than any design improvement.

And all of this cycle counting (in the BMS) is probably not terribly meaningful and may be terribly misleading, but someone clearly decided to add cycle counts that may or may not be actually measuring anything useful for anything other than telling how long a battery has been in service.

I would suspect that your battery will at most lose(no more than the manufacture predicts) capacity until at least the rated cycle count is hit is in the BMS. But given that no one knows how lower cycles compare (lifetime wise) to the aggressive cycles that the test uses the batteries could last much longer.

In the manufacturers tests the biggest damage is running the batteries hotter (ie run at 40C vs 20C) reduces cycles by a lot, and if the BMS is not fudging cycle count based on battery temperature then it is probably useless.

I would not get overly concerned about the likely arbitrary cycle count any BMS uses as it very well may be absolutely worthless.

 

[macdaman]

We believe it is an issue within the firmware on the battery, however our team is working on a firmware to would fix this issue.

That would be great. Signature Solar told me previously that there was a firmware update for the Lifepower batteries but not the LL-S.

Do we have a timeframe on when it would be released? How would I know when it did?

Thanks!

 

[EZPZ]

Which brand/model?

EG4 lifepower 4 v2

 

[macdaman]

A manufacturer test cycle is typically rated at charging at 1C/.5c and discharging at that same rate or 2x higher.
There is little data on how that compares to a cycle at lower C rates. When I charge aggressively I am around .2C, and discharges are also around .2/.3 C, that is 2.5x lower than the real test uses for charging(.5c), and 3x lower than they used for discharge (1C).
And when looking at 2 difference batteries you need to make sure the test used is the same. Cycle counts have went up on some battery models and others have noticed that charging and/or discharging was reduce by 2x and that seemed to be the reason rather than any design improvement.
And all of this cycle counting (in the BMS) is probably not terribly meaningful and may be terribly misleading, but someone clearly decided to add cycle counts that may or may not be actually measuring anything useful for anything other than telling how long a battery has been in service.
In the manufacturers tests the biggest damage is running the batteries hotter (ie run at 40C vs 20C) reduces cycles by a lot, and if the BMS is not fudging cycle count based on battery temperature then it is probably useless.

I would not get overly concerned about the likely arbitrary cycle count any BMS uses as it very well may be absolutely worthless.

Yea - reading all the threads made my head hurt. It's like interpreting the chalk board in Einstein's lab. My max charge rate is when I have full sun but that's only about 3k per hour into a bank of 15k.

As best I can tell, I'm babying my batteries. They're in a climate controlled space that probably ranges between 60-80 degrees F year round and are butt up against a 10' concrete wall which acts as a heat sync to some extent. At max solar today, my highest cell temp was 25C. I've set my lowest SOC to 40% so as to maintain some capacity during an outage. I try to charge to 100% at least once a week.

As you could probably tell, my biggest "issue" was the fact that cycle counts are yelled from the mountain top as a big thing yet the only way I have to measure them appears to be faulty.

EG4 just replied that they're working on a firmware fix. I'll keep an eye out for that.

Thanks!